Technical Manual, Seismic Design Guidelines for Upgrading Existing Buildings. · 2012-11-18 · army tm 5-809-10-2 navy navfac p-355.2 air force afm 88-3, chap 13, sec b technical

------

ARMY TM 5-809-10-2NAVY NAVFAC P-355.2

AIR FORCE AFM 88-3, Chap 13, Sec B

TECHNICAL MANUAL

K

SEISMIC DESIGN GUIDELINES FORUPGRADING EXISTING BUILDINGS

DEPARTMENTS OF THE ARMY, THE NAVY, AND THE AIR FORCE1 September 1988

8912140240 891212PDR WASJwM- WAS PDC

REPRODUCTION AUTHORIZATION/RESTRICTIONSThis manual has been prepared by or for the Government and is public property and not subject tocopyright. " tReprints or republications of this manual should include a credit substantially as follows: "Joint Departments of the Army, Navy, and Air Force, USA, Technical Manual TM5-809-10-2/NAVFAC P-355.2AFM 88.3, Chap 13, Sec B, Seismic Design Guidelines forUpgrading Existing Buildings."

, . . .~~~~~~

l

TM 5-809-10-2/NAVFAC P-3SS.2/AFM 88-3, Chap 13, Sec B

TECHNICAL MANUAL HEADQUARTERS DEPARTMENTS OFNo. 5-809-10-2 THE ARMY, THE NAVY, AND THE AIR FORCENAVY MANUAL WASHINGTON, DC, I September 1988NAVFAC P-355.2AR FORCE MANUALNo. 88-3, Chapter 13, Section B

SEISMIC DESIGN GUIDELINES FOR UPGRADING EXISTING BUILDINGSParagraph Page

Chapter 1. GENERAL

Purpose .Scope .Definitions, symbols, and notations.Seismic hazard risk levels............................................................Identification of seismically hazardous buildings.Background .Methodology for seismic evaluation and upgrading existing facilities.References and bibliography .......................................................

Chapter 2. INVENTORY REDUCTIONIntroduction .Availability of building inventory.......................................Building inventory reduction.

Chapter 3. PRELIMINARY SCREENINGIntroduction.Preliminary screening process.Report .

Chapter 4. PRELIMINARY EVALUATIONIntroduction .Preliminary evaluation.............................................................Priorities for upgrading .Report .

Chapter 5. DETAILED STRUCTURAL ANALYSISIntroduction .Acceptance criteria.Methodology for the analysis.........................................................Recommendations. ...................................................................

Chapter 6. DEVELOPMENT OF DESIGN CONCEPTSIntroduction .Acceptance criteria.Development of concepts for seismic upgrading .Strengthening techniques.Upgrading of nonstructural elements. ......................................Concept submittal.

Chapter 7. COST BENEFIT ANALYSIS

Introduction .Earthquake risk .Damageability of the structure .

Annualized repair costs without seismic upgrading.Cost of seismic upgrading .Annualized repair costs after seismic upgrading.Cost versus benefits of a recommended upgrading concept.Report.

Chapter 8. FINAL DESIGN AND PREPARATION OF CONTRACT DOCUMENTS

General .Final design.........................................................................Preparation of project documents.

1-11-21-31-41-51-81-71-8

2-12-22-3

3-13-23-3

4-14-24-34-4

1-11-11-11-11-11-21-31-3

2-12-12-1

3-13-13-2

4-14-24-84-9

5-1 5-15-2 5-15-3 5-15-4 5-3

6-1

6-26-36-46-56-6

6-1

6-26-26-96-376-37

7-1 7-17-2 7-17-3 7-27-4 7-37-5 7-37-6 7-37-7 7-47-8 7-7

8-1 8-18-2 8-18-3 6-1

I

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sc BParagraph Page

Chapter 9. SEISMIC UPGRADING OF NONSTRUCTURAL ELEMENTSIntroduction .......................... i........................................... 9-1 9-1Acceptance criteria .9-2 9-1General considerations ................................................ ........... 9-3 9-1Qualitative evaluation. 9-4 9-1Detailed evaluation.................................................................. 9-5 9-2Representative upgrading techniques .9- 9-2

Appendix A. SYMBOLS AND NOTATIONS .. A-1Appendix B. REFERENCES .. B-1Appendix C. STATIC CODE PROCEDURE .. C-1Appendix D. SUMMARY OF THE RAPID SEISMIC ANALYSIS PROCEDURE . .D-1Appendix E. GUIDELINES FOR THE EVALUATION OF EXISTING MATERIALS. ............................ E-1Appendix F. DESIGN EXAMPLES-STRUCTURES .. F-1Appendix G. DESIGN EXAMPLES-NONSTRUCTURAL.. G-1Bibliography ....... Bibliography 1Index ....... Index

Fzgure No. LIST OF FIGURES Page1-1. Methodology for seismic evaluation and upgrading....................................................... 1-42-1. Methodology for inventory reduction .2-23-1. Methodology for preliminary screening................................................................... 3-14-1. Methodology for preliminary evaluation.................................................................. 4-14-2. Force-displacement capacity curve .4-34-3. Capacity spectrum curves. 4-4-4. Tripartite plot of response spectra shown in SDG figure 2-8 .4-74-5. Response spectrum plotted in terms of Sd vs T and S. vs Sd .4-8

4-6. Capacity spectrum method for preliminary evaluation....................................... 4-105-1. Methodology for detailed structural analysis of buildings....................................... 5-26-1. Methodology for development of design concepts for seismic upgrading .6-16-2. Strengthening of existing columns .6-216-3. Strengthening of existing beams......................................................................... 6-2264. Strengthening of existing bracing........................................................................ 6-236-5. Modification of an existing simple beam connection to a moment connection .6-246-. Modification of existing steel framing for diaphragm chord forces .6-256-7. Strengthening of existing reinforced concrete or masonry walls or piers .6-266-8. Strengthening of existing connecting beams in reinforced concrete or masonry walls .6-278-9. Strengthening of existing reinforced concrete or masonry walls by filling in of openings..................... 6-288-10. Strengthening of existing unreinforced masonry walls or piers. ...................................... 296-11. Bracing of heavy timber construction .6-306-12. Knee bracing of heavy timber construction .6-S316-13. Strengthening existing wood stud walls with let-in bra0ing.6-326-14. Strengthening of existing wood disphragms in reinforced masonry buildings .6-36-iS. Strengthening of existing wood diaphragms in teel fram buildings .. 6416. Superimposed diaphragm slab at an existing masonry wall.6 .3

6-17. Diaphragm chord for existing concrete slab .6-356-18. Strengthening of openings in a superimposed diaphragm .6-366-19. Strengthening of existing steel deck diaphragms......................................................... 6-366-20. Underpinning of an existing footing..................................................................... 386-21. Upgrading of an existing pile foundation .6-406-22. Removal and replacement of an unreinforced masonry wall .6-416-23. Upgrading an existing building with external frames . 6-426-24. Strengthening of an existing concrete frame building with a reinforced concrete shear wall .6-446-25. Steel shear wall in an existing building.................................................................. 6-466-26. Strengthening of an existing building with eccentric bracing. 6-476-27. Strengthening of an existing steel frame building with horizontal bracing .6-486-28. Braced structural steel buttresses to strengthen an existing reinforced concrete building ...... ............... 6-507-1. Acceleration response spectra normalized to Og. . 7-2

II

TM 5-809-10-2/NAVFAC P-35S.2/AFM 88-3, Chop 13 Sec B

FOREWARDThis manual on seismic upgrade design guidance for existing buildings was developed as a sequel to themanual for new construction, TM 5-809-1/NAVFAC P-355.1/AFM 88-3, Chap 13, Sec. A Seismic DesignGuidelines for Essential Buildings. This manual meets one of the objectives of the EARTHQUAKEHAZARDS REDUCTION ACT of 1977 (Publication 95-124), i.e., to provide improved seismic design andconstruction requirements to upgrade existing buildings in seismic areas.

This manual provides the seismic design upgrade concepts for existing buildings based on thestate-of-the-art methodology and past practices by the triservices (Army, Navy and Air Force) and theprivate sector. It includes the dynamic-analysis approach similar to new construction concepts with somemodifications/tolerances on the acceptance criteria. A methodology for screening, evaluating and prioritiz-ing seismically hazardous buildings from a large number of buildings in a military installation and theNavy's Rapid Seismic Analysis Procedure are provided. For existing buildings in seismic zones 1 and 2, astatic code procedure is provided to evaluate and upgrade resistance to collapse in the event of a majorearthquake, as required by the code provision.

The general direction and development of this manual were under the supervision and guidance of theOffice of the Chief of Engineers, Headquarters, Department of the Army, Washington, D.C. Assistance wasprovided by the Headquarters, Naval Facilities Engineering Command, Department of the Navy,Washington, D.C. and the Directorate of Engineering and Services, Headquarters, Department of the AirForce, Washington, D.C.

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec BFigure No. LIST OF FIGURES Page

C-1. Methodology for static code procedure .C-2D-1. Site response spectra for a Naval activity in southern California .D-3D-2. Graphical illustration of damage estimation .D-6D-3. Example of steel building .D-12D-4. Example of concrete building ............................................................................ D-19F-i. Sample screening and evaluation of a large military installation ........................................... F-2F-2. Brick building with concrete framing system ................. ............................................ F-14F-3. Building with steel ductile moment-resisting frames and steel braced frames ............................... F-39F-4. Building with concrete moment-resisting frames and shear walls .......................................... F-62G-1. Nonstructural partition ............................................................................... G-2G-2. Unit heater . ............................................................................... G-5G-3. Light fixtures . ............................................................................... G-7G4. Tank system bolted to floor of building ................................................................... G-8G-5. Piping system ..................................................................................... G-9

Table No. LIST OF TABLES Page4-1. Calculation of Stand Sd capacity values ................... ............................................... 4-54-2. Damping values of structural systems .................................................................... 4-95-1. Inelastic demand ratios for existing buildings ............................................................. 5-46-1. Strengthening options for unreinforced concrete or masonry buildings ...................................... 6-86-2. Strengthening options for reinforced concrete or masonry shear wall buildings .............................. 6-106-3. Strengthening options for reinforced concrete frame buildings ............................................. 6-126-4. Strengthening options for steel moment-resisting frame buildings ......................................... 6-136-5. Strengthening options for steel braced frame buildings ............ ........................................ 6-166-6. Strengthening options for heavy timber frame buildings ................................................... 6-186-7. Strengthening options for wood stud framed buildings ..................................................... 6-196-8. Strengthening options for steel stud framed buildings ..................................................... 6-207-1. Probabilities of exceedance of peak ground acceleration in 50 years, NAS Moffett Field, California ........... 7-17-2. Summary of a cost benefit study for an existing building without seismic upgrading ...... .................. 7-57-3. Summary of a cost benefit study of an existing building with seismic upgrading ............................ 7-69-1. Guidelines for evaluating seismic performance of selected nonstructural elements ........................... 9-3D-1. Major steps of the Rapid Seismic Analysis Procedure (RSAP) .............................................. D-2D-2. Damping values ........................................................................................ D-2D-3. Ductility factors ................................................................................... D-4D-4. Sample output of damage estimate for a steel building from computer program CEL 9 ...... ................ D-8D-5. Response spectra for steel building, example ............................................................ D-9D-6. Output for steel building, example 1 ..................................................................... D-10D-7. Output for concrete building, example 2 .................................................................. D-1

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

CHAPTER 1

GENERAL

1-1. PurposeThis manual prescribes criteria and furnishes de-sign guidelines, procedures, and strategy to screen,prioritize, evaluate, upgrade, and strengthen exist-ing facilities for seismic resistance. These criteriaapply to all elements responsible for the design ofmilitary construction in the high seismic regionsand will apply to all existing facilities in SeismicZones 3 and 4, to only existing essential facilitiesin Seismic Zone 2, and to other facilities desig-nated by the approving agency. These guidelinesalso provide procedures and guidance for engineersto identify seismically hazardous buildings and todetermine the strengthening method to resist therequired seismic forces. This manual is a supple-ment to TM 5-809-10/NAVFAC P-355/AFM 88-3,Chapter 13, referred to herein as the Basic DesignManual (BDM) and TM 5-809-10-1/NAVFACP-355.1/AFM 88-3, Chapter 13, Section A, re-ferred to herein as the Seismic Design Guidelines(SDG).

1-2. ScopeThese guidelines encompass a strategy and methodto identify potential seismically hazardous build-ings on a priority basis. The guidelines include astep-by-step procedure involving building inven-tory reduction; preliminary screening; preliminaryevaluation; detailed structural analysis; develop-ment of design concepts for seismic upgrading/strengthening; cost benefit analysis; final designand preparation of contract documents; and seis-mic upgrading/strengthening of nonstructural ele-ments. The problems relating to earthquake-induced ground failures and tsunami are stated inthe BDM, paragraph 2-7, and will not be coveredin this manual. Authorization from HQDA(DAEN-ECE-D) WASH, DC 20314-1000, NAVFAC Code4BA 200 Stovall Street Alexandria, VA 22332, orHQ USAF/LEEE WASH, DC 20332 is required forthe application of the procedures in this manual.

1-3. Definitions, symbols, and nota-tions

Unless otherwise noted in this manual, all defini-tions, symbols, and notations will be as indicatedin chapter 3 of the BDM. Symbols and notationsare listed in appendix A.

1-4. Seismic hazard risk levelsThe evaluation and upgrading of existing build-

ings is based on seismic ground motions of tworisk levels as specified in chapter 3 of the SDG.

a. The selected risk levels of the two designearthquakes, EQ-I and EQ-fI, are based on De-partment of Defense standards; however, the risklevels may be revised as warranted by approvalauthorities.

b. As an alternate, the code provisions providedin appendix C may be used for high risk ornonessential buildings in high seismic regions aswarranted or deemed appropriate by approval au-thorities.

1-5. Identification of seismically haz-ardous buildings

The military has a large inventory of buildings,and an effective strategy method is required toidentify potentially hazardous buildings on a prior-ity basis. The objective of this strategy/method isto minimize unnecessary investigations by elimi-nating buildings of minor importance and lowhazard exposure from the large inventory, identify-ing groups of similar buildings, and prioritizingseismic safety evaluation and hazard mitigation(strengthening) efforts. Since the basic goals ofseismic hazard mitigation for existing buildingsare to enhance life safety (i.e., protection againstcollapse) and post-earthquake operational capabil-ity, it is essential to identify buildings with post-earthquake operational requirements or high risk(high-loss potential) functions.

a. The essential buildings with post-earthquakeoperational requirements are:

(1) Hospitals(2) Fire stations, rescue stations, and struc-

tures housing vehicles essential for post-earthquake rescue and relief operations.

(3) Power stations and other utilities requiredas emergency facilities.

(4) Mission essential facilities. The decision todesignate a building as "mission essential" is theresponsibility of the operating Command. Since itmay be possible to pick up the function of anentire Base at other locations, the decision todesignate a structure as mission essential shouldbe confirmed at the major command level orhigher.

(5) Primary communications or data-handlingfacilities. (Some of these may be mission essential,but this category is not limited to missionessential.)

1-1

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

(5) Primary communications or data-handlingfacilities. (Some of these may be mission essential,but this category is not limited to mission essen-tial.)

(6) Facilities involved in operational missilecontrol, launch, tracking, or other critical defensecapabilities.

(7) Facilities involved in handling, processing,or storing sensitive munitions, nuclear weaponry,gas and petroleum fuels, and chemical or biologi-cal contaminants.

b. High-risk (high-loss-potential) buildings arethose whose primary occupancy is for assembling alarge number of people, or where services areprovided to a large area having many other build-ings. Buildings in this category may suffer damagein an earthquake, but are recognized as warrant-ing a higher level of safety than an ordinarybuilding. Typical examples are:

(1) Buildings whose primary occupancy is thatof an auditorium, recreation facility, dining hall,or commissary, any of which may have an occu-pancy of more than 300 persons.

(2) Confinement facilities.(3) Central utility facilities (power, heat, wa-

ter, sewage) that are not required as emergencyfacilities and that serve large areas.

(4) Buildings housing valuable equipmentwhose justification ii provided by the usingagency.

c. All other buildings are considered nonessen-tial, ordinary buildings of lesser importance whichwill require the life safety provision, i.e., againstcollapse, unless a higher upgrade is warranted byapproving authorities.

d. Hazardous critical facilities (e.g., nuclearpower plants, dams, and LNG facilities) are notincluded within the scope of this manual, but arecovered by other publications or regulatory agen-cies. For any facilities housing hazardous itemsnot covered by criteria, advice should be soughtfrom DAEN-ECE-D (Army), NAVFAC Code 04BA(Navy), or HQ USAF/LEEE (Air Force).

1-6. BackgroundaC Seismic design criteria In recent years, devel-

opments in earthquake engineering have resultedin substantial changes in seismic design criteria.In the 1960's, major changes began to occur in theseismic design codes. In 1966, the first edition ofthe "Seismic Design for Buildings" was introduced(TM 5-809-10/NAVDOCKS P-355/AFM 88-3,Chapter 13, March 1966). In 1973, a new revisedand expanded edition of the manual was published(TM 5-809-10/NAVFAC P-355/AFM 88-3, Chap-ter 13, April, 1973) which included ductility provi-

sions for moment resisting space frames. In theFebruary, 1982 edition (i.e., the BDM) substantialchanges were made in force levels and seismicdetailing requirements. Many of these changeswere in response to experiences from the 1971 SanFernando, California earthquake. In the late1970's, areas in the United States outside ofCalifornia and the Pacific Coast area began to beaware of the need for earthquake-resistant designrequirements for their facilities. In 1978, "Ten-tative Provisions for the Development of SeismicRegulations for Buildings" was published by theNational Bureau of Standards (NBS SP-510; Ap-plied Technology Council, ATC 3-06; and NationalScience Foundation, 78-8). These provisions weredeveloped through a nationwide effort to improveseismic design and construction building practicesand are currently being evaluated by a nationalcommittee. In addition to the static force approachused in codes and manuals, there was a need for adynamic analysis approach to seismic design foressential buildings. In 1986, the Tri-Services pub-lished the SDG to provide guidelines for the designof essential buildings, as well as other structures,by means of a two-level dynamic analysis proce-dure.

b. Existing buildings. Major changes in struc-tural criteria based upon building failures in pastearthquakes naturally raise the question of theadequacy of existing buildings. A building de-signed and constructed prior to the recent changesin seismic design criteria, especially those in highseismic areas, will probably not conform to therequirements of today's criteria. In some cases, thegeneral structural system does not conform, andthere are some cases where the new lateral forcelevels can be 3 or more times greater than forcesused in the original design. This does not necessar-ily mean that all these buildings are unsafe or willnot be able to perform adequately when subjectedto a major or moderate earthquake. Some of theolder buildings may actually perform better thannew ones that conform to the latest provisions.Many of the performance capabilities of buildingsdepend on configuration, details, and ability to actin a tough, ductile, energy absorbing mannerrather than on conformance to the minimumstandards of the code provisions.

c. Evaluation and upgrading. Current codes aredeveloped for new construction and are not neces-sarily applicable to existing buildings. An existingbuilding should be evaluated on the basis of itsactual performance characteristics, as best as theycan be determined, when subjected to a realisticpostulated earthquake. Modifications of existingbuildings shall take into account the performancecharacteristics of the existing materials interact-

1-2


ing with the new materials used to upgrade thestructure.

1-7 Methodology for seismic evalua-tion and upgrading existing facil-ities

The various steps in the methodology which areoutlined below and graphically in figure 1-1, arepresented in detail in the following chapters ofthis-manual. It should be noted that the methodol-ogy as shown is applicable to a military installa-tion with a large inventory of buildings. Theapproval authority may direct the omission of oneor more steps in the methodology. For example, foran installation with a limited number of buildings(e.g., 25 or less) that are in use, the inventoryreduction may not be required. If only essentialbuildings at a given facility are to be consideredfor seismic upgrading, the inventory reduction,preliminary screening, and preliminary evaluationmay be omitted and the upgrading evaluationwould directly begin with the detailed structuralanalysis, with or without the cost/benefit analyses.

a. Inventory reduction (chapter 2). Prior to begin-ning the phased seismic evaluation procedure, theoverall inventory of the installation is reviewed toselect buildings that will be included in the evalu-ation program. The purpose of reducing the totalinventory to a select group is to eliminate unneces-sary investigations and to keep the scope of workwithin reasonable limits.

b. Preliminary screening (chapter 3). A site sur-vey is made to visually inspect all the buildings onthe select inventory list. A screening process isused to reduce the number of buildings thatrequire the preliminary evaluation.

c. Preliminary evaluation (chapter 4). A struc-tural analysis of each selected building from thepreliminary screening is made using simplifiedtechniques. The purpose of the evaluation is toestimate the vulnerability of the buildings (i.e.,damage when subjected to site specific seismicground motion) and to establish a priority listingfor more detailed structural analysis.

d. Detailed structural analysis (chapter ). Build-ings are selected for the detailed analysis on thebasis of the priority listing resulting from thepreliminary evaluation or by direct request by theauthorized agency. The purpose of the detailed

structural analysis is to determine if the existingbuilding will satisfy the acceptance criteria, toidentify deficiencies, and, if required, to recom-mend alternatives for seismic upgrading.

e. Development of design concepts for seismicupgrading (chapter 6). On the basis of the detailedstructural analysis, methods of seismic strengthen-ing are studied. A general concept is developed asrecommended in the detailed structural analysisfor seismic upgrading. In some cases, an alternateconcept may be included.

f Cost-benefit analysis (chapter 7). The costs ofseismic upgrading are compared to the risk ofdoing nothing and to the costs of a new building.An evaluation may also be made for various levelsof rehabilitation in comparison to the risk offuture damage. The results of the cost-benefitanalysis will be used for setting priorities inrelation to other buildings.

g. Final design and preparation of contract docu-ments (chapter 8). The proposed upgrading conceptswill be used as a basis for the development of thefinal design for seismic upgrading. The final de-sign will include a complete analysis of the modi-fied building to confirm the adequacy of thestrengthening measures in accordance with thedetailed structural analysis procedure. Contractdocuments will include drawings and specifica-tions.

h. Nonstructural elements (chapter 9). A qualita-tive evaluation is made on the basis of availabledocuments and an on-site inspection. Elementsidentified as being susceptible to damage aresubjected to a detailed analytical evaluation by astatic or dynamic approach. Recommendations forseismic upgrading are made if required.

i Evaluation of existing structural materials (ap-pendix E). Where necessary data or information ofthe existing materials are not available, the mate-rials and structural elements will be tested. Test-ing procedures and methods for materials andstructural elements are provided.

1-8. References and bibliographyPublications that are referenced in the text andare required reading for use of this manual arelisted in appendix B. Publications for suggestedreading are listed in the bibliography.

1-3

TM 5-809-102INAVFAC P-355.2/AFM 88-3, Chop 13, Sc B

FPgure 1-1. Methodology for scimic evaluation and upgrading

1-4

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sc B

CHAPTER 2

INVENTORY REDUCTION

2-1. Introduction.Generally military installations have a large in-ventory of existing buildings and the potentialhigh cost of an engineering investigation of all ofthe buildings located in high seismicity areasmakes it necessary to identify seismically hazard-ous buildings in a carefully planned manner. Thefirst step in dealing with a large inventory ofexisting buildings is to apply some type of screen-ing process to reduce the inventory and to elimi-nate unnecessary investigation. Certain categoriesof existing buildings represent an acceptable levelof risk. Criteria for reducing the number of build-ings in the inventory to be investigated are givenbelow. However, this does not preclude the investi-gation of any of these buildings if the responsibleagency directs that they remain in the inventoryto be investigated.

2-2. Availability of building inven-tory.

The military maintains a central inventory of realproperty which is the basic source of informationon the status, cost, capacity, condition, use, main-tenance, and management of its installations. Inaddition to specific information regarding the in-stallation, the real property inventory contains adetailed record for buildings and facilities, includ-ing information such as type of construction, build-ing/facility number, total area, total capacity, totalacquisition cost, year built or acquired, and num-ber of floors.

2-3. Building inventory reduction.

To expedite identification of the more importantbuildings in the military real property inventory,a procedure was developed to screen the inventoryfor a given installation or group of installations ina particular high seismicity region. The screeningprocedure, which is graphically outlined in figure2-1, utilizes the following criteria for the exclusionof buildings to reduce the inventory. An exampleis given in appendix F, figure F-1, sheet 1 of 12.

a Buildings, except essential buildings, thatwere designed in accordance with the provisions ofthe 1982 Basic Design Manual (BDM) or equal(e.g., 1976 Uniform Building Code (UBC), or tomore stringent requirements).

b. Buildings located in seismic zone 0.c. One-story wood-frame and one-story preengi-

neered metal buildings, except essential or highrisk buildings.

d. Buildings occupied by no more than 5 occu-pants, except essential or high-risk buildings.

e. One- and two-family housing, two stories orless.

f Buildings, except essential or high-riskbuildings, of no more than 500 square ft or with areplacement cost of less than $50,000.

g. Structures scheduled for replacementwithin 5 years.

h. Modifications and additions to the abovefactors authorized by the approval agency.

2-1

TM 5-809-102INAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

LAPPrOVAl

I

r Prel-lnnry screening - I

L (Chapter 3) __ I

Figur 2-1. Methodology for nventory reduction

2-2


CHAPTER 3

PRELIMINARY SCREENING

3-1. IntroductionThis chapter describes the general procedures forthe preliminary screening of existing buildings.Guidelines are presented for the preliminaryscreening process to classify and categorize thebuildings and criteria are provided for screening ofbuildings from further consideration.

3-2 Preliminary screening processPreliminary screening will be used after inventoryreduction only if there is a need to further reducethe number of structures to be evaluated. A flowchart is shown in figure 3-1.

a. Classification. The buildings remaining afterthe inventory reduction will be classified as essen-

I Buildings frm II inventory eduction II (Chapter 2) 1L- ___ ___

, Preliminary evaluationII (Chapter 4) -

.~~ ~ ~ _-

Figure 3-1. Methodology for preliminary screening

3-1

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sac B

tial, high-risk, or all others in accordance withparagraph 1-5. Classification of the buildings willbe provided by the using agency or will be per-formed by the engineer in collaboration with theusing agency. The function of the building will benoted by the engineer during the site visit for thepreliminary screening and any apparent discrep-ancy in the classification will be resolved with theusing agency.

b. Available design data. The engineer will ob-tain available design data (e.g., drawings, designcriteria, calculations, and specifications). Data per-taining to the "as-built" condition of a buildingare essential when available. The engineer willnotify the using agency so that the assembly ofselected available building data can be transferredto the engineer prior to the site visit. These dataand information will be reviewed by the engineerand the pertinent information will be transferred-to the screening form used in the review process.It is expedient to transfer as much data as possibleto the forms. An example is shown in appendix F,figure F-1, sheet 4. When the design data areminimal or if none is available, such as may be forthe older buildings, it will be noted on the screen-ing form so that sketches with pertinent dimen-sions, sizes, and other notes regarding the struc-tural systems can be made during the preliminaryscreening inspection. Older buildings are morelikely to have undergone structural revisions andadditions. Indications of such revisions and addi-tions will be noted and confirmed. Data mayrequire revision during the field inspection.

c. Field survey. The purpose of the inspectionsurvey will be to obtain general data regardingeach building to facilitate the preliminary screen-ing process. These data will include building iden-tification number, title, general function, size,general structural type (i.e., wood, concrete, steelframe, etc.), general condition, and other pertinentdata. The screening forms, such as shown inappendix F, figure F-i, sheets 4 and 5, are used toestablish a check list for the visual observations toaid field note taking. The inspection survey neednot be detailed. The time allotted for each buildingwill vary, depending on the size and complexity ofthe structure, but should be between 10 and 30minutes. A more detailed examination will bemade during the preliminary evaluation as de-scribed in chapter 4.

d. Screening. The field notes will be systemati-cally reviewed to determine the number of build-ings that will remain on the list for the prelimi-

nary evaluation process. Justifications forremoving buildings from the list include:

(1) Buildings that upon further evaluation aredetermined to fall within the intent of the inven-tory reduction criteria of chapter 2.

(2) Buildings of obviously inferior constructionor whose structural condition has deteriorated tothe point where upgrading is not feasible or costeffective. For this condition the engineer mayrecommend a course of action. As an example, abuilding with severe foundation problems, such asextreme ground settlement that resulted in footingor pile damage, may require a nonseismic evalua-tion to determine if the building should be demol-ished or repaired.

(3) Buildings that are essentially identical tostructures remaining on the list for further evalua-tion. The site inspection may indicate that groupsof buildings are similar or essentially identical. Inthis case, one building may be selected to repre-sent all the buildings in a group. The otherbuildings are then placed on hold with the decisionfor further evaluation dependent on the results ofthe analysis of the representative building. How-ever, each building must be inspected for anyserious deficiency, damage and changes to warranta separate category outside the group.

3-3. ReportA report will be prepared to summarize the resultsof the preliminary screening. The report will in-clude the following items.

a. Description of the screening process.b. Description of screening criteria.c. Description of each building surveyed, includ-

ing classification, contents, general structuraltype, condition, and available design data.

d. Results of screening such as which buildingsrequire analysis and those that were eliminatedfrom further evaluation with justification for theelimination. Identify those eliminated buildingssimilar to ones that are to have further evalua-tion. Recommendations on course of action forthose buildings eliminated from further seismicevaluation.

e. Provide a plot plan, if information is avail-able, to locate buildings included in inventory,identifying buildings eliminated from further eval-uation and those that remain on the list for thepreliminary evaluation.

f Summary table that includes building classifi-cations, structural categories, comments, and rec-ommendations.

3-2

-

TM 5-809-10-2/NAVFAC P-355.VAFM 88-3, Chap 13, Sec B

CHAPTER 4

PRELIMINARY EVALUATION

4-1. IntroductionThis chapter describes the general methodology forthe preliminary evaluation of existing buildingsusing a rapid seismic analysis. The methodology isused when there is a need to establish a prioritylisting for detailed evaluation and seismic upgrad-ing of a group of buildings vulnerable to seismicground motion. The simplified techniques provideestimates of the seismic vulnerability/damage for agroup of buildings at a fraction of the costs fordetailed evaluations. When it has been determined

Bjuildings frompreliminary screening I(Chapter )

by the preliminary screening or other actions thata building requires a detailed structural analysis,the preliminary evaluation will not be requiredand the methodology for upgrading will proceeddirectly to the procedures described in chapter 5.The methodology for preliminary evaluation issummarized in figure 4-1.

a. General procedure. The procedure describedin this chapter provides general guidelines forpreliminary evaluation, establishing priorities forupgrading, and preparing a report. An example of

Document ?eviesI (par&. 4-2a)

Assign capacityreduction factors(App. E)

a

I Site inspection(para. 4-2b) -

+Determine propertiesof existing materials(para. 4-2c(l)and App. E)1

[ Select appropriateanalytical procedurepars. 4-2c(2),(3) and _(4))

Develop capacitycurves(pars. 4-2c(S))

Select appropriatedamping ratio(para. 4-2d(2)b and Table 4-3) F- Select appropriate

risk levels(para. 4-2d(2)(a))

4Develop demand spectra(pars. 4-2d(2)) I

Estimate seismic damage4 (para. 4-2d(3) and (4))

4Other considerations(pars. 4-3) _

Combined building(para. 4-2d(S))

damageI

I Assignment of priorities(para. 4-3) _

Preliminaryevaluation reportpara. 4-4I

IDetailed structural ' < AmrvalIanalysis * -

L (Chapter 5) JFigure 4-1. Methodology for preliminary evaluation

TM 5-809-10-2/NAVFAC P-355.VAFM 88-3, Chop 13, Sec B

a preliminary evaluation is given in appendix F,figure F-i, sheet 6.

b. Naval Facilities Engineering Command RapidSeismic Analysis Procedure (RSAP). The RSAP,which is summarized in appendix D, is a variationof the procedures described in this chapter. Forexample, it provides empirical formulas for deter-mining natural periods and capacity characteris-tics, reduction factors to adjust the ultimate sitedemands, and computer programs for computingdamage estimates. These variations may not beapplicable to all buildings. Engineering judgmentand experience will be used in conjunction withthe RSAP to determine rational building struc-tural capacities and demands.

4-2. Preliminary evaluationThe preliminary evaluation provides the initialanalytical data for estimating the vulnerability ofthe selected buildings to seismic damage. This isan important consideration in determining priori-ties for upgrading within each building classifica-tion (i.e., essential, high-risk, all others). When apreliminary evaluation is prescribed, the followingbasic steps are performed: document review, siteinspection, approximation of the capacity of thestructure to resist seismic forces, approximation ofdamage by reconciliation of the structural capacitywith the earthquake ground motion demands, andrecommendations. The document review and siteinspection may not be required if all pertinent-data and conditions have been obtained in thepreliminary screening process. Generally, it willbe done concurrently if the number of buildings isnot large.

a. Document review. The available drawings,calculations, specification, and other design docu-ments obtained from the using agency will bereviewed by the engineer to identify the lateralforce resisting system and other pertinent informa-tion. The information will be summarized in aformat that can be used during the site inspectionto serve as a checklist.

b. Site inspection. A field examination of eachbuilding will be performed to determine the condi-tion of the structural elements and to evaluate itslateral force resisting system. Observations willalso be made on nonstructural elements, occu-pancy level, and value of contents. This inspectionwill be done in a more detailed manner than thepreliminary screening inspection described inchapter 3. The inspection team will include atleast one structural engineer experienced in struc-tural evaluation. Also, personnel familiar with thebuilding, such as the building supervisor or build-ing engineer, should accompany the inspectionteam to provide access to the various areas within

4-2

the building, describe functional requirements andpoint out any known areas of damage, deteriora-tion, and modification. The site inspection willnormally take one to two hours; however, the timecan increase greatly with the complexity andcondition of the building. Advance notice will berequired to arrange for inspection of buildingswith restricted access.

(1) Information obtained from the documentreview will serve as checklists during the inspec-tion.

(2) The structural and nonstructural elementsof the entire building will be examined from theoutside and inside, to the maximum extent practi-cable. In open buildings such as warehouses andmachine shops, the structural elements are fairlywell exposed. In closed-in buildings, such as officesand hospitals, structural elements are generallyhidden from view by partitions, furred walls, andhung ceilings; therefore, it may be necessary to liftceiling tiles and go into concealed spaces, closets,mechanical rooms, and other locations wherestructural elements are likely to be exposed. Ex-cept for critical cases, representative samples willbe used to establish building characteristics duringthe preliminary evaluation. Estimates will bemade on the normal number of occupants in thebuilding and the costs of the contents in thebuilding.

(3) The existing lateral force resisting systemwill be confirmed by the on-site inspection. Thevarious load paths by which lateral forces aretransferred from the roof and floor systems to theframes or shear wall systems and to the founda-tions will be determined. Appropriate documenta-tion of any discontinuity in the load paths orweaknesses in the structural connections, and anyevidence of redundancy or back-up systems andmodifications or additions to the building will bemade.

c. Capacity of the structure. The value for capac-ity is a simplified representation of the capacity ofthe overall building for a specified level of stressor distortion such as when yielding of majorstructural members occur or when lateral displace-ments reach a prescribed limit. On the basis of theavailable documents and the visual observations,the capacity of the structure to resist lateral forceswill be estimated by means of a rapid evaluationtechnique. For a large group of buildings, theevaluations should average less than one day perbuilding. More time may be spent on a representa-tive building or structural system in order toobtain data that will expedite the analysis of othersimilar buildings or systems (e.g., see para (3)below). For smaller groups of buildings wherethere is a large diversity of building types, the


average time of the evaluation may be longer. Forsome buildings that are large or complex a de-tailed evaluation is required (e.g., see last sentenceof para (2) below). For the rapid evaluation technique, the capacity is represented by a curvesimilar to the capacity curve required for method2, capacity spectrum method, in paragraph 5-5b ofSDG, except that only the points representinginitial major yielding and ultimate strength (nearcollapse) are required. An example of a capacitycurve, a modification of SDG figure 5-5, is shownin figure 4-2. General guidelines for determiningthe capacity curve are given below. An example isgiven in appendix F, figure F-1, sheets 6 through12.

(1) Determination of the lateral force capacityof a structure will include consideration of allelements, structural and nonstructural (e.g., seepara (2) below), that contribute to the resistance oflateral forces. Physical properties are generallyobtained from existing available data, otherwiseassumptions and/or tests must be made. Guide-lines for determination of the physical properties

of representative structural and nonstructural ma-terials are provided in appendix E of this manual.The analysis must include the evaluation of themost rigid elements resisting the initial lateraldistributions, as well as the more flexible elementsthat resist the lateral distortions after the rigidelements yield or fail. Consideration must also begiven to the interaction of various combinations ofthe structural framing systems and elementswhich will contribute to the resistance of thelateral loads.

(2) The capacities are generally determined bymanual calculation methods. The methods usedwill vary for different types of buildings andlateral force resisting systems. For shear wallsystems, a shear capacity is assumed and anadjustment is made for the flexural capacity thatis dependent on the height-to-depth ratio of thepiers. For reinforced concrete frame structures, asimilar procedure is used to relate the capacitydue to flexure of the columns to the capacity dueto shear strength in the columns. For steel milltype buildings, the capacity of the steel frame is

3000

V%.

:I

c

cn

2000

1000

00 5 TO

DISPLACEMENT AT ROOF, dN (inches)

Modified from SDG fig 5-5

Figure 4-2. Force-displacement capacity curve

4-3

TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chop 13, Sc B

dependent on the fixity of the column base. Forbraced frames, L/r and connections are generallythe critical items. The horizontal diaphragm sys-tem will be evaluated for its capacity to transferlateral forces to the vertical resisting elements. Ifthe structure consists of a structural steel frameand nonstructural infill brick walls, the brickmust yield and then fail before the steel frameacts. If a system consists of nonstructural brickwall elements and structural steel X-bracing ele-ments, both systems of elements will work untilthe brick fails, and then the X-bracing will takethe load until it fails. For some buildings, becauseof size or complexity, approximate manual calcula-tions may not be adequate to establish reliablecapacities for lateral loads. In these cases, eitherthe procedure described in paragraph (3) belowshall be used or the building shall have thedetailed structural analysis described in chapter 5.

(3) In some cases, a more detailed analysismay be made for one building (or part of abuilding) that is representative of several otherbuildings. The results can be extrapolated to ana-lyze other buildings constructed similarly. Forexample, there may be many multi-storied rein-forced concrete warehouse type buildings with flatslabs, drop panels, and column capitals for interiorframing and reinforced concrete walls with largewindow openings for exterior framing. Computerruns using simplified idealized models can bemade to establish guidelines for lateral stiffnesscharacteristics and stress distributions of typicalframes of a representative building. The resultscan be extrapolated to analyze the other buildingswith this warehouse type of construction. A simi-lar procedure can be used to establish guidelinesfor multi-leveled, high-low roof, mill type steelbuildings.

(4) The results of the capacity evaluation areexpressed in at least two of the following threeterms that represent the overall building.

(a) The base shear coefficient (CA). CB isequal to the base shear capacity divided by theeffective weight of the building (V/W). CB isanalogous to the ZIKCS of the BDM, except thatCB represents a capacity value and ZIKCS repre-sents a design value.

(b) Lateral displacement at the top of thestructure (dN). dN is the displacement at the top ofthe building resulting from the application of thelateral forces associated with CB.

(c) Fundamental period of vibration of thestructure ( that is consistent with the values of CBand dN. T is generally calculated from a Rayleighmethod of analysis such as formula 3-3 of theBDM; however, in some cases, a value may beassumed based on empirical data.

(5) Two capacities are required for each of theprincipal directions of the building. One capacityrepresents initial major yielding (e.g., point A infig 4-2) and the other represents the ultimatestrength or near collapse state (e.g., point D in fig4-2) of the lateral force resisting system. The CB,dN, and T values are used to determine spectralacceleration (S.) and spectral displacement (Sd) asdescribed in SDG capacity spectrum method, para-graph 5-5b, and illustrated in table 4-1.

(6) A table is used to summarize the capaci-ties of a large group of buildings.

d. Damage estimates. A graphical reconciliationbetween the earthquake demand (site responsespectrum) and the building capacity is used toestimate the amount of damage that will occurduring a postulated earthquake. The procedure isessentially the same as the Capacity SpectrumMethod prescribed in SDG paragraph 4-4d anddescribed in SDG paragraph 5-5b. In the SDG, theobjective is to determine if the building willremain functional during EQ-II and to approxi-mate the lateral deformations (para 4-4d (7)). Inthe evaluation procedure, the objective is to esti-mate the damage ratio for EQ-IH.

(1) Capacity spectrum. When the capacity isplotted in terms of V and dN, as shown in figure4-2, it is similar to the force-displacement curvesused to represent strength of materials; however,instead of plotting the results of a single testelement, the curve represents the global capacityof the overall structure. When the V and dN areconverted to S. and Sd, the shape of the curveremains similar, but the units change. S. isessentially proportional to V, with some variationsdue to story mass distribution and modal partici-pation factors and Sd is essentially proportional todN. The capacity curve can also be expressed in -

terms of S. and T and Sd and T, as shown in figure4-3. The conversion process is shown in table 4-1.A plot of S. (acceleration) vs Sd (displacement) forthe overall building as illustrated in figure 4-3 isanalogous to a force (mass times acceleration) vsdisplacement curve for a structural material. Thesecant stiffness of the S. vs Sd curve is analogousto the secant modulus of the stresses and strainsrepresenting a force-displacement curve. T, whichrepresents the mass and stiffness characteristics ofthe structure, is approximated by using the secantstiffness of the S. vs Sd curve.

(2) Demand spectra. The demands of earth-quakes are represented by response spectra. Re-sponse spectra are obtained by using proceduresdescribed in SDG, chapter 3. They are usuallyplotted in terms of S. and T (e.g., see SDG fig 2-8)or on a log-log-log tripartite curve which givesvalues for S., Sd, S, (spectral velocity) and T, as

4-4

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec BTable 4-1. Calculation of S. and Sd capacity values

Point V dN VV/W PFN a Sa Sd T

(kips) (in) (in) (sec)

A 2200 2.3 0.22 1.30 0.78 0.280 1.77 0.80

D 3000 8.7 0.30 1.26 0.83 0.361 6.90 1.40

V/W: V - Base shear, W Weight - 10,000 Kips

dN = Lateral roof displacement due to V

PFN = (Gmo) (4N)/(Emt2), modal roof participation factor

a = (Emf) 2/(Em)(Qmf2), effective modal eight

S& X9 Spectral acceleration VW a

Sd = Spectral displacement dN PFN

T = 2w VSdl(Sa)(g) , fundamental period of vibration

Emo = Summation of story mass times mode shape factor from the roofto the base of the building

From SDG Table 5-4

shown in figure 4-4. From the tripartite plot, datacan be obtained to plot the curve in terms of Sdand T and S. and Sd, as shown in figure 4-5.These relationships are consistent with the dy-namic analysis formula:

Sd = S. (T/2irg (eq 4-1)where g is the acceleration of gravity and S. isexpressed in units of g.

(a) Risk eveL The site response spectra forthis evaluation will be representative of groundmotion for EQ-II as defined in the SDG.:

(b) Damping. A set of damping values foreach building, as a percentage of critical damping,will be determined from table 4-2. These dampingvalues will be used to define the response spectrarepresenting the ground motion described in para-graph (a), above.

(3) Capacity versus demand. The capacitycurve and the demand curve are plotted on thesame graph. Their intersection is considered to bethe reconciliation between demand and capacity.

The demand is represented by two curves: onerepresents elastic damping for periods less thanthe elastic period of the building and the otherrepresents damping at the ultimate capacity. Atransition line is drawn connecting the two curvesbetween the elastic period and the ultimate capac-ity period. The procedure is identical to Method 2,Capacity Spectrum Method, of the SDG, exceptthat the preliminary evaluation uses a more ap-proximate capacity curve. An example, which is amodification of SDG figure 5-6, is shown in figure4-6.

(4) Percent damage. To estimate the amount ofdamage a building experiences from an earth-quake, damage must first be defined. Until theyield capacity of the structure is reached, damageis assumed to be zero. When the ultimate capacityis reached, damage is assumed to be 100 percent.For intermediate values of capacity, the assess-ment of damage is necessarily somewhat subjec-tive and depends on many factors not amenable to


sa 9

0

Ul tiate N

Dust~~~ I 1inear,tYield

(a)

Elastic

l l * __. - Of~~~~~~~~~O

I S oIn

I |

I i- S

S d In.

I I,/"I /. __

r- - - - - - - -o --

II

II

_ .

Ul timate N

-1 '' YieldI/I

(b) I

-Elastic Il

_.1._

IT, Sec.

iUl tima

-i- -

I9

II

(c)

Yield

T, Sec.

FAgre "S. Capaciy spectrum curves

analytical treatment. In lieu of a better alterna-tive, it is assumed that damage varies linearlybetween the yield limit and the ultimate limit.The increase in damping beyond the elastic limitcan be related to the effects of increased internalenergy absorption (e.g., hysteresis loops) and thenonlinear effects (e.g., reduction in harmonic am-plification) of the building response. In lieu of abetter alternative, damping is also assumed toincrease linearly between the yield limit and theultimate limit values. The percent of damage isestimated from the graphical solution by takingthe ratio of the length between the damage recon-ciliation point and the yield point (length d) to the

length between the yield point and the ultimatecapacity (length c), as shown in figure 4-6. Thisprocedure is done for each of the principal direc-tions of the building.

(5) Combined building damage estimate. Foreach building, the damage is computed for each ofthe principal directions of motion, longitudinal andtransverse. To determine the combined damage forthe two directions, it is assumed that one-third ofthe building depends on each direction of lateralresistance and the remaining one-third depends onboth directions for lateral resistance. That is, if astructural element required for both directions forlateral resistance is damaged by one direction of

4-6


FREQUENCY - HZ

1000, I .a I

:0.0I .II I .I II I I I I I

100.0-J

I i I- A F\ KtX'X A'YN± ,F A�"N ^ '.-t' ' ,' i 14 x NNNV',r.. /C

- .

. - . . . . 0 F . @ . - P_ 0 v b P + S . P x

.nN/$tX AN IXiNNNX�N-'7AX. ANIJN'tiflŽY�Z N-Ia*AI

'4.0*'/.,7 ,' K N1tXx'A 7/' K( \'

UOaon

i

I

t

WYb

IZ

0

Si-

0

'A"IL

30.0

1.0

0.1

m v ^~~~~5% Damp i n i

I xi NL

| X Ompne . /

/KN e ' .

t///~~~~ I < X ZE v,\ I ,//AD,/ A qviKo]

/Ne,1 V\ I li~ ~ &/ z~~<i~~~~~~~~~~~~~i~~~7 X, '4

'It

0'4

'04

4jb~

*4 \

a"

*0.

-41

/> IN

I4.K syN.' xS SI

A~r,0.01

0.1oC

- . - a i - i -

II 0.I .o 30.0

PERIOD-SEC

Figure 4-4. Tripartite plot of reaponse spectra shown in SDG figure 2-8

motion, it is also damaged in the other direction. directions, the combined damage is 50 percent.The procedure takes two-thirds of the damage of (6) Damage vs earthquakes. The procedure re-the more critical direction and one-third of the quires damage evaluation for ground motion repre-damage of the other direction to determine the sented by EQ-fl as prescribed in paragraphcombined damage. For instance, if the damages 4-2d(2Xa). Damage estimates can also be deter-are 60 percent and 30 percent in the two principal mined, with little additional effort, for smaller

4-7


0.

Od-

03. ~~03

0.2 02

0, . . . . I .s02 4 6 8 VI 0

Sd (in)

8C 6

// VI 4

2

£ ~~~~~0

Figure 4-5. Response spectrum pl

earthquakes that have a higher probability ofoccurring at the site. For example, these smallerearthquakes. may include response spectra repre-senting and/or Vi the amplitudes of EQ-U.Sample results are shown in appendix F figureF-1, sheet 12. Damage estimates for these smallerearthquakes may be necessary in some cases to aidin establishing upgrading priorities between thevarious buildings. For example, Building A maybe very sensitive to the size of the earthquakesuch that for EQ-Il it has 100 percent damage,but for % of EQ-IH it has no damage. Building B isestimated to have 80 percent damage at the EQ-fldemand, 60 percent damage at % of EQ-I, and 20percent damage at of EQ-fl. In this example, forany earthquake up to of EQ-fl, Building Aperforms better than Building B (no damage com-pared to up to 60 percent damage). Only in theevent of EQ-fI does Building B perform better

DG fig 2-8

to 30

T(sec)4.0

l

1.0 2.0 3.0

T (s c)

otted in terms of Sd us T and S. us Sd

than Building A (80 percent damage vs. 100percent damage). Thus, a conclusion may be madethat Building B has a higher priority for upgrad-ing than Building A.

e. Results of the preliminary evaluation. Theresults for all the buildings will be summarized intabular formats for ease of comparison. An exam-ple is shown in appendix F, figure F-1, sheet 12.These tabulations show estimated damage interms of percentages. If replacement cost data areavailable, such as from the inventory data base,damage can be shown in dollar costs.

4-3. Priorities for upgradingThe cost associated with a building's vulnerabilityto seismic damage within each building classifica-tion is an important economic consideration in theassignment of priorities for seismic upgrading.Other considerations must also be evaluated in the

4-8

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec BTable 4-2. Damping values of structural systems

Structural System Elastic-Linear Post Yield

Structural Steel

Reinforced Concrete

Masonry Shear Walls

Wood

Dual Systems

3'

5'

7'

10%

(1)

7%

10%

12%

15

(2)

1. Use the value of the primary, or more rigid, system. If both

systems are participating significantly, a weighted value, pro-

portionate to the relative participation of each system, may be

used.

2. The value for the system with the higher damping value may be

used.

From SDG Table 4-1

assignment of priorities when limited funds areavailable. These considerations will include: poten-tial damage to building contents (e.g., a relativelyinexpensive warehouse structure may contain veryexpensive electronic equipment that could be seri-ously damaged by failure of the building); impor-tance of the function performed by the building tothe mission of the installation; number of occu-pants normally within the building; redundancy(i.e., are there viable alternatives for performanceof the function if the building is lost? For example,an urban area may have three or more buildingsthat perform an essential function, but the tempo-rary loss of function of one building could be offsetby the services of the others). The relative weight-ing of each of the above considerations is some-what subjective and may vary from one installa-tion to another and therefore should be establishedin collaboration with a designated representativeof the using agency.

4-4. ReportA report will be prepared to summarize the results

of the preliminary evaluation. The report willinclude the following items.

a. Description of preliminary evaluation process.b. Observation on nonstructural elements, occu-

pancy, and contents.c. Prioritization criteria and weighting factors

used.d. Criteria for determining which buildings re-

quire further analysis and for justifying no furtheranalysis.

e. Method of analysis for each structural type.f Description of each building analyzed includ-

ing lateral force resisting system, assumed struc-tural properties, etc.

g. Copies of the capacity spectra with the graph-ical estimation of structural damage.

h. Prioritization of buildings within each classi-fication.

L Results of analys, s that include building dam-age assessments, list of buildings requiring furtheranalysis, and list of buildings not requiring fur-ther analysis.

4-9


1.0

0.9

X o. \\ I Transition ZoneI to 2_G Oamping

0.5

U

Deand aayi

a.

Capacity Etnae

0 0.5 1.0 1.5 2.0 2.5

Period,.T (sec.)

Figure 4-6. Capacity spectrum method for preliminary evaluation

4-10


CHAPTER 5

DETAILED STRUCTURAL ANALYSIS

5-1. IntroductionThis chapter prescribes acceptance criteria anddescribes general procedures for detailed struc-tural analysis of existing buildings. Guidelines areprovided for determining the capacity of the exist-ing structure to resist seismic forces. The detailedanalysis is performed on buildings that have beenselected as a result of the evaluation and/or priori-ties (chapter 4) established by the approval author-ity or on buildings as directed by higher authority.The purposes of the detailed structural analysisare to determine if the building satisfies theacceptance criteria or if it requires seismic upgrad-ing, and if it requires seismic upgrading to iden-tify the deficiencies and to recommend alternativesfor the upgrading (chapter 6). The methodology forthe detailed structural analysis is summarized infigure 5-1.

5-2. Acceptance criteriaThe acceptance criteria for the seismic resistanceof existing buildings will be essentially as pre-scribed for the post-yield analysis for EQ- inparagraph 4-4 of the SDG. If an existing buildingdoes not conform to the above criteria some lati-tude is provided in the following paragraphs inrecognition that seismic upgrading is an expensiveand disruptive process and it may be more cost-effective to accept an existing building that ismarginally deficient rather than to enforce strictadherence to the criteria.

a. Conforming systems and materials. Whenthe lateral force resisting structural systems andmaterials are in compliance with the requirementof tie BDM (Refer to BDM paragraph 3-6 forapproved structural systems and to BDM chapters3, 5, 6, 7, and 8 for material requirements), theearthquake demand represented by the EQ-IHresponse spectra may be reduced by a maximum of15 percent (i.e., to 0.85 EQ-fl) and the driftlimitations for EQ-II will remain the same asprescribed in SDG paragraph 4-4e(2Xa) (i.e., storydrift ratio 0.010 for essential and 0.015 for others).

b. Nonconforming systems and materials. Whenthe lateral force resisting system or the structuralmaterials do not conform to the approved systemsand material specifications of the BDM, justifica-tion for acceptability of the existing systems and/or materials is required. Requirements for sub-stantiated data are prescribed below. Acceptanceof the approval agency is also required.

(1) Structural systems not specified in theBDM and/or SDG (e.g., "nonductile" moment resis-tant reinforced concrete frames and unreinforcedmasonry shear walls) require an analytical evalua-tion report. The report will include data for estab-lishing the capacity of the system to resist seismicloads and justification for the performance of thesystem satisfying the intent of the BDM and SDGprovisions.

(2) Structural materials not satisfying theminimum requirements of the BDM and SDGrequire an evaluation report. Guidelines are pro-vided in appendix E.

(3) The acceptance criteria for the substanti-ated noncomplying structural systems and materi-als are the same as prescribed in paragraph a,above, except that the drift will not be allowed toexceed 60 percent of the drift limits prescribed forconforming systems and materials.

c. Alternative acceptance criteria. In lieu of theabove acceptance criteria, at the option of theapproval authority, the acceptance criteria for theseismic resistance of specific existing buildings,namely other than essential buildings in seismiczones 3 and 4, may be satisfied by conformancewith the provisions of the BDM or the Static CodeProcedure of appendix C.

5-3. Methodology for the analysisThe detailed structural analysis follows a proce-dure similar to that used for the preliminaryevaluation for determining the capacity of thestructure to resist seismic loads, except that theanalysis is done in greater detail and with moreaccuracy in order to increase the reliability ofrecommendations for acceptability or upgrading.The procedure extends beyond the scope of thepreliminary evaluation by identifying deficienciesand evaluating the effects of correcting deficienciesto improve the overall performance capabilities ofthe building.

a. Document review. Available drawings, cal-culations, specifications, and other design and/orconstruction documents will be reviewed in detailfor pertinent information that will aid in thedetailed structural analysis. Items not covered bythe available documents and required to completea detailed analysis will be investigated during thesite inspection.

b. Site inspection. A detailed site examinationwill be performed to confirm data contained in theavailable design and construction documents and

5-1


r -'I Building selected fo II detailed analyals

I -

I Detailed document revieu -

Develop desSgn I,---xconcepts I

I(chapter 6)1 __ _

Figure 5-1. Methodology for detailed structural analysis of buildings

the results of any previous inspection and evalua-tion reports. Special attention will be given toverify the existing lateral force resisting elementsand systems (e.g., note any missing bracing mem-bers, openings not shown on the drawings, andadditions). Testing or special inspection will bemade when there is no available data or when

as-built conditions are suspect.c. Testing of existing materials. When econom-

ically justified, a testing program may be estab-lished to determine the capacity characteristics ofnonconforming materials and details, especiallywhen the acceptability of test results can make thedifference between accepting an existing building

5-2

TM 5-809-1O-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sac B

in an as-is condition as opposed to requiring acostly modification. Structural capacities of exist-ing materials will be determined in accordancewith criteria and testing requirements of appendixE.

d. Capacity of the structure. The capacity ofthe structure to resist lateral forces will be deter-mined in accordance with the guidelines providedin the SDG for new construction with the modifica-tions provided in this manual to cover existingmaterials and structural systems (Refer to para5-2 for acceptance criteria).

e. Demands of the earthquake. The structurewill be subjected to the demands of EQ-II, asdefined in the SDG.

f Evaluation of structure. The structure willbe evaluated by a capacity/demand comparison inaccordance with the SDG procedures for designingfor EQ-I (refer to SDG paras 4-4 and 5-5), usingmethods 1 or 2 as described below. Examples ofprocedures are given in SDG appendix E.

(1) Method 1: Elastic analysis procedure(refer to SDG para 4c). This procedure is used todetermine if the existing structure has the re-quired capacity to resist the prescribed earthquakecriteria. Table 5-1 is an extended version of SDGtable 4-2, inelastic demand ratios.

(a) If the structure meets the acceptancecriteria of paragraph 5-2 above and does not haveany of the deficiencies listed in paragraph 4c(5)of the SDG, upgrading is not required.

(b) If the structure does not conform to theacceptance criteria by means of the Method 1analysis, seismic upgrading will be required unlessit can be demonstrated that the building cansatisfy the acceptance criteria by means of Method2, capacity spectrum method.

(2) Method 2: Capacity spectrum method(refer to SDG paras 4d and 5-5b). This proce-dure is used to compare to earthquake demand asrepresented by an appropriate response spectrumwith the structural capacity as represented by acapacity spectrum with accelerations, S., thebuilding can resist when it has fundamental peri-ods, T.

(a) If the structure conforms to the accep-tance criteria of paragraph 5-2 with the Method 2analysis, upgrading is not required.

(b) If the structure does not conform to theacceptance criteria with the Method 2 analysis,upgrading will be required.

g. Identify deficiencies for structures that areselected for seismic upgrading. The results of thedetailed structural analysis from Method 1 orMethod 2 will be used to identify the structuraldeficiencies.

(1) For Method 1, in most cases, structuraldeficiencies will be identified as those that exceedthe allowable inelastic demand ratios given intable 5-1, which is an extended version of table4-2 of the SDG. The results of the Method 1analysis will also be evaluated to identify otherdeficiencies indicated in paragraph 4-4c(5) of theSDG.

(2) For Method 2, in most cases, structuraldeficiencies will be identified as those membersthat limit the capacity of the structure below thelevel required by the earthquake demand becauseof inelastic yielding or rotation. However, careshould be exercised in the determination of thestructural capacities to confirm that the possibilityof the other deficiencies indicated in paragraph4-4c(5) of the SDG have been properly consideredin the determination of the structural capacity.

(3) For both Method 1 and Method 2, supple-mentary structural analyses, as described in theBDM for new construction, must be performed todetermine the structural adequacy of an existingbuilding or to identify possible deficiencies. Theseanalyses include:

(a) Evaluation of foundations for verticalbearing and the transfer of horizontal forces to thesoil.

(b) Evaluation of floor and roof diaphragmsfor shear capacity and shear transfer to verticalresisting members. Also adequacy of diaphragmchords and collector members.

(c) Out-of-plane bending of vertical wallsand piers, including anchorage and support atDoor and roof levels.

(d) Adequacy of support and anchorage ofequipment, piping, and nonstructural elements asdescribed in chapter 9.

(e) Adequacy of bracing or lateral supportsto preclude local buckling of steel members.

(1) Check of P-delta effects (see SDG para5-5d for additional guidance), local torsion andother secondary stresses.

5-4. RecommendationsOn the basis of the detailed structural analysisresults, recommend alternatives for seismicupgrading.

TM 5-809-102/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec BTable S-1. Inelastic demand ratios for existing buildings. (Sheet I of 2)

Building System Element Essential High Risk Others

a. Systems conforming to BDM requirements.

Steel

DMRSF BeausCo lumns*

2.01.25

2.51.5

3.01.75

Braced Frames

Tie Rods

BeamsColumns*

Dx';~c~:Us**Dig. Br c

Conaections

1.51.251.251.01.0

1.751.51.51.251.25

2.01.751.51.251.25

Tension only 1.0 1.1 1. 25

Concrete

DHRSF BeamsCo lumns*

2.01.25

2.51.5

3.01.75

alls$:

(1) Single curtainof reinforcing

(2) Double curtainof reinforcing

ShearFlexureShearFlexure

1.11.51.252.0

1.251.751.52.5

1.52.01. 753.0

Diaphragms

Masonry Walls

ShearFlexure

1.251.5

1.51.75

1.752.0

ShearFlexure

1.11.5

1.251.75

1.52.0

Wood TrussesColumfs*Shear Walls andDiaphragms

Comnectioni(other than ails)

1.51.25

2.0

1.2S

1.751.5

2.01.75

2.50 3.0

1.50 2.0

*In no case vill axial loads exceed the elastic buckling capacity.**Full panel diagonal braces vith equal nuaber acting in tension and compression for

*pplied lateral loads.I-bracing and other concentric bracing systems that depend on compression diagonalto provide vertical reaction for tension diagonal.

Sheet 1 of 2

5-4

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Soc BTable 5-. Inelastic demand ratios for eisting buildings. (Sheet 2 of 2)

Building System Element Essential Kish Risk others

b. Systems not conforming to DM requireaents.+

Concrete Frames Beams 1.25 1.5 1.75Column* 1.0 1.25 1.25

Unreinforced Concrete Shear 1.0 1.1 1.25Walls Flexure 1.0 1.0 1.0

Unreinforced Maeonry Shear 1.0 1.1 1.25Walls Flexure 1.0 1.0 1.0

*In no case will axial loads exceed the elastic buckling capacity.*See also paragraph 5-2b for additional acceptance criteria for nonconformingstructural systems.

Sheet 2 of 2

5-5


CHAPTER 6

DEVELOPMENT OF DESIGN CONCEPTS

6-1. IntroductionThis chapter describes general procedures for thedevelopment of design concepts for the structural

upgrading of existing buildings to comply with theacceptance criteria prescribed in chapter 5. Guidelines are provided for the upgrading of the struc-tural systems, the determination of the capacities

- --Ialdi.g. frm detailed stnuctural nalysiI

(chapter ) _ __L_ . I

Cost/ef it aalysis…- Aupr-

_L( V i-rI T __ it ____

Figure -1. Methodology for development of design concepts for seismic upgrading

6-1


of new structural elements, and development ofstrengthening techniques. The methodology for theprocedures contained in this chapter is indicatedin the flow chart in figure 6-1.

6-2. Acceptance criteriaThe design criteria for the development of conceptsfor seismic upgrading of existing buildings will bein accordance with the applicable provisions of theBDM and/or the SDG as required for new construc-tion. Unless otherwise directed by the approvalauthority, the minimum acceptance criteria for theconceptual designs will be as indicated in para-graph 5-2 for the detailed structural analysis. Theobjective of seismic upgrading will be to establishfull compliance with SDG provisions for the EQ-ilpost-yield evaluation (refer to SDG paragraphs 4-4and 5-5) or, when so directed by the approvalauthority, the applicable provisions of the BDM orappendix C. In most cases the costs associatedwith full compliance, as opposed to the reducedforce levels permitted by the minimum criteria,will be negligible. However, the allowable reduc-tion will provide a margin for acceptance in thosecases where strict adherence to the unreducedcriteria would result in much more expensive ordisruptive procedures (e.g., a 15 percent reductionin the EQ-II response spectra may make it possi-ble to accept an existing building withoutstrengthening the existing foundations or the con-struction of an additional shear wall; however, ifeven with the reduced criteria foundationstrengthening or a new wall is required, theupgrading design will be in compliance with theunreduced criteria).

6-3. Development of concepts for seis-mic upgrading

The results of the detailed structural analysisprescribed in chapter 5 will identify, for a givenbuilding, the deficiencies with respect to the accep-tance criteria of the various structural elements orsystems. These results will be carefully reviewedin the development of alternative design conceptsto upgrade the structure to meet the acceptancecriteria. Three alternative concepts will be devel-oped for each building unless justification can beshown for fewer alternatives (e.g., it may be shownthat the obvious cost effective solutions for adeficient steel braced building are either to replacethe existing bracing with stronger bracing mem-bers, or to add new bracing so that only twoalternatives need to be developed). Each conceptwill be developed to the extent that will permit areasonable cost estimate to be made. The extent ofremoval of existing construction will be indicated;the sizes and locations of new, replaced, or

strengthened structural members will be indi-cated; typical structural connections will be shown;and the extent and schematic details for upgradingnonstructural elements will be indicated.

a. General considerations In addition to theacceptance criteria of paragraph 6-2, the followinggeneral considerations will be addressed in thedevelopment of the design concepts:

* Structural systems* Plan configuration* Horizontal diaphragms and foundation ties* Eccentricity* Deformation compatibility of new and exist-

ing materials* Inelastic demand ratios* Drift limits* Base isolation and energy dissipation(1) Structural systems. The development of the

structural upgrading concept requires a completeunderstanding of the existing vertical and lateralload resisting systems of the existing building. Thedesigner must be able to determine the conse-quences that the removal, addition, or modificationof any structural or nonstructural element willhave on the performance of the strengthenedbuilding.

(a) Gravity load resisting system. An evalua-tion of the existing vertical load carrying struc-tural system will be made to determine the effectsthat the seismic upgrading may have on futureperformance of the building to resist dead and livegravity loads. The evaluation will include a de-scription of the components of the vertical loadcarrying system and the load path from the sourceof the dead and live loads to the foundations.

1. Floor and roof framing. In most build-ings, the horizontal framing systems (i.e., floorsand roofs) will participate in the lateral forceresisting system as a diaphragm in addition tosupporting the gravity loads. As part of the seis-mic upgrading, the floor and roof systems mayrequire modifications (e.g., superimposed dia-phragms or horizontal bracing) that will add to thedead load; thus, the capacity of the modifiedsystem must be evaluated for the new loadingconditions.

2. Vertical structural elements. Verticalload resisting elements such as columns, bearingwalls, and framing systems, may also be affectedby the seismic upgrading. In addition to the addedweight that may be imposed due to the seismicstrengthening, these elements may participate inthe lateral force resisting system. For example,bearing walls may also be used as shear walls andframes may be strengthened or braced to resistseismic forces. If these framing elements are not

6-2

TM S-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

used for the lateral force resisting system, theywill have to be analyzed for deformation compati-bility. This analysis will include the effects of thelateral displacements due to extreme seismic mo-tion on the vertical load carrying capacity of thevertical structural elements.

3. Foundations. If the seismic upgradingadds weight or redistributes the existing gravityloads, the foundations must be analyzed for theadditional gravity loads combined with the hori-zontal and overturning forces associated with theseismic lateral force design.

(b.) Lateral load resisting systems. Thestructural system that is designed to resist theseismic forces basically relies on a complete three-dimensional space frame; a coordinated system ofshear walls or braced frames with horizontal dia-phragms; or a combination of both. Descriptions ofthese basic systems and their components for newconstruction can be found in the BDM, paragraph2-9. In the evaluation and upgrading of an exist-ing structure, it is sometimes difficult to identifyan existing lateral force resisting system. Innova-tive analytical procedures and reliance on existingmaterials and systems that are not generallyconsidered for new construction are required todetermine the load paths and capacities of theexisting structures. When an existing structure isnot adequate to resist the prescribed lateral forces,as determined by the detailed structural analysisdescribed in chapter 5, strengthening of the exist-ing lateral force resisting system will be required.

(2) Configuration. If the existing building ishighly irregular in plan configuration or is com-prised of units with incompatible seismic responsecharacteristics (e.g., a flexible 6-story steel mo-ment frame connected to a 3-story rigid concreteshear wall unit), severe problems that cannot beresolved by strengthening or upgrading could de-velop at the connection between two units. In suchcase§, consideration should be given to separatingthe two units with a structural expansion joint.Each unit should have a complete system forresisting vertical as well as lateral loads. Struc-tural members bridging the joint with slidingsupports on the adjacent unit should be avoided.The criteria for building separations in the SDG(par 4e(2Xb)) apply also to existing buildings.Expansion joints should provide for three-dimensional uncoupled response of each of theseparate units of a building, but need not extendthrough the foundations.

(3) Horizontal diaphragms and foundationties. Every upgraded existing building will haveeither a rigid or semi-rigid horizontal floor dia-phragm as defined in Chapter 5 of the BDM. Roofdiaphragms may be flexible or semi-flexible pro-

vided they comply with the applicable require-ments specified for those diaphragms in the BDM.Foundation ties between pile caps and caissonswill be provided in accordance with paragraphs3-3(J)3c and 4-8 of the BDM. Existing diaphragmsand foundation ties that do not comply with theserequirements will be strengthened or replaced inaccordance with the guidelines of paragraph 6-4,unless proper justification can be provided forwaiving the deficiency.

(4) Eccentricity. Provisions shall be made forthe increase in shear resulting from the horizontaltorsional moment due to an eccentricity betweenthe center of mass and the center of rigidity, asprescribed in BDM paragraph 3-3(e)4 and SDGparagraph 4-3e(5). In the development of upgrad-ing concepts for existing buildings, when the verti-cal shear resisting elements must be strengthened,supplemented, or replaced with new elements,consideration will be given to location of new orstrengthened elements so as to reduce any eccen-tricity between the center of rigidity and thecenter of mass.

(5) Deformation compatibility of new and exist-ing materials. The compatibility of the deformationcharacteristics of the existing elements and thenew strengthening elements will be considered inthe strengthening design of the building.

(a) Relative rigidities. When lateral forcesare applied to a building, they will be resisted bythe various elements in proportion to their relativerigidities. The lateral stiffness of a structure iscalculated on the basis of the deformation charac-teristics of the lateral force resisting elements. Thestructure may be flexible (e.g., a light steel frame)or rigid (e.g., a structure with thick masonrywalls). If the structure is to be strengthened toresist seismic forces, the new structural elementsmust be more rigid than the existing elements ifthey are to take a major portion of the lateralforces and reduce the amount of force that is takenby the existing elements. Both the relative rigidi-ties and strengths of all lateral force resistingelements must be considered. To illustrate, thefollowing two examples are given:

1. Existing steel moment frame strength-ened by diagonal steel bracing. Assume an exist-ing steel moment frame building that has a one-inch story displacement due to seismic forces.Diagonal bracing is added to the moment framesto reduce the lateral displacement to 0.1 inch forthe same force level. Thus, it can be estimatedthat the bracing resists about 90 percent of thelateral force and the frame resists about 10 per-cent. If the original moment frame can safelyresist 10 percent of the seismic forces, the bracingsystem is effective. (Note this example neglects the

6-3


possible increase in the magnitude of the seismicforces due to a decrease in the period of vibration.)

2. Existing brick building strengthenedby a steel braced frame system. Assume an exist-ing brick building that has a 0.01-inch storydisplacement due to seismic forces. A steel bracingsystem is added that has a 0.02-inch story dis-placement for the same force level. In this case, itappears that after strengthening the building, thebrick walls will resist approximately two-thirds ofthe lateral forces until they fail and transfer loadto the steel braced frames. Therefore, the steelbracing system is fully utilized prior to cracking ofthe brick walls; however, if it subsequently canresist the total seismic forces, it will limit thelateral displacements and prevent excess damageto the brick walls (see subpara (7) below for driftlimitations).

(b) Deformation characteristics of structuralelements. The accuracy of the relative rigiditycalculations is dependent on the accuracy of theassumptions used for determining the stiffnesscharacteristics of each element or system. Whenall of the lateral force resisting elements are of thesame material and have similar deformation char-acteristics (e.g., flexural and/or shearing deforma-tions), the relative rigidities can be calculated withreasonably good accuracy. However, when there isa variety of materials and cross-sectional shapes,the confidence level on the accuracy of the relativerigidities is greatly reduced. When the confidencelevel is low, the range of stiffness values should beenveloped and the distribution should be over-lapped to account for the inaccuracies. Mathemati-cal modeling guidelines are given in SDG para-graphs 54b and 5-5a(2). Structural elements thatrequire special consideration in determination ofrelative rigidities include:

Concrete: cracked vs. uncrackedShear walls: participation of intersecting

walls (e.g., effective flange widths) and effects ofopenings.

Steel frames: participation of concrete fire-proofing, floor slab and framing, and infill walls(structural and nonstructural).

(c) Evaluation of structural elements not partof the lateral force resisting system. Structuralelements that are not part of the lateral forceresisting system will be evaluated for the effects ofthe deformation that occur in the lateral forceresisting system. These provisions for the EQ-Ildeformations parallel the deformation compatibil-ity provisions in BDM paragraph 3-3(J)ld.

(d) Protection of existing brittle elements.Brittle elements that are not part of the lateralforce resisting system are susceptible to damage ifthey are forced to conform to the deformations of

the lateral force resisting system. In order toprotect these elements from the possibility of beingsubjected to large distortions, provisions can bemade to allow the structural system to distortwithout forcing distortion on the brittle elements.An example of isolating a masonry wall from theslab soffit is shown in the BDM, figure 9-1. Whenrigid walls are locked in between columns, asimilar method of isolation may be required ateach end of the wall.

(6) Inelastic demand ratios Seismic capacity,demand, and inelastic demand ratios shall becalculated in accordance with the provisions ofchapter 4 of the SDG and shall not exceed thevalues given in table 5-1 unless they are sup-ported by other systems that can resist the re-quired lateral forces. For example, in an existingunreinforced masonry bearing wall building withnew reinforced concrete shear walls or steel brac-ing, the masonry walls are assumed to share thelateral forces in proportion to their relative rigidi-ties until the allowable inelastic demand ratio forreinforced masonry is exceeded. At that point, theentire story shear must be resisted by the newshear walls or steel bracing. The masonry wallmay be assumed to be capable of supporting theimposed vertical loads, providing the drift limitsspecified in the following subparagraph are notexceeded.

(7) Drift limits. Lateral deflections, or drift, ofa story relative to its adjacent stories for EQ-flwill be in accordance with the provisions of para-graph 5-2a, except that for unreinforced concreteor masonry walls and nonductile reinforced con-crete frames where the allowable inelastic demandratios are exceeded (see subpara (6) above), theinterstory drift limits for the EQ-IH forces will bereduced to those given in paragraph 5-2b (i.e., 60percent of para 5-2a) unless the above nonductileelements are properly anchored to a new struc-tural system (i.e., reinforced concrete or masonrywall, braced steel frame, etc.) that is capable ofresisting the entire story shear.

(8) Base isolation and energy dissipation.(a) Base isolation. Design strategies that

significantly modify the dynamic response of astructure at or near the ground level, are generi-cally termed base isolation. This is usuallyachieved by introduction of additional flexibility atthe base of the structure. The objective is to forcethe entire superstructure to respond to vibratoryground motion as a rigid body with a new funda-mental mode based on the stiffness of the isolationdevices. This strategy is particularly effective forshort stiff buildings (i.e., with a fundamental modeless than 1 sec). For these buildings, it is feasiblewith the isolation devices to develop a new funda-

6-4


mental mode with a period of about 2 sec. Formost sites (e.g., those with a predominant siteperiod less than 1 sec), the new fundamental modeperiod will be beyond the portion of the responsespectrum that is subject to dynamic amplificationand the response of the structures will be greatlyreduced. The concept of base isolation is not new;for many years it has been used to reduce thevibration of equipment and machinery withsprings, resilient mountings, and shock absorbers.Similarly, bridges and other simple structureshave been isolated to reduce vibration and noise,and in some instances, to reduce the seismicexcitation. The application to complex structures,such as buildings, has been made possible inrecent years due to greatly improved computa-tional capability (e.g., high speed, large capacity,digital computers) and development and marketingof the isolation assemblies. A typical installationconsists in large pads of natural or syntheticrubber layers bounded to steel plates in a sand-wich assembly. The isolator assembly, as well asall connecting elements and building services,must be capable of resisting the design spectraldisplacement corresponding to the new fundamen-tal mode (a recent California installation has baseisolation assemblies that can deflect elastically upto 18 inches). Some base isolation assemblies mayhave a lead core or other devices to increasedamping and thus decrease the response at theisolator. Because of the uncertainties associatedwith ground motion predictions, most seismic baseisolators are designed with fail-safe provisions toarrest the motion of the building prior to develop-ment of instability due to excessive displacementof the isolator. Base isolation can be an effectivestrategy to reduce the seismic response of build-ings provided careful consideration is given to theamplitude and frequency content of the expectedground motion; the design of the connecting ser-vices to accommodate the expected displacements;and provision of fail-safe mechanisms as describedabove. The ability of base isolation to reduceseismic response is even more attractive in appli-cation to existing buildings with inadequate seis-mic resistance. However, in addition to the consid-erations described above, installation of baseisolation in an existing building entails accuratedetermination of the magnitude and location of thevertical loads; a rigid diaphragm above the isola-tors to collect and distribute the lateral loads; andcareful underpinning and jacking of the existingstructure in order to effect a systemic transfer ofthe existing structure in order to effect a system-atic transfer of the existing foundation loads to thebase isolation device. Base isolation has beeninvestigated for a number of existing structures

(base isolation for an historic structure in SaltLake City is currently under construction), andthere are provisions to establish construction feasi-bility or cost-effectiveness of base isolation forseismic upgrading.

(b) Energy dissipation. An effective meansof providing a substantial level of damping isthrough hysteretic energy dissipation. Some struc-tures (e.g., properly designed ductile steel andconcrete frames) exhibit additional damping andreduced dynamic response as a result of the lim-ited yielding of structural steel or concrete rein-forcement. Mechanical devices, designed to in-crease structural damping, have been developedusing mild steel in flexure or torsion and thedeformation of lead by extrusion or shear. Viscoe-lastic materials in shear have been used success-fully to control wind vibration in tall buildingsand similar installation have been proposed forreducing the seismic response of buildings. Fric-tion is another source of energy dissipation thatcan be used to reduce dynamic response and limitdeflections. However, frictional resistance is diffi-cult to quantify and its reliability may be ques-tionable. Hydraulic damping has been successfullyused on machinery and bridge structures, butthere are no known applications used to modifybuilding response. The use of structural dampersto reduce the seismic response of existing build-ings may be feasible and cost-effective. The instal-lation of viscoelastic structural dampers as analternative upgrading concept for design exampleF-3 has been developed in a recent technicalarticle (see biblio Scholl, R.E.).

b. Selection of strengthening technique.(1) GeneraL The selection of an appropriate

strengthening technique for the upgrading of anexisting building that does not comply with theacceptance criteria of chapter 5 will depend uponthe type of structural systems in the existingbuilding, the nature of the deficiency, and theconsiderations given in subparagraph a above. Insome cases, the selection may be influenced byother than structural considerations. For example,a requirement that the building be kept opera-tional, with minimal interference to the functionsthat it provides during the structural modifica-tions, may dictate that the modifications be re-stricted to the periphery of the building with asmuch work as possible accomplished on the exte-rior of the buildings. On the other hand, it may bepossible temporarily to relocate the function andoccupants of an existing building that is to beupgraded. This, of course, provides more latitudein the selection of appropriate and cost effectivestrengthening techniques. In many cases, seismicupgrading is accomplished concurrently with func-

6-5


tional alterations, renovation, and/or energy retro-fits. In these cases, the selected structural modifi-cation scheme should be the one that best suits therequirements of all the proposed alterations.

(2) Examples.(a) An existing unreinforced masonry build-

ing with inadequate shear capacity in walls hasreinforced concrete floor and roof diaphragms thatare adequate in shear capacity, but do not haveadequate chord strength for the flexural action ofthe diaphragms. A rigid system of new reinforcedconcrete shear walls or steel braced frames will berequired to provide the additional strength andrigidity to protect the masonry walls. Because achord has to be developed for the existing dia-phragms, it may be advantageous to considerstrengthening the masonry wall with a new rein-forced concrete wall on the inside of the masonrywalls as described in paragraph 6-4b(4). This willfacilitate anchorage of the masonry walls for out-of-plane forces, development of a new diaphragmchord, and shear transfer from the existing dia-phragms. A portion of the masonry wall may beremoved to reduce the loads on the existing foun-dations. If the full thickness masonry walls canspan vertically for the seismic out-of-plane forces,consideration can be given to providing the newconcrete walls in selected locations while minimiz-ing the eccentricity between the center of massand the new center of rigidity. The diaphragmchords must be continuous to resist the horizontalflexural stresses in the diaphragms and to providethe necessary support to the masonry walls.

(b) A two-story steel frame building has 7frames in the transverse direction and 3 frames inthe longitudinal direction. Three of the 7 frames inthe transverse direction and 2 of 3 frames in thelongitudinal direction are moment frames. Thefloor and roof diaphragms consist of steel deckingwithout concrete fill. The existing frames anddiaphragms are adequate for the acceptance crite-ria in the longitudinal direction. The 3 existingtransverse frames do not meet the acceptancecriteria for drift and the diaphragms do not haveadequate shear capacity in the transverse direc-tion for the three bays between the momentframes, but they would be adequate for only twobays. There are a wide range of possible solutionsto this example: the diaphragms could bestrengthened by adding a concrete fill (para64b(7Xc); the existing transverse moment framescould be strengthened (paras 64b(lXa) and (b);some of the intermediate transverse frames couldbe made moment-resisting (para 64b(lXd)); or newreinforced concrete shear walls or steel bracingcould be added to reduce the drift. It should benoted that modifying the intermediate frames for

moment resistance may not be feasible because ofinterferences with the steel decking. Adding con-crete fill to strengthen the steel decking willrequire removal and replacement of the secondfloor and the roof. New concrete shear walls willrequire new foundations. Considerable cost savingcan be achieved by eliminating or minimizing thework on the roof, floor, and foundations. Verticalsteel bracing becomes a logical solution. If thebracing is installed at the end transverse framesand at every other frame in between, the existingdiaphragm will only have to span two bays andwill not need to be strengthened. The bracing willbe effective in reducing drift, but the resultingshorter period will probably increase the seismicdemand forces that now will be resisted primarilyby bracing. However, with 4 lines of bracing, theforces are well distributed and the additionalfoundation loads (shear and overturning forces)may not be difficult to accommodate with theexisting foundations.

(c) An existing two-story office building thatperforms an essential function must be seismicallyupgraded. The building has an identified defi-ciency in the transverse direction in which thelateral forces are resisted by nonductile concreteframes. The detailed structural analysis indicatesthat additional lateral load resistance is requiredand also that building deformation must be lim-ited so that allowable drift and inelastic demandratios for the nonductile frames are not exceeded.The structural modification must be accomplishedwith minimal interference to the functions andoccupants in the building. The above restrictionsdictate that the optimum solution would be onethat provides significant rigidity and can be imple-mented from the exterior of the building. If thefloor and roof diaphragms comply with the require-ments of chapter 5 of the BDM, an appropriatescheme for the upgrading would be to providebracing or shear walls at each end of the building.A potential problem with this scheme might beinadequate resistance to the overturning forces atthe foundation level. Possible solutions to theoverturning problem would be larger footings;drilled piers to provide tension tie-down; buttressesin the plane of the end walls to increase theresisting lever arm for the overturning moments;or internal shear walls to reduce the lateral forceson the end walls. Prefabricated steel shear walls(para 6-4d(2X)) can be used to minimize the timeand area of disruption in an existing building.

(d) An existing three-story unreinforced ma-sonry building is to be seismically upgraded be-cause of the historical significance of its externalarchitecture. The building will be used as anadministration building after the seismic upgrad-

6-6


ing. The roof and floor systems are timber postand beam construction and the timber flooring isinadequate for diaphragm action or to anchor thewalls. Retention of the timber framing will requireinstallation of a sprinkler system. In this buildingconsideration should be given to reconstruction ofthe second floor and roof systems in reinforcedconcrete. The existing exterior walls may needtemporary shoring while a new reinforced concretewall is constructed at the interior face of theexisting walls (para 64)). The new walls andfloor and roof framing will provide the lateralforce systems and will provide the necessary sup-port to the existing exterior walls.

c. Strengthening options for structural systems.Paragraph 6-4 describes various generic strength-ening techniques for structural elements. The pre-ceding subparagraph provides two representativeexamples for the selection of appropriate strength-ening techniques that are compatible with theexisting structural system and will correct thedeficiencies identified in the detailed structuralanalysis. Tables 6-1 to 6-8 provide a listing ofvarious strengthening options that may be consid-ered for seismic upgrading. This listing should notbe considered to be complete or exclusive and theengineer is encouraged to use his initiative in thedevelopment of the three required alternative up-grading concepts from the options described in thetables or by innovative variation of those options.

d Reanalysis. Each alternative upgrading con-cept will be evaluated for compliance with theacceptance criteria in chapter 5. Unless the effectsof the structural modifications on the mass, stiff-ness, and load distribution in the building areobviously negligible, a reanalysis of each conceptwill be required. The reanalysis will be similar tothe detailed structural analysis but with the re-vised structural model resulting from the upgrad-ing modifications. In most cases the effect ofstrengthening and/or stiffening of an existingbuilding will reduce the modal periods of vibrationand increase the spectral demand on the building.One or more analysis iterations may be requiredto reconcile the modified capacity of the buildingwith the seismic demand.

e. Damage control check. After each alternativeupgrading concept has been checked for compli-ance with the acceptance criteria for EQ-II forces,it will also be checked as follows for essentiallyelastic response to EQ-I forces:

(1) EQ-I analysis. Perform an EQ-I analysisin accordance with paragraph 4-3 of the SDG. Theacceptance criteria prescribed in paragraph SDG4-3e(1) will be modified as follows:

(a) Ductile framing systems. The 25 percenttolerance allowed in excess of the flexural elastic

capacity for a limited number of elements may beincreased to 30 percent.

(b) Other framing systems. The 10 percenttolerance allowed in excess of the flexural elasticcapacity may be increased to 15 percent.

(c) Box systems. These systems may notexceed the elastic capacity requirements of theSDG.

(2) Alternatives to EQ-I analysis. When theEQ-fl reanalysis prescribed in paragraph d abovehas been performed by Method 2, compliance withEQ-I requirements may be made by comparingthe elastic capacities, calculated for the EQ-IIreanalysis, with the EQ-I spectral requirements.When the EQ-II reanalysis has performed byMethod 1 (conventional elastic analysis), the fol-lowing procedures may be used:

(a) Compare the response spectrum for theEQ-I elastic response to that for EQ-II post-yieldresponse. Determine the spectral acceleration ordi-nate, S, at the building's fundamental period onthe EQ-I spectrum and the corresponding ordi-nate, Son, on the EQ-II spectrum.

(b) Calculate the ratio, R =(c) Examine a representative sample of in-

elastic demand ratios (IDR) at each level of thebuilding.

(d) Determine what portion of each IDR isattributed to seismic response as opposed to re-sponse to the vertical gravity loads (e.g., for shearwalls with an IDR of 1.50, the entire amount maybe due to seismic loads where a concrete or steelframe column with the same IDR may have 0.60due to gravity loads and 0.90 due to seismic loads).

(e) Multiply the seismic portion of the IDRby the ratio, R, previously calculated and add thisto the gravity load portion of the IDR (e.g., for agiven building, if R = 0.40, the same shear wallwith an IDR of 1.50 for EQ-II would have an IDRof 0.60 (i.e., 0.40 x 1.50) for EQ-I while the aboveframe column would have an E)R of 0.96 (i.e., 0.60+ 0.40 x 0.90)).

() Unless adjustments are made for differ-ences in EQ-I and EQ-fl gravity load factors,none of the tolerances permitted for exceeding theflexural elastic capacity in paragraph 4-3e(1) ofthe SDG and paragraph (1) above will apply.

f Comparative cost estimates. After it has beenconfirmed that each alternative concept is in com-pliance with the acceptance criteria, comparativecost estimates will be prepared to provide a basisfor the selection of the recommended concept.Since the primary purpose of these estimates is todifferentiate the relative costs of the concepts, acomplete cost estimate is not required at thispoint. Only those principal items of cost that varyamong the concepts need to be recognized. For

6-7

0a

Table 6-1. Strengthening option. for unreinforced concrete or masonry building. (Sheet I of 2)

Structutal smenSt

S. Shear walls

b. Counectins beam.

C. Concrete floor orroof diaphragms

d. Fimber floor oftoof diaphragms

De ficiaecy

(1) Inadequate shearcapacity

(1) Inadequate shear ortlerurol capacity


(2) Inadequate chardcapacity

(3) Inadequate wailanchorage


(2) Inadequate chordcapacity

(3) Inadequate wailanchorage

Btrsgtb-aLo Toehnlque

(a) Add reinforced concreteto eterior face

Cb) Add reinforced concreteto interior fce

(c) Remove ad replace withreinforced concrete

() fill-in openings

(b) Remove and replace withreinforced concrete

Ca) Overlay with new rein-forced cncrete slab

(a) Add nov reinforced con-crete chord

(a) Provid, drilled-in wallanebors to ew construction

(a) Overlay with plywood

(a) Add nw continuous steelangle

(a) Provide drilled-in wallanchors to new construction

ef erases

Pare. 6-4b(4)

Pare. 6-4b(4)

Para. 6-Ac

Por.. 6-4b(3)Ca)

Pors. 6-4b(3)(a)

Pora. 6-4b?)(bi

Para. 6-4b(?)(b)

Pars. 6-4b(4)

Perr. 6-4b(7)(a)

Pore. 6-4b(7)(a)

Pars. 6-4b(7)(e)

z

4pplicable flur >

*lsuro 6-7p

figure 6-10 T

figur 6-22

figur 69

C*

figure 6-1

flgut 6-16 :

Pig. 6-10. 6-16. ,6-17 -

Figo. 6-7, 6-8, 6-10, 6-16, 6-17 t

pigurce 6-14.

figure 6-14

figure 6-14

Shot I of 2

i

41..Om

.4

-a

0.a.

0C4

1

MD.0

aso

4.1 4*tU U_ _-4 -4

m -

.Y W

I . 4..S A

4. 4U S.

4,4

a

4.4XfS

-C

.

S.a-

a-3,

.S

-C

I

A

-4 44'

a.

S LII ,C S

_ * I -a

c 0 * i *_ .~~ -4 4~~- 1-4 0 b do~

i.4 .4. v

*. .| I 'L

F l _*. -ma -_ _.


example, if diagonal bracing and eccentric bracingare considered as alternate concepts to be installedin the same number of bays and both conceptsrequired the same strengthening of floor and roofdiaphragms and foundations, only the differentialcosts of the two bracing systems need to beidentified.

g. Selection of recommended concept. The opti-mum concept will be the one that meets theacceptance criteria and best satisfies the generalconsiderations of subparagraph a at a reasonablecost. This may not necessarily be the least expen-sive concept if justification can be provided forgreater reliability, improved structural perfor-mance, functional advantages, or reduced mainte-nance of a better and more cost effective system.

6-4. Strengthening techniquesTechniques for strengthening or upgrading exist-ing buildings will vary according to the natureand extent of the deficiency, the configuration ofthe structural system, and the structural materialsof which it is comprised. It is not practicablewithin the scope of this manual to deal with everypossible variation of all conditions. This paragraphwill provide guidelines for the seismic upgrading-of typical structural members or systems andguidance for structural engineers to utilize judg-ment and ingenuity to deal with specific situa-tions. The strengthening or seismic upgrading ofthe building will generally fall into one or more ofthe following categories: rehabilitation of existingstructural members; modification of existing struc-tural members; replacement of existing deficientstructural members; or the addition of new struc-tural members or elements (i.e., shear walls,braced frames, etc.).

a. Rehabilitation of existing structural members.Seismic upgrading of existing buildings bystrengthening or replacement of existing struc-tural members and/or the addition of new struc-tural members may also require rehabilitation torestore the initial capacity of existing structuralmembers that have been subjected to damage ordeterioration. Representative examples of feasiblerehabilitation for typical structural members aredescribed in appendix E. General deterioration ofmaterials, such as corrosion of structural steelmembers or concrete reinforcement, or weatheringof concrete brick or mortar, may not be readilyrepaired and such materials will be assigned acapacity reduction factor as indicated in appendixE.

b. Modification/strengthening of existing struc-tural members. In some cases, the modificationand/or strengthening of existing structural mem-bers could be the most cost effective method for

D-

I 04, 44.

*0..a.

I44,

..3M

a-.

a U'E a_ _

'W4 ,4

- 4

4. a

8

* T

,. 0; S4.

* 0

0.Ia0

Structural lmet

*. hese wells

b. Connecting boem

C. Concrete floorroof dephrc s

(1) I

Table 6-2. Strengthening options for reinforced concrete or masonry shear wall buildings. (Sheet I of 2)

Deficiency StrengtheaIg Technique Reference

Inadequate hear (a) Add reinforced concrete Para. 6-4b(3)(a)eepacity to exterior face

(b) Add reinforced concrete Per. 6-4b(3)(e)to Interior fecs

(c) fill-i opening. Pare. 6-4bC3)()

(d) Add m nterior concrete Pore. 6-4dC2)(b)cheer wells

Ce) Add new interior steel Pero. 6-4d(2)(b)ehear well.

(f) Add nw exterior steel or Pare. 6-4d(s)concrete buttresses

(a) Romove and replece with Pate. 6-4b(3)(a)new construction & 6-4c

Inadequate ehonr or (C) fill-in openings in Pore. 6-4b(3)(a)tlexural cpacity ehear wll.

(b) leove and replece with Pre. 6-4b(3)(e)reinforced concrete

Inadequate shear (e) Overley with new rein- Pare. 6-4b(7)(b)epecity forced concrete lab

Inadequate chord (e) Add new reinforced con- Pare. 6-4b(7)(b)4pacity crete chord

Inadequate wll (e) Provided drilled-in wll Pers. 6-4b(4)snchorage anchors

Appliceble igure

Figure 6-7

Figure 6-10

Figure 6-9

Figure 6-24

Figure 6-25

Figure 6-28

Figure 6-22

Figure 6-9

Figure 6-9

Figure 6-16

Fig. 6-10. 6-16.6-17

Figs. 6-7. 6-8.6-10. 6-16. 6-17

Sheet I of 2

9

co0%0I0

0

z

In'

n

Ca

4A

0In

U

CCD

0

A

0C1) I

C1) I

(2) 1

(3) 1a

( ( (


0

A

.4.

A.

'0

-4m4

_ _ " f* ;It . f 4 .4

la * * .4 4 .4 - 4

* a 0 SW_ _ _ _ _3

R

'-_

-C

&a

.3

.0a

.t

9

O.

a

-c

EA.0

-a

.S

-..

-

0

a4.

* * U

.0 .0

* a N Df. j A: : : :

.0

lI.

S;a.1

.0

* U

A. 4.

A. A.

* U

44 ~ ~ ~ ~ ~ ~ *4

* _ ' 4 . _

*i - 4 ,. 00.e _

*E 4r|. ' e . 0

_ . . . .-4 ,

the seismic upgrading of an existing building.Typical examples of the structural modification ofexisting structural members, in place, are providedin the following paragraphs. Other cost-effective

' methods will be investigated for each conditionC4 illustrated in figures 6-2 through 6-28.

(1) Structural steel framing.(a) Columns. The capacity of columns is

determined from interaction equations for axialloads and bending, thus the seismic capacity of acolumn can be upgraded, within reasonable limits,by increasing either or both its capacity for axialloads or for moment. The axial load capacity ofsteel columns can be upgraded by welding coverplates on the flanges or by "boxing" the columnwith plates between the tips of the flanges. Typicaldetails are indicated on figure 6-2. These platesmay also serve to increase the moment capacity ofthe columns at the base. Increasing the momentcapacity of existing columns at the beam-columnconnection is usually not feasible because of theinterference of the connecting beams. In somecases, it may be possible to increase the shearcapacity of the column web with doubler plates asindicated in figure 6-2 provided that there isadequate clearance for the necessary welding.

(b) Beams. Strengthening of existing beams,in place, may be required to improve the momentcapacity by an increase in the section modulus, S,or to reduce drift by an increase in the moment ofinertia, I. The section modulus of a beam may beincreased by welding cover plates to the top orbottom flanges. In many cases, it may not befeasible to provide cover plates on the top flangebecause of interference with the floor beams, slabs,or metal decking. (Note that for a bare steel beam,a cover plate on only the lower flange may notsignificantly reduce the stress in the upper flange.)However, if the floor slab or metal decking isadequately detailed for composite action at the endof the beam, it may be economically feasible toincrease the moment capacity by providing coverplates at the lower flanges at each end of the beamas indicated in figure 6-3. The length of the coverplates, in this case, will be determined from thecombined (DL + LL + EQ) demand momentdiagram. The cover plates will be tapered asshown to avoid an abrupt change in section modu-lus beyond the point where the additional sectionmodulus is required. Where frame drift governs, itmay be feasible to increase the moment of inertiaand thus reduce the drift by the addition of a coverplate to the lower flange of existing steel beamsbetween the columns as also indicated in figure6-3. It should be noted that beams with discontin-uous cover plates must be treated as tapered orhaunched sections and will have different carry-

6-11

2 1

,:

cZ

aI.-4

.

* he

CU

.4 a,

04.

_ *-4 _0.0.

-4

v 4.

. S S

E > "

I. .

v '3

i

4.

0

0.

0.

Table 6-3. Strengthening options for reinforced concrete frame buildings.

Structural U met

. rews

b. Concrete Floor orroof diaphragm

C. pread footings

4. File or drilledpiet tootig

Vt Wiciency

Cl) Inadequate lateralload capacity

(1) Inadequate *hearcapacity


(I) Inadequate loadcapacity

(1) Inadequate loadcapacity

Strengthening Technique

(a) Add n aterual teelfraeo

Cb) Add new interior concretebear walls

(e) Add nJU Interior steelshear walle

Cd) Add waw eterior concreteor steel buttressed

(e) Structural ddition() tobuilding

(f) lemoe nd replace withDw construction

(a) Overlay with nw rein-forced concrete lab

(C) Add new reinforced concretechord

(a) Underpin xisting footings

b) Remove and replace withnew footings

(C) Add additional pile orpiers. eove nd r-place meisting caps.

Reference

Pare. 6-4d(l)(a)

Pare. 6-4d(2)(b)

Pars. 6-4d(2)(b)

Pare. 6-4d(S)

Pars. 6-4d(6)

Per. 6-4b(2) 6-4c

Para. 6-4b(7)(b)

Pers. 6-4b(7)(b)

Pars. 6-4b(8)(a)

Pars. 6-4c

Pars. 6-4b(8)(b)

Applicable Figure

Figure 6-23

Figure 6-24

Figure 6-25

Figure 6-28

Figure 6-22

figure 6-16

Figs. 6-16. 6-17

Figure 6-20

Figure 6-22

figure 6-21

-4

I

0

z

*I"

n

"a

10cm'

!A0%

In'

'Aco1

n

(

(

Table 6-4. Strengthening options for steel moment-resisting frame buildings. (Sheet I of 2)

(

Structural Elo ent

a. Steel frames

Dof ic icy

(1) Inadequate lateralload capacity

Strengtbening Technique

(a) Strengtbn existingcolumn#

(b) Strengtbon existing beas

(e) Modify meisting simplebea" connections

(d) Add diagonal bracing

(e) Add eccenttl bracing

CM) Add now interior orexterior concrete hearwalls

Reference

Pare. 6-b(l)(a)

Pere.

Para.

paro.

Pare.

Pere.

6-4b(l)(b)

6-4b(l) (d)

6-Ad(3)

6-Ad(3)

6-4d(2) (a)& (b)

Applicable Figure

Figure 6-2

figure 6-3

Figure 6-5

Sie. to Fi. 6-4

Figure 6-26

Figure 6-24

b. Concrete floo orroof diaphragmo

(1) Inodequate heercapacity

(g) Structural dditiona)to building

(a) Overlay with n rein-forced concrete rlab

(b) Add ee horizontal teelbracing

(C) Add heer etude

(e) Modify existing *pendrelconnections

Parm. 6-4d(6)

Pare. 6-Ab(7)(b)

Pare. 6-4d(4)

Paro. 6-Ab(?)(b)

Pare. 6-4b(l)(d)

Figs. 6-16. 6-18

figure 6-2t

Sim. to Fig. 6-19

Figure 6-6

(2) Inaeuate beartranifer

(3) Isedsquate diaphragmcbord

0%0

z

-n

laIl

,

.CD0m.I

M*VI

0

Sheet I of 2

0h

(I

0d

structutl Uleat

C. Steel deck flooror roof diaphragas

d. Timbor floor orroof diaphragms

e. Spread footings

f. Pile or drilledpier footings

Tablk 6-4. Strengthening options for steel moment-reaisting frame buildings. (Sheet 2 of 2)

Doflc"Loc7 Strengtbening echnique Kefereace

(3) Inadequate shar (a) Additional waldinU of Pete. 64b(7) ()capacity deck to beus

(b) Add concrete fill *ed Ptr. 6-4b(7)(e)shoar etude

(c) Add nw brisontal stol Pre. -4d(4)bracing

(1) Inadequate shear (a) Overlay with plywood Pore. 6-4b(?)(C)capacity

(b) Add am borlsontel to l Pars. -4J4)bracing

(2) Idequate hear (a) belt timber decking to Pare. 6-4bC)(Ca)treasfer steel frame

Cb) Bolt timber joists or Pars. -4b(C)(0)blocking to stel frame

Cl) Inadequate load (s) Underpia xisting footings Pare. 6-4b($) Ca)capacity

(b) Rewo ad replace with Pore. -4cDew footings

(1) Inadequate load (a) Add o additional piles Pare. 6-Ab()(b)capacity or pierc. Remove and re-place misting cape.

Applicable igure

BDX (rigs. 5-19 5-20)

figure 6-19

Pigure 6-27

Pigure 6-14

Figure 6-21

Figure 6-15

Pigure 6-15

Figure 6-20

Figure 6-22

Figure 6-21

-4

40

':0

In

4A

*I

0

a

*0

n

Shoet 2 of 2

(,

TM 5-809-10-2/NAVFAC P-35S.2/AFM 88-3, Chop 13, Soc B

over factors for moment distribution than pris-matic members. This may tend to increase thebeam moments over the values for the unmodifiedbeams and should be carefully checked to avoidundesirable overstress at critical sections of thebeam. The capacity of steel beams in rigid framesmay, in some cases, be governed by lateral stabil-ity considerations. Although the upper flange maybe supported for positive moments by the floor orroof system, the lower flange must be checked forcompression stability in regions of negative mo-ments in accordance with section 1.6.1.4 of theAISC Specification. Although properly designedsecondary floor beam connections may provideadequate lateral support for those frame beamssupporting these secondary beams, beams inframes that are parallel to the secondary beamsmay need lateral support for the lower flanges incompression due to negative moments. The neces-sary lateral support may be provided by diagonalbraces to the floor system.

(c) Bracing. Strengthening of existing steelbracing, in place, is a viable alternative, providedthat the connections, foundations, and other mem-bers of the bracing systems are adequate or canalso be strengthened to provide the necessaryadditional capacity. Strengthening of beams andcolumns in bracing systems can be accomplishedas discussed in paragraphs (a) and () above, andstrengthening of bracing members that are de-signed to act only in tension can be accomplishedby simply increasing the cross-sectional area of thebrace. In strengthening bracing that will act inboth tension and compression, it is desirable tostrenghten the bracing in a manner that willimprove the slenderness ratio, I/r, as well asincrease the cross-sectional area. For existing sin-gle angle bracing, this may be done by adding anadditional angle, back to back, to provide a doubleangle bracing system. For existing double anglebracing, an additional pair of angles may be addedto provide a "starred" section. Typical strengthen-ing details for bracing are shown in figure 64.

(d) Connections. Development of a feasiblescheme for strengthening the existing connectionsmay be the deciding factor as to whether it ispracticable to strengthen existing deficient steelframing. Figure 6-5 indicates how an existingsimple beam connection can be modified to resistmoment. Spandrel beams in perimeter frames aresometimes required to provide the necessary ten-sion or compression chords for floor or roof dia-phragms. If these existing beams are framed to thecolumns with only simple connections, the flexibil-ity of the connection in tension may result inexcessive cracking of the diaphragm. Figure 6-6indicates how an existing simple beam connection

in a spandrel beam can be modified to providepositive chord action for diaphragm. Columns alsocan be modified to provide increased momentcapacity at their base, but the capacity of the basedetail needs to be investigated for resistance to theadditional moment and horizontal shear resultingfrom these modifications. Assuming that the foun-dation is adequate (see paragraphs 6-4b(4) or6-4c(4) for modification or replacement of existingfootings), the maximum allowable bearing stressunder the base plate or the tensile stresses in theanchor bolts may govern the moment capacity atthe column base. These stresses are governed bythe size of the base plate and the number andconfiguration of the anchor bolts. While it may bepossible to strengthen the column and to stiffenthe base plate against local bending, it is usuallynot practicable to increase the size of the baseplate or the number of anchor bolts withoutremoval and replacement of the base plate. Thehorizontal column shears may be transferred tothe column footing by shear lugs between the baseplate and the footing, and/or shear in the anchorbolts, and to the ground by passive pressureagainst the side of the footing. If the column baseconnection is embedded in a monolithic concreteslab, the slab may be considered for distribution ofthe shear to the ground by means of any addi-tional existing footings that are connected to theslab.

(2) Concrete frames. Strengthening of existingconcrete frames is not considered practicable be-cause of the difficulty associated with providingthe necessary confinement and shear reinforce-ment in the beams, columns, and the beam-columnpanel zones. When deficiencies are identified inthese frames, the forces and displacements resistedby these frames can be reduced to acceptablelimits by the addition of new structural members(e.g., new frames, shear walls, or bracing) asindicated in paragraph 64d.

(3) Reinforced concrete or masonry walls orpiers.

(a) Walls with openings. Existing reinforcedconcrete or masonry walls with openings mayexhibit deficiencies (e.g., excessive shear stresses)in the piers between the openings and/or in theconnecting beams between the piers formed by theopenings.

1. If the deficiency is in both the piersand the connecting beams, the wall may bestrengthened by the addition of reinforced concreteon one or both sides of the existing wall asindicated in figure 6-7. Shallow, highly stressedconnecting beams may have to be replaced withproperly reinforced concrete as part of the addi-tional wall section. The new concrete may be

6-15

0.-A

0.

Table 6-5. Strengthening opotions for steel braced frame building. (Sheet I of 2)

Structural *1ewest

a. Stool brecing

b. Concrete floor orroof diaphregms

c. Steel deck flooror roof diaphragms

OaficlDcy

(1) Inadequate axialload capacity


(2) Inadequate wheartransfer

(3) Inadequate diaphrogchord

C1) Inadequate shearcapacity

Strengthening Technique

(a) Increase effective areaof braces

(b) Remove and repl ee withlarger bracing

(c) Add additional brace

(d) Add exterior or interiorconcrete shear well.

(a) Structural addition()to building

(a) Ovetlay with new reitforced concrete slab

(b) Add new horiontal steelbracing

(a) Add shear etude

(a) Modify existing spandrelconnectione

(a) Additional welding of deckto beane

(b) Add concrete fill andshear etude

(c) Add new borisontel steelbracing

Nefereoce

Per. 6-4b(l)(c)

Pare. 6-4c

Pare. 6-4d(3)

Pare. -44(2)(s)and (b)

Pore. 6-4d(6)

Paro. 6-4b(?)(b)

Pore. 6-4d(4)

Pore. 6-4b(7)(b)

Pars. 6-4b(1)(d)

Pare. 6-4b(7)(c)

Pars. 6-4b(7)(c)

Pars. 6-4d(4)

Applicable Figure

Figure 6-4

figure 6-24

figs. 6-16. 6-18

Figure 6-21

Sin. to Figure 6-19

Figure 6-6

5DM (Figs. 5-19. 5-20)

Figure 6-19

Figure 6-27

9-4

IaC0

Ia)0

1

z

n

-

2,,-I

00

co~

alaw

Bhast I o 2

(

( ( (

Table 6-5. Strengthening options for steel braced frame buildings. (Sheet 2 of 2)

structural nlment

d. imber floor orroof diaphragm.

Detileency

(1) Inedequate heotcapacity

(2) 2uadequate weattransfer

Strengtbenig Techdique


(b) Add sm. borizontel st elbracing

(a) Polt timber dcking to steelfrees

(b) olt timber joist orblocking to teel fre o

(a) Underpin eisting footings

(b) Neee and replace withnew footings

(a) Add dditional piles orpiers. Remme nd replaceexisting Cape.

Nefereoeo

Pare. 6-4b(7) (a)

pera. 6-Ad(A)

Fere. 6-4b(7)(a)

ter. 6-4b(7)(u)

Pare. 6-4b(8)(e)

Appliceble Figure

figure 6-14

Figure 6-27

Figure 6-19

Figur 6-15

Figure 6-20

figure 6-22

Figure 6-21

o. Spread footings

f. ile or drilledpier footing.


(1) Inedequate loadcapacity

Pare.

Pore.

6-Ac

6-Ab(8) (b)

04

0'0

o

z

0

1,

.5Z

I

CS)

A

a

,

I'P

Sheet 2 of 2

-a

-0

Table 6-6. Strengthening options for heavy timber frame buildings.

Structural Memot

o. Pets "d bea"

b. Tiber floor orroof diapbragm

c. Spread footings

d. Pile r drilledpier

Def Icleaec


(1) Inadequate heercapacity

(2) Inadequate heartranfer




treegtbeciag Technique

(a) Add diagonal bracing

(b) Add knee bracing


(a) Provide blocking fornailing to diaphraoand frame members

(a) Provide continuous teelmembere for chord ction

(b) Provide continuous timbermembers for chord action

(a) Underpin *risting footing.

(b) Remove and replace withnew footings

(a) Add additional pile orpiers. Remove and replace

$itiag Cpe.

Reference

Pare. 6-4b(5)(a)

Pare. 6-4b(s) ()

Para. 6-4b(7)(s)

Pore. 6-4b(7)(s)

Applicable figure

figure 6-11

figure 6-12

Figure 6-14

Figure 6-11

figure 6-14

ID (figure 5-33)

Figure 6-20

figure 6-22

figure 6-21

9-4

010*0

z

n

COIV

I

0

(-)

A

a

C.)

PIk4w.

Pare.

Pare.

Pars.

Pars.

Pore.

6-4b(?) (a)

6-4b(7) (a)

6-4b(8) (a)

6-4c

6-4b(8) (b)

K ( (

( ( (

Table 6-7. Strengthening options for uood stud framed buildings.

Itructurtl lameont

A. ood stud *ll

b. Timber floo orroot diaphragms

c. Spread footings

d. Pile ot drilledpier footings

Def iency


(2)

(1)

(2)

O)

(1)

Inadequate tie-downcapacity

Inadequate hearcapacity

Inadequate *heertransfer

Inadequate dragstruts

Inadequate loadcapacity

8trentbaning Technique

(a) Add plywood heathing

(b) Add let-lin bracing

(a) Add new steel tie-downstraps

(a) Overley with plywood

(a) Provide blocking *nd"ailing. s n e**osry

(a) Provide new drag struts

(a) Underpin evioting footings

b) Remoe and rploce with newfootings

(a) Add additional piles or piers.Remove snd replace eRistingCap*.

Reference

Fare. 6-4b(5)(b)

Pars. 6-bCS)(b)

Pnra. 6-4b(5)(b)

Pars. 6-4b7)(o)

Para. 6-4b7)(a)

Pars. 6-Ab(7)(a)

Pars. 6-4b(B)(a)

Pare. 6-4c

Para. 6-4b(8)(a)

Applicable Figure

3DM (Figs. 5-32. 5-34.6-15. Tble 5-6)

figure 6-13

3DM (Figure 6-16)

Figure 6-14

DH (igs. 5-33. 6-15)

3DM (igure 5-34)

Figure 6-20

figure 6-22

Figure 6-21

-4

U,

I0

0

z

91

!A

I0

r,

1

10

-A

$0

VIIA

M


-a'0

0.

0

Table 6-8. Strengthening options for steel stud framed buildings.

-4

In

0

o

0

I

z

nC'IN

In

co

nU.aC'INSto

Structural lement

*. teel studs

b. Steal deck roof orfloor diaphragms

c. Spread footings

d. ile or drilledpier footings

Det iescy

(1) Iadequate shoarcapacity


(2) Inadequate sheartransfer

(3) inadequate chordcapacity

(1) Inadequate load


Strngtbeoing Technique

(a) Add am steal straps

(a) Provide additional welding

(b) Provide concrete till ndshear tude

(a) Provide new steel embersad welding

(a) Provide nw steel membersand welding

(a) Underpin xisting footingscapacity

(b) Repave and replace with newfootings

(a) Add dditional piles orpire Remove and replaceexisting caps.

Reference

Pare. 6-4e(6)

Pars. 6-4b(7)(c)

Pars. 6-4b(?)(c)

Pars. 6-4b(7)(c)

Pars. 6-4b(C) c)

Pars. 6-4b(8)(a)

Pare. 6-4c

Para. 6-4b(S)(s)

Applicable Figure

DDH (figure 6-17)

3DH (Figs. 5-19& 5-20)

Figure 6-19

BDH (Figure 6-17b)

3DH (igure 6-17b)

figure 6-20

Figure 6-22

Figure 6-21

(

TM 5-809-10-2/NAVFAC P-3S5.2IAFM 88-3, Chop 13, Sec B

colan

Existing columl

I If

,Existingbeams

New cover plate.each side

Section a-a

plate, If eq'd

Cover plateseach side

bF -- ib

Existing column

*Weld to be designed to resist verticalshearing stresses due to column bendingments.

Section b-b

Figure 6-2. Strengthening of existing columns

formed and poured in place or may be placed bythe pneumatic method. Paint or other finish on theexisting concrete surfaces will be removed and theexisting concrete lightly sandblasted to improvethe bond of the new concrete.

2. If the identified deficiency exists onlyin the connecting beams, consideration will begiven to acceptance of some minor damage in theform of cracking and/or spalling by repeating thestructural evaluation with the deficient beamsmodeled as pin-ended links between the piers. Ifthis condition is unacceptable, the beams will beremoved and replaced with properly designed rein-

forced concrete as indicated in figure 6-8. Analternative to the above procedures is to fill inselected openings with reinforced concrete as indi-cated in figure 6-9. The number and location ofthe openings to be filled in with concrete willdepend on functional and architectural as well asstructural consideration. If none of the abovealternatives are feasible or adequate to ensure theproper performance of the wall, the wall willeither be removed and replaced with a new wallthat complies with the criteria in chapter 5 or willbe supplemented by the addition of new structuralelements, as described in paragraph 64d, that

6-21

TM 5-809-10-2/NAVFAC P-355.21AFM 88-3, Chop 13, Sec B

Ing beam

plate

Section *-a

Existing concrete slab

at [a

Detail I

Cover Plates to Increase MomentCapacity at Ends of Beams Designedfor Composite Action with Slab

Ly- Cover plate

H -= == -==-

Existing beam

-bSection b-b

i

7 - . ' 1 0

Existing steel decking

I

,_- _ bmb Existing beam b

L- - - Cover plate

Deta1 2

Cover Plate to Increase Moment ofInertia of Beams Not Designed forComposite Action with Decking

Figure 6-3. Strengthening of existing beams

6-22

TM 5-809-10-2/NAVFAC P-355.21AFM 88-3, Chap 13, Sec B

Ex s t.vangle

Spacer. new angleas rq 'd

Detail Section a-a Oetaf2

Upgrading of Single Angle Bracingto Double Angle Bracing

Elevat ion

Existing Sngle Angle Oracing

Figure 6-4. Strengthening of exieting bracing

will reduce the forces on the existing wall toacceptable limits.

(b) Walls without openings. Existing rein-forced concrete walls or piers without openings canbe strengthened by the addition of reinforcedconcrete on one or both sides as described abovefor walls with openings and as indicated in figure

6-7.(4) Unreinforced concrete or masonry walls or

piers. Unreinforced concrete or masonry walls orpiers that do not comply with the acceptancecriteria prescribed in chapter 5 will be strength-ened or will have the seismic demand forces thatthey are to resist reduced by the addition of new

6-23

TM 5-809-10-2INAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

fl - 1) - Existfl ~~~~angle

Existing colunw/t

_1 t6 _L Detail rExisting Simple Beam Connection

New web doublerplate, f req'd

Section -a

New mment plate,top and bottom

Detail 2

Modified Connection

Figure 6-5. Modification of an existing simple beam connection to a moment connection

6-24


Existing floor beam

Existing colun.

Detail I

Existing Connection

Shore spandrel beam, asnecessary, weld conhectionangle on one side for sheartransfer. Remove oppositeangle and Install steelplate for chord forces.

Detail 2

Hodified Connection

Steel plate, as requiredfor chord forces

Section&* Section b-b

Figure 6-6. Modification of existing steel framing for diaphragm chord forces

6-25

TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chap 13, Sec.B

4u si n.

New relnf. concrete,cast-in-place orpneumatically placed- - C

Wall anchors. epoxy grouted.,In drilled holes. Not toexceed 3'-0 ctrs. a. way

Figure 6-7. Strengthening of existing r

structural elements as described in paragraph6-6d. The strengthening procedure can be similarto that indicated in figure 6-7 for reinforcedconcrete or masonry. For unreinforced brick ma-sonry walls consisting of four or more wythes ofbricks (16 to 18 inches) in thickness, it may beadvantageous to remove two or more wythes priorto the addition of the reinforced concrete section asindicated in figure 6-10. This procedure has theadvantage of reducing the seismic mass as well asreducing the additional loads on the foundation.For perimeter walls, this procedure is most easilyaccomplished on the exterior face of the existingwall; however, if the building has historical signif-icance or if the exterior face must be preserved,the procedure can be accomplished on the interiorface. Strengthening the interior face of the exist-ing wall will introduce complication because ofslabs, beams, or other structural elements framinginto the wall that may require temporary shoring,but it will facilitate anchorage of the wall andprovide chords for the floor or roof diaphragms asindicated in figure 6-10.

(5) Timber construction(a) Heavy timber constructionL The seismic

capacity of existing heavy timber construction maybe upgraded by the use of diagonal bracing orknee braces. The diagonal braces may be eithertimber or steel and are designed for both tensionand compression forces. Figure 6-11 indicates typi-

6-26

reinfs

Exist. reinf. concreteA.-or rinf. masonry wall

or pier

Clean and roughen exist.wall surface by sandblasting

red concrete or masonry walls or piers

cal details for timber bracing. Knee bracing ofexisting timber framing may be adequate formoderate seismic forces that can be resisted by theresulting knee braced frame with the columnsassumed to be pin-ended. The resulting horizontalshear at the base of the columns must be investi-gated to determine the need for additional connec-tions to transfer the shear to the floor diaphragmor foundation as indicated in figure 6-12.

(b) Wood stud wall Existing wood studwalls in one- and two-story residential or similarconstruction can be upgraded with 1 x 6 or 2 x 6let-in bracing as indicated in figure 6-13. Thecapacity of this bracing will generally be governedby the effective number of nails that have beendriven with allowable spacing and end and edgedistances. For heavier lateral loads, plywoodsheathing of existing stud walls is an effectiveprocedure for providing the necessary resistance.Figure 6-15 of the BDM provides allowable shearvalues for plywood shear walls. These values maybe increased by the ratio of 1.70/1.33 for compli-ance with the acceptance criteria of chapter 5.Figure 6-13 from the BDM provides similar allow-able shear values for various materials other thanplywood. These values may also be increased bythe above ratio. Other useful design data andtypical connection details for wood stud shearwalls are contained in chapter 6 of the BDMLAlthough the BDM data is applicable to code level


Exist. under-reconnecting beambe removed and placed. See Del

Elevotfon

Existing Connecting Seem n Concrete Shear Wall

Existing slbeyond

b .Exist. relnf ornew dowels, as req'd

M1191M 1111 IM1101I s I I I I I s 1 1 1 1 1 4 4 i I I i W 11 * I

iiiuR lIHt lWlHIl 7E�zI -� �

New stirrup ties, -as required

-Extend existing slabrelnf. for anchorageIn new concrete beam

Detail I Section ax

Figure 68. Strengthening of existing connecting beams in reinforced concrete or masonry walls

stresses for new construction, similar details withthe increased stresses prescribed in the SDG aresuitable for seismic upgrading of existing woodstud walls.

(6) Steel stud walls. Existing steel stud wallscan be upgraded by bracing in the plane of thewall. Typical details are provided in figures 6-17aand 6-17b of the BDM. The indicated detailsprovide a capacity of 1000 lbs for code level forces(allowable stress plus a one-third increase). Thiscapacity may be increased by 1.70/1.33 for yield

level capacity.(7) Diaphragms.

(a) Wood floor framing. Typical details forwood diaphragms are provided in chapter 5 of theBDM. When the seismic evaluation indicates thatthe existing floor or roof system is inadequate forthe necessary diaphragm action, the seismic capac-ity of the existing system can be upgraded bymeans of a plywood overlay. The existing floor orroof covering will be removed so that the plywoodcan be applied to the existing subfloor or roof

6-27

TM 5-809-10-2/NAVFAC P-355.2VAFM 88-3, Chap 13, Sec B

New reinf..as required

Clean and roughenexist. concrete ormasonry surface

Section aa

Exist. rinf.concrete ormasonry wall

,Exist opening tobe filled-in

New dowels, epoxygrouted In drilledholes to match newrelnf. In opening

Elevation

Existing Reinforced Concrete or MasonryShear Wall with Opening to be Filled-In.

Figure 6-9. Strengthening of existing reinforced concrete or masonry walls by filling in of openings

sheathing. In some cases it may be desirable toremove the subfloor or sheathing to facilitate theinstallation of the necessary blocking and otherconnections similar to those shown in figures 5-33and 5-34 of the BDM. The upgraded diaphragmneeds to be evaluated for its capacity to distributethe seismic shear forces to the vertical resistingelements below and also for its capacity to provideresistance to the out-of-plane seismic forces on the

exterior walls. The horizontal deflection of wooddiaphragms will be checked, in accordance withthe provisions of chapter 6 of the BDM, to precludeexcessive out-of-plane deformation of masonry orconcrete walls. Table 5-6 in the BDM providesallowable shear forces for horizontal plywood dia-phragms. These values are to be increased by1.70/1.33 for the determination of capacity atyield. The diaphragm must also be able to resist

6-28


Existing unreinforcedmasonry wall

Two wythes of exist.masonry removed

New 10" concrete wall,reinf. as required

New wall anchors, *epoxy grouted Indrilled holes at2'-6" maximum// .spacing. a. way 'I

Figure 6-10. Strengthening of exis

the chord stresses generated by the inertia loadson the diaphragm as it spans horizontally betweenthe vertical resisting elements. Figure 6-14 indi-cates a detail whereby a continuous steel anglecan provide all of the above functions for a wooddiaphragm at a reinforced masonry wall. Figure6-15 indicates details for strengthening of wooddiaphragms in steel frame buildings.

(b) Concrete floor or roof systems. An exist-ing concrete floor or roof system can be seismicallyupgraded for diaphragm action by the addition of asuperimposed diaphragm slab as shown in figure5-8 of the BDM. Figure 6-16 shows a -detail of asuperimposed diaphragm slab at an existing ma-sonry wall. Diaphragm chords for upgraded con-crete diaphragms can be provided or supplementedby continuous steel angles similar to the detail infigure 6-14. An alternative procedure is to formthe chord with a new reinforced concrete beam asindicated in figures 6-16 and 6-17. Large open-ings in existing concrete diaphragms should beinvestigated to confirm that excessive shear or

ting

Exist concrete slab.shored and partially

/removed to exposeexist. reinf.

^~~ -

New slab dowels Intoconcrete wall

New concrete diaphragmchord beam. Rinf. asrequired

unreinforced masonry walls or piers

flexural stresses will not cause distress to theadjacent areas of the diaphragm. Figure 6-18indicates how additional reinforcement in the su-perimposed diaphragm slab can be used to providesupplementary trim bars for openings. An alterna-tive procedure for reinforcement of diaphragmopenings is to form a reinforced concrete beamaround the perimeter of the opening. An addi-tional alternative is to protect the opening withwelded structural sections forming a frame for theopening and anchored to the concrete. Inadequateshear transfer from an existing concrete dia-phragm to steel framing can be upgraded withshear studs similar to those in figure 6-19 exceptthat the studs would be welded and grouted inholes cored in the existing slab.

(c) Steel decking. The seismic capacity of exist-ing steel decking may be updated, in place, onlywhen it does not have a concrete fill slab or whenthe fill material can be readily removed. If theabove condition is met, the deck can be upgraded

6-29

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sc B

- - - - -

Way -Existing beam

Section a a

New steel angle, a.side, welded to steelplate. New anchor bolts,as required.

Figure 6-11. Bracing of heavy timber construction

to its maximum capacity by additional welding inaccordance with the details indicated in chapter 5of the BDM. Additional capacity, if required, canbe provided by a reinforced concrete fill as indi-cated in figure 6-19. If the existing steel deckinghas a concrete fill, but the composite assemblydoes not have adequate capacity, additional capac-ity can be provided by a superimposed diaphragmas is indicated in figure 6-16 for an existingconcrete slab.

6-30

(8) Foundations. Strengthening of existingfoundations is generally an expensive and disrup-tive procedure. If the existing foundations aredeficient because of the additional seismic loadsrequired by the provisions of this manual, it willusually be more cost effective to reduce the seismicloads on the existing foundations by redistributionof the lateral loads to other new or strengthenedresisting elements.

(a) Spread or strip footings. The bearing


cist wood ,. Exist. wood)Ists / diaphragm

New wood bolsterwith lag screwsto exist. beam

New wood bolster,,,bolted to exist.post

Existing foundation

7I

Exist. timberbeam

New steel plates, eachside, bolted to braceand post or beam

Exist, timber post

New steel plates, eachside, with welded angles.New anchor bolts, as req'd,

i ____ _to exist. foundation

Figure 6-12. Knee bracing of heavy timber construction

capacity of existing strip footings can be upgradedby underpinning as indicated in figure 6-20. Theunderpinning is performed in spaced segmentswith the strip footing and wall above providing therigidity to distribute the loads to the remainingportion of the foundation. As each section of thenew foundation is completed and cured it is preload-ed by jacking against the existing foundation.When all sections are complete, the space betweenthe new and existing footing is drypacked withnonshrink grout and the jacks are removed andtheir accesses are also drypacked. Similar proce-dures can be used to upgrade the capacity of aspread footing. The procedure is only practicablefor very large spread footings where a reasonablesegment can be undermined and underpinnedwithout significant impairment to the stability of

the existing footing.(b) Piles or drilled piers. The capacity of an

existing pile or drilled pier foundation can beupgraded by the addition of additional piles ordrilled piers. This will usually require removaland replacement of the existing pile or pier capand temporary shoring of the column or otherelement supported by the foundation. Figure 6-21indicates a typical detail for a pile foundationsupporting a steel column.

c. Replacement of existing deficient structuralmembers. Upgrading of deficient structural mem-bers by removal and replacement with larger orstiffer members or systems is a feasible, but notalways cost effective, rehabilitation procedure. Thereplacement procedures are essentially the sameas those described in paragraph 6-6d. The removal

6-31


New x to match existingsill plate. 2-IS boltswith plate washers

Figure 6-13. Strengthening existing wood stud walls with let-in bracing

procedures must be carefully planned and moni-tored so as to avoid disturbing construction whichis to remain and to provide for proper connectionsto the replacement construction. This may requiretemporary shoring or other means of support forthe existing construction to remain and carefulsequencing of the removal and replacement of thedeficient structural members. Figure 6-22 de-scribes the removal of an existing unreinforcedmasonry wall and replacement with a reinforcedconcrete wall.

d. Addition of new structural members.(1) Rigid frames.

(a) External frames. Existing buildingswhose lateral force resisting system consists ofmoment frames that do not comply with theacceptance criteria of chapter 5 may be strength-ened by the addition of supplementary externalrigid frames of reinforced concrete or structuralsteel. The effectiveness of this procedure dependson providing new frames of adequate strength and

6-32

rigidity to reduce the forces and deformation of theexisting frames to acceptable limits. The costsassociated with this strengthening technique mayexceed those for more conventional procedures(e.g., addition of shear walls or bracing); however,a significant advantage of this procedure is that itminimizes disruption of the existing facility asmost of the required construction is outside of thebuilding. An adequate existing diaphragm is re-quired, but the system can provide the necessarychord capacity as part of the new frame. Typicaldetails for a supplementary steel frame are shownin figure 6-23.

(b) Interior frames. Supplementary interiorframes may also be used to reduce the seismicforces and distortions of existing framing. Thedesign and construction procedures for new inte-rior frames in an existing building are similar tothose for the removal and replacement of existingdeficient structural members as described in para-graph 6{c.


New continuous steel-angle bolted, as req'd,to wall and new diaphragm

Kew anchor

-Exist. woodjoists

.Exist. oodsubf loot

Exist. woodblocking asreq'd for

diaphragm nailing

Exist. concreteor masonry wall

.,

Figure 6-14. Strengthening of existing wood diaphragms in reinforced masonry buildings

(2) Shear walls.(a) Exterior shear walls. The addition of new

exterior shears to a seismically deficient existingbuilding is often an attractive alternative becauseit minimizes disruption of the internal functions ofthe building. In wood framed buildings the shearwalls could be wood stud shear walls or reinforcedmasonry shear walls depending on the magnitudeof the seismic forces to be resisted and the relativecosts of the walls and their attendant foundationsand connections. In steel framed buildings orreinforced concrete or masonry buildings, the newshear walls will be either reinforced concrete orreinforced masonry. Figure 6-24 indicates theaddition of a new reinforced concrete shear wall inan existing reinforced concrete frame building.

(b) Interior shear wall. The addition of newinterior shear walls in an existing building may beseriously constrained by the need to maintain anessential function during the construction period.To minimize interference with the functional oper-ations, it may be necessary to consider alterna-tives that may be more expensive in terms ofmaterial and installation costs, but which willminimize the construction time and the disruptionof operation within the building. Steel shear wallshave been successfully installed under such condi-tions as indicated in figure 6-25. Prefabrication ofthe walls is utilized to the maximum extentpossible and temporary dust barriers are installedto protect adjacent functions in the building. Inbuildings that do not have the above constraints,more conventional alternatives, similar to those

described in paragraph (a) above, may be moresuitable. Although it is usually desirable to locatethe new shear walls along frame lines (i.e., fram-ing into existing columns and beams) to provideboundary members; to provide dead loads to helpresist overturning forces; and to take advantage ofexisting column foundations, other considerationsmay dictate wall locations away from the existingframe lines. This condition is illustrated in detail1 in figure 6-24. Except for very thick slabs, thisdetail will probably require supplementary mem-bers, such as the steel angles shown in the detail,to set as collector members extending beyond theshear wall to facilitate transfer of the diaphragmshear from the slab to the shear wall.

(3) Vertical bracing. The addition of new verti-cal steel bracing is usually a cost effective proce-dure for upgrading the seismic resistance of anexisting steel frame building. The new bracingmay be installed to supplement existing bracing orto reduce the seismic forces and displacements ofexisting moment frames. In low-rise buildings (lessthan about 6 stories) with average site conditions,the addition of bracing to a moment frame struc-ture will usually mean an increase in the spectralseismic demand as the greater stiffness of thebracing will almost ensure that the building willrespond at the maximum amplification of theresponse spectrum. Also, because of the greaterrelative rigidity of the bracing, it will usually berequired to resist a larger share of the seismicforces than the moment frames. Concentric brac-ing may be diagonal bracing, x-bracing, or k-

6-33


Provide special nailingfor shear transfer toexisting nailer

I,,

New superimposed plywooddiaphragm. See DOM,Chapter i, for typicalnailing requirements

Ecking xisti.o wood nailer. Providedeking additional bolting, as rq'd

for shear transfer from dia-

Existina steel phrag to steel beambean

Detafi 1

Wood Decking SupportedDirectly on Steel Beams

New wood blocking, as req'd,with special nailing for sheitransfer from diaphragm toexisting nailer

Existing timber decking.with superimposed plywooddiaphragm

I

Existing wood joists

Existing wood nailer New continuousProvide additional wood joist withbolting, as required special nailing

(See Detail 1) for shear trans-fer.

Existing woodblocking

--- - __ __

Detail 2

Joists Normal toSteel Beams

Detal 3

Joists Parallelto Steel Beams

Figure 615. Strengthening of existing wood diaphragms in steel frame buildings

6-34


Exist, masonrywall

New dowelsepoxy grouted In drilled hole

Figure 6-16. Superimposed diapi

bracing and is usually designed to act both intension and compression. In recent years eccentricbracing has been promulgated as a means toprovide the strength and stiffness of bracing withmuch of the ductility associated with momentframes. Figure 6-26 indicates typical details foreccentric bracing. In the determination of the type,members, and location of additional braced bays inan existing building an important consideration is

Exist. Masonry _ _wall

Exist. Slab y

Ne wels, smreq'd, epoxygrouted indrilled holes

New concrete chord beam.Reinf. as required

kragn

New superimposed concreteslab Reinforced as re-

/quired.

-Exist. concrete slab.Roughen surface forbond to new concrete

Pa slab at an existing masonry wall

the cost associated with the required modificationor strengthening of the columns, beams, and f Pundations as a result of the new bracing. Some ofthese costs may be significantly greater than thebracing itself so that the use of additional bracedbays may be justified if the forces can be reducedso as to eliminate costly modification of the exist-ing structural system.

(4) Horizontal bracing. A horizontal structural

Exist. slab relnf. to be/ extended into new concrete

Exist. reinf. concretereInf. slab. Provide temporary:rete shoring for partial re-

---ete,_ moval as shownnewconi

Cnura em,as req'd

Figure 6-17. Diaphragm chord for existing concrete slab

6-35

TM 5-809-10-21NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

Superimposeddiaphragm slab

,Trim bars

Exist. concrete slabs.-Roughen surface forbond with new concret

Typical slabreinf. as rej Section we

New trim bars In superimposeddiaphragm slab. Typical slabreinf. not shown

Vy A-4

OL\ t ~Exist.

I ,k

.r

---- - . 6-U

Plan

Figure 6-18. Strengthening of openings in a superimposed diaphragm

New shear studs. as req'd,welded through steel deck-to steel beam

New concrete fill.roinf. as req'4

stZG

Figure 6-19. Strengthening of existing steel deck diaphragm.

6-36


steel bracing system may be used as a diaphragmin existing buildings where the existing floor orroof system has not been designed for the requireddiaphragm action. This procedure will usually belimited to relatively flexible existing floor or roofsystems such as timber or steel decking where thehorizontal bracing can provide the necessary rigid-ity and transfer of the floor or roof shears to thevertical resisting elements. The bracing must beproperly connected to the floor or roof system topick up the inertia loads originating at that leveland must include the necessary chords and connec-tions to the vertical elements to provide thenecessary out-of-plane support for these elementsand to transfer the diaphragm shears to theresisting elements. Figure 6-27 indicates the useof horizontal bracing system in an existing steelframe building with concrete walls. It may not benecessary, in all cases, to provide crossbracing inall bays of the floor or roof system as shown infigure 6-27 if the existing system can be reliedupon for some diaphragm action. The bracingconfiguration in figure 6-27 assumes negligiblediaphragm capability (i.e., only adequate to trans-fer inertia forces between adjacent horizontalframing members) in the existing floor system.

(5) External buttresses. The use of externalbuttresses of reinforced concrete or braced struc-tural steel could be feasible for strengthening anexisting building. The buttresses may be designedto resist compressive forces only, in which casethey must be located on both sides of the buildingin each direction to be braced. If the building hasa structurally adequate diaphragm, the membersand location of the buttresses will be determinedto resist the calculated seismic forces and tominimize torsion. If the building has a flexiblediaphragm, the buttresses must be designed forthe tributary seismic forces and must be locatedwhere the existing framing can transfer the tribu-tary loads by strut action. For example, in anexisting steel frame building with a flexible dia-phragm, the girders in the transverse directionmay be assumed as receiving the seismic inertialoads from the secondary floor beams connected tothe girders and buttresses would be located ateach girder line. In the longitudinal direction, asimilar assumption would be made regarding thesecondary beams and buttresses would be locatedat every third or fourth beam assuming the exist-ing floor system is capable of transferring thetributary floor loads. Buttresses that are designedto resist both tensile or compressive forces may belocated on only one side of the building in eachdirection, but will require an adequate connectionto be made to the existing building to transfer thetensile forces to the buttress. Figure 6-28 indi-

cates the use of braced structural steel buttressesto strengthen an existing reinforced concrete build-ing.

(6) Structural additions. An existing deficientbuilding may be strengthened by a structuralbuilding addition that is designed to resist theseismic forces generated within the addition aswell as all or a portion of the forces from theexisting building. This alternative has the obviousadvantage of generating additional useful spacewhile upgrading the existing building. The designconsiderations are similar to those indicated in theabove paragraph for buttresses except that theadditional seismic forces from the new additionalso have to be considered in the design of theresisting elements.

6-5. Upgrading of nonstructural ele-ments

The evaluation of the adequacy of supports, an-chorages, or bracing of nonstructural elements toresist the imposed seismic forces and displace-ments in existing buildings will be based on theresults (story accelerations and interstory drifts) ofthe initial detailed structural analysis of the build-ing or, if extensive structural modifications arerequired, on the subsequent reanalysis of therecommended concept. Analytical and acceptancecriteria for these elements are provided in chapter9 with typical details for seismic upgrading. Ele-ments to be evaluated for upgrading will include:

a. Mechanical/electrical equipment (i.e., emer-gency motor generators, heating, air conditioning,and ventilation systems, electrical control panels,elevators, water and sewer lines, and sprinklerpiping).

b. Suspended ceilings and light fixtures.c. Nonstructural partitions.d Structural appendages (i.e., penthouses, para-

pets, canopies, and precast concrete curtain wallunits).

e. Glazing (i.e., large glass panels).t Miscellaneous (i.e., computer floors and free-

standing storage units).g. Storage shelving (i.e., supporting hazardous

or essential items).

6-6. Concept submittalA concept submittal will be prepared for reviewand approval by the approval authority. The sub-mittal will comply with agency standards and willgenerally represent 25 to 35 percent of the effortrequired to complete the design of normal projects.The concept submittal will include the followingelements:

a. Basis for design. This will include the accep-tance and design criteria; a summary description

6-37

TM 5-809-10-2NAVFAC P-355.2AFM 88-3, Chap 13, Sc B

'$_- Existing ConcreteBearing Wall

iP

PGround surface

_-_-_ --- _-Pd 4p

Existing continuous wall footing N

11 1 1 liM-tY~~~~~~~~~~~~~1

1( | (1) | 2) ( 3) (1|) ( 5) |(6) (1) (2) ({3)

L0Elevation a

II

t

New

Section a

Sheet I of 2

Figure 6-20. Underpinning of an existing footing. (Sheet 1 of 2)

6-38


Construction Sequence:

1. Perform excavation and underpinning sequentially In widely spacedsegments as shown [e.g. segments designated ()1.

2. Pour new concrete footing with jacking pocket and gap for drypacking.

3. When new concrete In () has attained adequate strength. place jacksto preload footing.

X Repeat procedure for segments (2) and (3).

5 When jacks have been placed and loaded for (1). (2). and (3). drypack (2)and remove Jack.

6. Proceed with remaining segments until complete footing Is underpinned.

Sheet 2 of I

Figure 6-20. Underpinning of an existing footing. (Sheet 2 of 2)

of the deficiencies identified in the detailed struc-tural analysis; a narrative description of the alter-native upgrading concepts; and justification for therecommended concept.

b. Calculations. Edited, checked, and indexedcalculations will be included in the submittal tosupport the design of the upgrading concepts.

c. Cost estimates. Comparative cost estimates forthe alternative concepts and a complete prelimi-nary cost estimate for the recommended concept.

d Schematic drawings. Schematic drawings willbe prepared for the recommended concept. Thedrawings must be adequate to describe the nature,

extent, and location of work required and, as aminimum, will include foundation and framingplans, typical sections, and typical connection de-tails.

e. Outline specifications. Outline specificationswill be prepared to describe the type and grade ofstructural material and procedures by reference tostandard or industry specifications.

f Schedules. The concept submittal will includethe estimated number of man-hours to completethe design and estimated schedules (calendar days)for the design submittals, reviews, bidding, con-tract award, and construction.

6-39


Note:

Existing framing to be temporarilyshored to permit removal of exist.pile cap and column base plate.Drive new piles; weld new baseplate and moment connection tocolumn; pour new pile cap; anddrypack under base plate

\ i ~- Extend pre-stress strands

\ | { F--tnto pile cap

Section

Existing pi

sLNew piles"

New pile ca

New prestressedconcrete piles

Existing columnand base plate

) IaExisting pile capto be removed

Plan

Figure 6-21. Upgrading of an existing pile foundation

6-40

TM 5-809-10-2INAVFAC P-3SS.2/AFM 88-3, Chop 13, Sec B

- . >w---

Exist. footlu-______*to remain I

I

I

.0 . .

. i

..

1_-I

Exist. unreinforced---- amasonry walI to be

removed

New reinforcedconcrete wall

*- _ _ , _ .

-i -

-4

I

I

Plan

unrelnforced

New reinf.concrete wal

IC

I

Exist, concreteslab

11I L A

New slab dowels,as required

New dowels to matchwall reinf. epoxy -grouted in-drilledholes

I

Note:

Provide temporary shoring forexisting slab, as required,to allow partial removal andconnection to new reinforcedconcrete wall

Existing footingto remaIn

Section

Figure 6-22. Removal and replacement of an unreinforced masonry wall

6-41


Section a

a F

Steel plate, spacedas required for shertransfer

New ductile moment-resisting steel frame - -

b Vt

New column foot ina-

iIII±

.1-u-...

4I

Continuoussteel ST

III Exist. concrcteframe building )

- X

b

Exist. column'It o -I footing beyond

Section at Existing Wall

Sheet I of 2

Figure 6-23. Upgrading an existing building with external frames. (Sheet I of 2)

6-42

TM 5-809-10-2INAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

Existing concreiframe column

Existing columnfooting

Existing tie

New steel columnand base connection

New column footinglocated to avoid -interference withexisting columnfooting

Section bb

Sheet 2 of 2

Figure 6-23. Upgrading an exiating building with external frames. (Sheet 2 of 2)

6-43

TM 5-809-10-2NAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

Exist. concreteslab and beam

tiir. " ANew shear walland footing

I

* 4

f4

I

v-r____cw shear wall,relnf. as req'd

Remove andreconstructexist. slab,as req'd

Section - Section b-b

Exist. slaband beams 1-I q0

Dowels to matchvertical reinf.epoxy grouted Indrilled holes

I.~~~~~A I

;//// y -J~

Exist, concretecolum

M4 -L - 11 11 11 I II

a | l l _ t New concreteI_~_w _ _ >J _ _ shear w llJL.____ I reinf. as rq'd

f. . - . .,- r1_-.I = - I . -

Dowels to match -horizontal rnf. = � - =- I- -4-- 4-- 1lb

_ = - 4 1 - - 4-g.I-I III . 1.1 1 I tII

Exist. coumnfoot Ing

-- W� I

-1-1- I-I - I

New shear~ wall footing

la

Elevation

Sheet I of 2

Figure 6-24. Strengthening of an existing concrete frame building with a reinforced concrete shear wall. (Sheet I of 2)

6-44

TM S-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

Provide access holes Inexisting slab for pouringor pumping wall below

Cont. angles, may extend beyond wall. If yeq'd, ascollector members

When new shear wall extends-above existIng slab, extendand grout vertical relnf.In drIlled holes.

7- Exist. concrete slab

Terminate new wall pour 2"below slab soffet and dry-pack wIth grout

New concrete shear wall,relnf. as rqd

Detail

Sew Concrete Shear Wallat Existing Slab

( Sheet 2 of 2

Figure 6-24. Strengthening of an existing concrete frame budlding with a reinforced concrete shear walL (Sheet 2 of 2)

p6-45

TM 5-809-10-2NAVFAC P-355.2/AFM 88-3, Chop 13, Sc B

J~~~~~~~~~~~~

L

_~~~~~~~1 a

Ml - COIVI~~~~I

ii

Iv 2~~~~~~

'}L' LIZ X-. 1 a~~~~

I -

'1} ~~A Ji*l"#

-C _ )

I L I I I

6-46


Spacer.as eq'd

Steel channels backto back. Size as requIred.

Section .

Existing structuralsteel moment frame

Elevation

Figure 6-26. Strengthening of an existing building with eccentric bracing

6-47


Exist. floorbe .

nt frame

New connection plateswelded to colunm andbottom flange of floorbeam

Section A-A

Section a-aExist. steel ndmentframe, typical ,

Exist. steel

Exist. steelfloor beams,typical

FLOOR FRAMING PLAN

Sheet I of 2

Figure 6-27. Strengthening of an existing steel frame building with horizontal bracing. (Sheet I of 2)

6-48


East, floorbem

New connectionplate

7jbm/

bL

Section 5-9

welded to flange offloor be

Section b-b

ew ST

'LI

Exist, floorbeam

New connection plate

ZZZZ jc.~~~~

Ie

Section C-C Section c-c

Sheet 2 of 2

Figure 6-27. Strengthening of an existing steel frame building with horizontal bracing. (Sheet 2 of 2)

6-49

TM 5-809-10-2NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B f

New structural tubebraces, slotted andwelded to ST at wall.and plate at column.Typical at roof, 2ndand 3rd floors

Exist. concrete

New stealbuttresses,

New bolts, epoxygrouted n drilledholes ~1.. _ _

Existing concretebuilding )

ISection a

Exist, wallfooting .

b

Exist. columnfooting

New piles or drilled piersfor bearing and uplift

Section b-bSection at Existing Wall

Figure 6-28. Braced structural steel buttresses to strengthen an existing reinforced concrete building

6-50


CHAPTER 7

COST BENEFIT ANALYSIS

7-1. IntroductionThis chapter provides guidelines to evaluate thecost effectiveness of upgrading seismically defi-cient existing buildings on the basis of data ob-tained from the preliminary evaluation, the de-tailed structural analyses, and the development ofdesign concepts. Criteria are provided to determinethe cost effectiveness of taking no action (i.e.,leave "as is"), upgrading or replacement of exist-

ing deficient buildings.

7-2. Earthquake riskMethodology for the specification of ground motionis provided by chapter 3 of the SDG.

a. Probability of occurrence. On the basis ofavailable data and state-of-the-art techniques, esti-mates can be made on the probability of occur-rence of earthquake motion at a particular site

Table 7-1. Probabilities of exceedance of peak ground acceleration in 50 years, NAS Moffett Field, California

PROBABILITIES OF EXCEEDANCE OF PEAK GROUND ACCELERATION

IN 50 YEARS. NAS MOFFETT FIELD. CALIFORNIA

Probability ofPCA'S Exceedance

0.0 1.0000

0.05 .9990

0.1 .9563

0.15 .7698

0.2 .5803

0.25 .4452

0.3 .3383

0.35 .2571

0.4 .1979

0.45 .1518

0.5 .1166

0.55 .0901

0.6 .0706

0.65 .0542

0.7 .0405

0.75 .0310

0.8 .0241

0.85 .0179

0.9 .0136

0.95 .0101

1.00 .0071

7-1


that is caused by a variety of earthquakes atdifferent sources. The results of such a study canbe summarized by a curve that plots number ofoccurrences per year that equal or exceed variouslevels of peak horizontal ground accelerations(PGA). An example of this relationship is shown intable 7-1.

b. Response spectra for selected seismic events.The various levels of earthquake ground motionsthat are postulated for a particular site during aselected period of time can be represented by aseries of response spectra. For example, a set ofresponse spectra, with appropriate damping valuesfor elastic and post-yield responses, can be used torepresent the earthquake demand for each of thePGA levels in table 7-1. The response spectrashown in figure 7-1 are normalized to 1.0g. Thesespectra can be used for any PGA level by selectingthe appropriate damping levels and multiplyingthe spectral ordinates of the selected curves in thefigure by the desired PGA level.

7-3. Domogeability of the structureThe results of the preliminary evaluation as deter-mined by the procedures in paragraph 4-2d willgive an indication of the damageability of thestructure. However, consideration should be givento the degree of accuracy used in the analysis ofthe structure. Due to the approximate nature ofthe damage estimate procedures, the results cansometimes be misleading. A review of the analysisshould be made to determine if the amount ofpredicted damage has been overstated or under-stated. The results of the detailed analysis ofchapter 5 can be used to more accurately describethe capacity of the structure, especially if method2 was used.

a. Capacity to resist earthquake without damage.If the existing structure is able to conform to theacceptance criteria of paragraph 5-2, it is assumedthat there will be no damage for EQ-I and little, ifany, damage for EQ-II. The effects of EQ-I can be

dd

6.60

IV1'C

U4

6;

Ca

U

.C0b.

I

0.5 1.0 I

Period (Seconds)

Figure 7-1. Acceleration response spectra normalized to 1.0g.

7-2


approximated by the damage control checkprocedure described in paragraph 6-3e.

b. Repair costs. If the results of the detailedanalysis indicate that damage will occur in theevent of EQ-II, estimates will be made to establishcosts to repair for the damage associated with eachof a series of earthquake response spectra such asdiscussed in paragraph 7-2b. The repair costs maybe based on the damage estimate procedure de-scribed in paragraph 4-2 using the capacity deter-mined in the detailed analysis described in para-graph 54. If sufficient data are available, it ispreferable to make a more rational estimate basedon an itemized list of repairs. The list mightinclude such items as painting and cosmetic re-pairs, repairs to partitions, repair cracks in con-crete elements, replacement of steel braces, repairsto diaphragms and connections, repair to shearwalls, and replacement of major structural ele-ments. The methods and degree of effort used tomake the cost estimates will be dependent on thesize, type, and function of the structure.

7-4. Annualized repair costs withoutseismic upgrading

Actual costs for damage predictions are difficult todefine. In addition to technical evaluations, thereare also social, economic, and administrative deci-sions that should be considered. For example, afteran earthquake occurs that causes some damage toa structure, four general courses of action may beavailable: do nothing; do minimum repair and/ormodifications; do moderate repair and/or modifica-tions that may upgrade the capacity of the struc-ture; or tear down the structure and rebuild. Adecision on the course of action must be madeafter each earthquake. A solution based on thissort of approach would require the use of decisiontheory; however, development of a methodolgyusing decision theory has been considered to be toocomplex for use in this manual. To simplify theprocedure, one decision was made that governs allthe structures for any size earthquake. If will beassumed that after each earthquake, the buildingwill be repaired to restore it to the pre-earthquakecondition. The cost of such repairs is the damagecost determined in paragraph 7-3, above. A proce-dure to estimate the annualized repair costs anddetermine their present value is outlined below:

a. Select a series of ground motion responsespectra that represent all postulated earthquakesas described in paragraph 7-2b.

b. Determine the number of seismic events rep-resented by each of the above earthquake spectraduring the useful life of the building. The usefullife of an existing building will be assumed to be

not less than 25 years, unless otherwise directedby the approval authority.

c. Estimate the repair costs for each of theearthquake spectrum in a, above.

d. Multiply each of the repair costs, estimatedin c above, by the number of seismic eventsassociated with each spectrum as determined in babove.

e. Calculate total repair costs, R, by totaling therepair costs for all the postulated earthquakes.

f Obtain the annualized repair costs by dividingthe total repair costs, R, by the time span, n, usedin b, above.

g. Calculate the present value of the annualizedrepair costs by:

n +PVR = R/n T1+i) (eq 7-1)

n=1where PVR = Present value of annualized repair

costsR = Total repair costs during the useful

life of the buildingi = Assumed average interest rate for

next n yearsj = Assumed inflation rate for next n

yearsn = Useful life of the building (i.e., not

less than 25 years, unless otherwisedirected).

7-5. Cost of seismic upgradingThe recommended concepts developed in accord-ance with the guidelines of paragraph 6-3 will beused for estimating the costs of seismic upgradedbuildings.

7-6. Annualized repair costs after seis-mic upgrading

The acceptance criteria specified in paragraph 5-2imply that essential buildings conforming to thesecriteria will be subjected to minor damage fromthe ground motion associated with EQ-II, but thebuildings will be capable of performing their es-sential functions with little or no interruption ofthese functions. For high-risk and all other build-ings, the criteria imply that structural collapsewill be precluded, but that some structural dam-age is to be expected. These criteria also implyacceptance of the risk of additional damage fromground motion more severe than that associatedwith EQ-fl. The repair costs associated with thisseismic damage to the recommended concepts willbe calculated as described in paragraph 74,above, for the existing building models but withthe new structural capacities resulting from theupgrading modifications.

7-3


7-7. Cost versus benefits of a recom-mended upgrading concept

a. Cost of no action. The present value of theannualized repair costs to the existing buildingwill be determined by the procedures outlined inparagraph 7-4.

b. Total costs of the recommended upgradingconcept. The total cost associated with the recom-mended concept will be the upgrading constructioncost, determined in paragraph 7-5, plus thepresent value of the annualized repair costs deter-mined in paragraph 7-6.

c. Replacement costs. The cost of constructing anew building to replace the existing building willbe estimated. Since this cost will be used only forcomparison with the costs determined in para-graphs a and b above, the same degree of refine-ment will be used. In most cases, the replacementcost may be determined from the inventory of realproperty (see para 2-2) or estimated from repre-sentative costs per square foot of similar construc-tion in the area adjusted, as necessary for size,inflation, and other factors.

d. Economic analysis. An economic analysis ofthe above costs will be made by comparison of thevarious costs outlined in paragraphs a, b, and cabove.

e. Example. An example of a cost benefit analy-sis, taken from a recent study performed under theauspices of the Naval Civil Engineering Labora-tory (NCEL), is summarized in tables 7-2 and 7-3and is described below.

(1) Description of building. The building is atwo-story reinforced concrete structure designatedas unaccompanied enlisted personnel housing(UEPH). The lateral force resisting system iscomprised of the concrete roof and floor dia-phragms and the reinforced concrete shear walls.The elastic capacity of the longitudinal shear wallsoccurs at a PGA of 0.39g. In the transversedirection, the elastic capacity occurs at a PGA of0.12g and is limited to flexural yielding of shortinterior shear walls and their connecting gradebeams.

(2) Earthquake demand The seismic hazard atthis site (NAS Moffett Field, California) is repre-sented in table 7-1. Corresponding values of EQ-Iand EQ-I would be about 0.23g and 0.57g respec-tively. The site response spectra, shown in figure7-1, are normalized to a PGA of 1.0g.

(3) Number of seismic events. The useful life ofthis building was assumed to be 50 years. Thenumber of seismic events, that can be expectedduring this 50 year period, equal to or exceeding agiven PGA value, was calculated for PGA incre-ments of 0.05g from the data in table 7-1 usingthe Poisson probability relationships. The differ-

ence between the number of events for consecutiveincrements of PGA is designated as NEI in tables7-2 and 7-3, and this difference represents theexpected number of events of a severity bracketedby the two PGA levels (e.g., in table 7-2, the NEIvalue of 1.6616 represents the number of seismicevents expected in 50 years with a PGA between0.lOg and 0.15g).

(4) Damage estimates. Estimates of damage foreach PGA increment were calculated using proce-dures similar to method 2 as described in para-graph 5-3f For purposes of this study, the totaldamage was defined as:

DE = D +D 2 + D3 + D4 RC2

(eq 7-2)

where DE = average total damage for a seismicevent corresponding to a given PGAlevel at the site

DI = total damage when full PGA is ex-perienced in N/S direction and 0.75PGA in E/W direction

D2 = total damage when full PGA isexperienced in E/W direction and0.75 PGA in N/S direction

D3 = damage to equipment which is un-coupled from building damage, ex-cept under collapse conditions, andrelated only to PGA

D = damage to contents which is uncou-pled from building damage, exceptunder collapse conditions, and re-lated only to PGA

RC = replacement cost of building andcontents

(5) Replacement and modification costs. Thebuilding upon which this study was based contains13,760 sq. ft. and has a current replacement cost of$1,106,000 plus contents valued at $97,600. Astrengthening scheme was developed to increasethe elastic capacity of the buiding in the trans-verse (north-south) direction to a level correspond-ing to a PGA of 0.20g. Strengthening is notrequired in the longitudinal (east-west) direction.The modified building would be substantially incompliance with the acceptance criteria of EQ-Iand EQ-fl and the estimated modification costsare $32,700.

(6) Total cost of repairs. The total damage,TD, in a PGA interval is defined as the averagedamage cost in the interval and is calculated bythe number of events, NEI, multiplied by theaverage total damage per event, DE, for twosuccessive PGA levels (e.g., in table 7-2, and TD

value of $6,977 = 0.2791 x 15,000 + 35,000 ). The2

averaging of the two DE values is required be-

7-4

TM S-809-10-2/NAVFAC P-3SS.2/AFM 88-3, Chap 13, Sec B

Table 7-2. Summary of a cost beneit study for an existing building without seismic upgrading

PGR NE I Di D2 D3 D4 D£ TD

.05

.10

. 15.20.25.30.35.40.4S.58.55.68. 6S.70.75.80.85.90.95

1.00

3.7774.6616.6006.2791.1762.1157. 6767. VM59.6487.0296.0212.0175.e144.0099.0071.0063. 8044.6035. 8030

O.6.

4600.20000.3708.65000.83080.

112000.141000.170808.224808.663000.663M88.663000.663000.663000.663000.663000.663000.663000.

O.O.

00.400.

17600.3008M.4706.65000.

1130.174000.236000.6630M0.663088.663880.66380.663008.663008.663000.6630B0.663088.

0.O.

1000.2608.

4008.8000.

14000.23008.

32000.

_ew.

lB0800.186008.

18600.18600.186000,186000.186000.186080.

186008.

0.0.6.

10.4000.9000.

1400.£9000.

23000.25000.2708.9BOOO.98000.9800O.98000.99000.98000.96000.9ss0.980.

O.0.

3500.15000.35008.64508.93000.

130508.182M08.238008.307000.94700.947000.947080.947808.947008.947808.947000.947008.947000.

O.O.

2908.Z555.6977.8766.9115.8568.8732.8S39.8054.

13295.16565.13619.9330.6719.5997.4137.3354.2866.

R 143097.

DIFFERENTIAL RATE -INTEREST RATE aINFLATION RATE

C =

PVR TC -

3.08%8.00%5.00%

6.77639.77839.

NOTATION

PSA aNEI a

DI a

02-03 -VA a

PEAK 6ROUND ACCELERATION IN 6 UNITSNO. OF SEISMIC EVENTS BETWEEN PRIOR ND CURRENT PGA

STRUCTURAL & ARCHITECTURAL DAMAGE, N-S EARTHOUAKESTRUCTURAL ARCHITECTURAL DAMAGE, E-U EARTHUAKEELECTRICAL * ECHANICAL EUIPMENT DAMAGE

CONTENTS DAMAGE

DE - TOTAL DAMAGE PER EVENT- (D1+D23/2+D3+D4 WERE (D1*2)/24D3+D4 RC

TD - TOTAL DAMAGE IN THE PGA INTERVAL

- NEI(PRIOR DE CURRENT DE)/2

R a TOTAL COST OF FUTURE DAMAGERC a REPLACEHENT COSTCM a COST OF MODIFICATIONSPVR = PRESENT VALUE OF COST OF FUTURE DAMAGE

ASSUMING DAMAGE SPREAD UNIFORMLY OVER 50 YEAR PERIOD

TC - TOTAL COST- PVR 4 CM

7-S

TM 5-809-10-21NAVFAC P-355.2/AFM 88-3, Chop 13, Sec BTable 7-3. Summary of a cost benefit study of an existing building with seismic upgrading

P6A NEI DI D2 D3 D' DE TD

------- ---- -

.05

.10

.15

.2o

.2s

.30

.3S

.40

.45.5G. 5.60.65.70.75.8a.85.90.95

1.80

3.7774

1.6066

.2791

.1762

.1157

. 0767

. 0559

.0407

.0296.0212.0175.0144. 099.0071.0063.0044.0035.0030

0.0.0.0.

13000.300.6000.90000.

120000.150000.194000.24400.696000.696000.696000.696000.696000.696000.696000.696400.

O.6.O.0.

0.

19000.3000.8800.

152000.216000.696000.696000.696000.696000.696000.696000.696000.696000.696000.

0.0.0.S.

1060.3000.7060.

13000.22000.31000.400.

126000.186000.186000.1860a0.18ae.186000.186000.186000.186000.

O.0.O.

1000.UOO.4000.900

14000190.23000.250OO.2700.66000.98000.98o00.98000.98000.98000.98000.98000.9800.

O.

O.100.

31600.60500.92000.

149000.207000.*72000662000.980000.

980000.

980000.980000.

980080.

0.O.

300.1744.3744.5296.5846.6734.7238.7079.9903.

14361.14094.9656954.6206.4281.3471.2966.

R 109871.

DIFFERENTIAL RATEINTEREST RATEINFLATION RATE

a

a

3.00S8.00%S. 0%

CM a

PYR a-C

32700.59766.92466.

NOTATION :

PGA - PEAK ROUND ACCELERATION IN UNITSNEI a NO. OF SEISMIC EVENTS BETWEEN PRIOR AND CURRENT PGA

Dl a STRUCTURAL ARCHITECTURAL DAMAGE, N-S EARTHKUAKED2 a STRUCTURAL & ARCHITECTURAL DAMAGE, E-W EARTHQUAKED3 a ELECTRICAL MECHANICAL EQUIPMENT DAMAGED4 a CONTENTS DAMAGE

DE * TOTAL DAMAGE PER EVENTa (DI+D2)/2+D3+D4 WHERE (D1+D2)/2+D3+D4 ( RC

TD a TOTAL DAMAGE IN THE PGA INTERVALa NEI*(PRIOR DE * CURRENT DEI/2

R a TOTAL COST OF FUTURE DAMAGERC a REPLACEMENT COSTCM a COST OF MODIFICATIONS

PVR - PRESENT VALUE OF COST OF FUTURE DAMAGEASSUIING DAMAGE SPREAD UNIFORMLY OVER 50 YEAR PERIOD

TC a TOTAL COSTa PVR + Cm

7-6


cause the NEI values represent all seismic eventsexpected to occur between the two successive PGAvalues and the damage is assumed to vary linearlybetween the two PGA levels. The total cost ofrepairs, R, is defined as the sum of the totaldamage costs, TD, for all the PGA levels.

(7) Economic analysis. The economic analysesfor this example were performed assuming aninterest rate, i, of 8 percent and an inflation rate,j, of 5 percent.

(a) Existing building. Table 7-2 indicatesthe repair cost analysis for the existing (unmodi-fied) building. The results of the analysis are asfollows:

Total cost of repairs, R, = $143,097Present value of cost ofrepairs, PVR, - $ 77,839

(b) Upgraded building. Table 7-3 contains asimilar repair cost analysis for the modified build-ing as follows:

Upgrading costs = $ 32,700Total cost of repairs, R, = $109,871Present value of cost ofrepairs, PVR, - $ 59,766

(c) Economic analysis. The above roof analy-ses indicate that the present value of the antici-pated repair costs of seismic damage to the build-ing, over its useful life, will be $77,839 if thebuilding is not upgraded. If the buiding is up-graded to compliance with the criteria of thismanual, the present value of the anticipated re-pair costs will be reduced to $59,766, but theadditional cost of $32,700, for the modificationresults in a total cost of $92,466. These total costs,with or without the upgrading modifications, aresignificantly less than the replacement costs of the

building, equipment, and contents. Therefore, re-placement need not be considered as an option.

(8) Conclusions and recommendation. Theeconomic analysis indicates that upgrading thisbuilding is not cost-effective. The detailed struc-tural analysis indicated that the existing buildingpossessed adequate post-yield capacity to precludecollapse so that the life safety of the occupants isnot in jeopardy. Therefore, unless there are otheroverriding considerations, seismic upgrading ofthis building should not be recommended.

7-8. ReportA report will be prepared for review by theapproval authority and for formulating the deci-sion as to whether the building should be up-graded, replaced, or left as is. In addition to theeconomic analysis, social, political, and adminis-trative considerations will be addressed. Thesemay include the impact of the potential seismichazards on life safety of the occupants or to thepublic (e.g., collapse of a facility containing haz-ardous materials); current and future use of thebuilding and its importance to the mission of theactivity; costs associated with temporary interrup-tions of use during the upgrading and/or repairwork; functionability of the existing building (e.g.,are there functional problems that could be cor-rected during the upgrading work?); and the his-toric significance of the building. A discussion ofthese and other appropriate considerations will beincluded in the report with a qualitative evalua-tion applicable to each building in support ofrecommendations that will be made as to action tobe taken for each building.

7-7

TM 5-809-10-2/NAVFAC P-3S5.21AFM 88-3, Chop 13, Sec B

CHAPTER 8

FINAL DESIGN AND PREPARATION OF CONTRACT DOCUMENTS

8-1. GeneralUpon authorization of the approval authority, thefinal design of the approved concept will be imple-mented and the necessary project constructiondocuments will be prepared in accordance with therequirements of the Basic Design Manual and theapplicable provisions of the SDG and this manual.

8-2. Final DesignThe final design will be done on the basis of theresults from the detailed structural analysis, de-velopment of design concepts, and the cost benefitanalysis as directed by the approval authority. Thefinal design will include a complete analysis of theupgraded structure, completed drawings of alldetails for the project, and a detailed cost estimate.The final documents will be complete in them-selves, without the need to refer to the previousanalysis and development work.

8-3. Preparation of project documentsa. Design analysis. A design analysis conform-

ing to agency standards will be provided with finalplans. This analysis will include seismic designcomputations for the determination of earthquakeforces on the building, for the structural evalua-tion of the existing building, and for the upgradingof the existing structure, including stresses in thelateral-force-resisting elements and their connec-tions, and the resulting lateral deflections andinterstory drifts. The first portion of the designanalysis, called the Basis of Design, will containthe following specific information:

(1) A statement on the methodology used fordetermining the ground motion criteria and adescription of the response spectra for which theexisting building will be evaluated and the up-graded structure will be designed.

(2) A description of the existing structuralsystem and the structural system selected forupgrading the building to resist lateral forces.

Include a discussion of the reasons for its selection.If irregular conditions exist, a statement describ-ing special analytical procedures to account for theirregularities will be submitted for review andapproval by the approval authority.

(3) A statement regarding compliance withthis manual, including the values selected fordamping, the criteria used for capacities and defor-mations of structural elements, and the method todetermine deformation compatibility between ex-isting and new structural elements.

(4) Any possible assumed future expansion forwhich provisions are made.

b. Drawings. Preparation of drawings will con-form to agency standards for ordinary constructionwith the following additional specific requirementsfor seismic construction:

(1) Preliminary construction drawings willcontain a statement that seismic design will beincorporated in accordance with this manual. TheBasis of Design submitted with these drawingswill include the information outlined in para-graphs a(l) through a(4) above.

(2) Construction drawings for seismic areaswill include the following additional special infor-mation:

(a) A statement on the seismic ground mo-tion criteria including the design peak groundaccelerations and related response spectra.

(b) A statement on the lateral-force designcriteria including a tabulation of the periods ofvibration and equivalent design lateral forces andother factors.

(c) Assumptions made for future extensionsor additions.

c. Specifications. Preparation of specificationswill conform to agency standards for ordinaryconstruction with additional specific requirementsthat relate to seismic construction and to upgrad-ing of existing construction.

d Cost estimate. Prepare a detailed cost esti-mate for the upgrading project.

8-1

RM 5-809-10-2/NAYFAC P-355.2/AFM 88-3, Chap 13, Sec B

CHAPTER 9

SEISMIC UPGRADING OF NONSTRUCTURAL ELEMENTS

9-1. IntroductionThis chapter prescribes guidelines for evaluatingseismic resistance of nonstructural elements inexisting buildings that must remain intact orfunctional after a major seismic disturbance. Theprovisions of this chapter consist of a qualitativeevaluation based on available pertinent design andinstallation documents and on-site inspection, anda detailed analytical evaluation using either adynamic approach prescribed in the Seismic De-sign Guidelines (SDG), chapter 6, or a staticapproach prescribed in the Basic Design Manual(BDM), chapters 9 and 10. This chapter alsodiscusses modes of damage to nonstructural ele-ments and their anchorages and suggestedstrengthening measures for correcting seismic defi-ciencies identified in the evaluation of existingstructures.

9-2. Acceptance criteriaThe acceptance criteria for the seismic resistance,details of anchorages, and performance of existingnonstructural elements will be essentially as pre-scribed in the BDM andlor SDG. However, ifexisting elements or their anchorages do not con-form to the above criteria, a tolerance of 15percent overstress (i.e., 15 percent understrength)is acceptable if required seismic upgrading wouldbe an excessively expensive and disruptive process.

9-3. General considerationsa. Elements to be considered. Nonstructural ele-

ments, which are generally categorized as architec-tural, mechanical, or electrical, include items thatare housed in or on the building, as well asportions of the building that are not part of thestructural system. Some nonstructural elementsare classified as essential systems. Essential sys-tems include all elements that are needed for theperformance of emergency services or that may, bytheir failure, cause life hazard or impair theperformance of services. These systems are out-lined in SDG, paragraph 6-7 and table 6-3.

b. Vulnerability to seismic damage. Damage canoccur to nonstructural elements from two basictypes of motion: large story accelerations thatcause elements to topple, fail the anchor supports,or cause damage; and large interstory displace-ments that will cause damage to elements rigidlyattached to the adjacent floor slabs. In addition,the presence of rigid nonstructural elements can

affect the performance characteristics of the struc-tural system. For example, the inclusion of anunreinforced masonry wall, tightly fitted within astructural steel framing system, will greatly in-crease the stiffness of the structure, will increasethe force level due to the shortened period, andwill change the distribution pattern of forces tothe structural elements. While the nonstructualelements can generate unexpected forces in thestructural system, so does the structural systemcreate unexpected forces in the nonstructural sys-tem. Furthermore, the failure of one element mayultimately cause the failure of another element oran entire system.

c. Reasons for seismic upgrading. There aregenerally four basic issues in the decision-makingprocess to decide whether nonstructural elementsare in need of upgrading and to what extent theupgrading is needed.

(1) Functional loss. Nonstructual damage maycause serious postearthquake disruption in essen-tial services and productivity.

(2) Life safety. Nonstructural damage may in-jure people.

(3) Economic loss. Nonstructural damage maybe costly.

(4) Structural interaction. Nonstructural ele-ments may interact with structural componentsand may change the overall structural behavior,which can be beneficial or harmful to the struc-ture.

9-4. Qualitative evaluationBecause of the great number of nonstructuralelements and systems in existing buildings, aqualitative evaluation is made prior to a detailedquantitative evaluation to determine the generalsusceptibility to damage of the nonstructural ele-ments and systems under investigation. The quali-tative evaluation includes an assessment of con-formance with minimum design and installationrequirements, the need for detailed quantitativeevaluation as described in paragraph 9-5, and therequirements for seismic upgrading. The followingfactors should be considered in the decision-making process:

a. Classification. This factor is based on theclassification of nonstructural elements in accor-dance with function, life safety, and economicrequirements. The following is an order of priorityof importance:

(1) All nonstructural elements that are housed

9-1

RM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

in an essential facility with special attention toessential systems required for life safety andpostearthquake operations.

(2) Essential systems housed in a high-riskfacility.

(3) Essential systems housed in other build-ings.

(4) All nonstructural elements that are notcovered above.

b. Building and site characteristics. The vulner-ability of nonstructural elements are dependent onthe amplitude of ground motion (e.g., responsespectra of EQ-I and EQ-I) and the dynamicresponse characteristics of the building (e.g., peri-ods of vibration and mode shapes). Data from thestructural evaluation of the building will aid inthe evaluation of nonstructural elements.

(1) Flexible equipment is susceptible to dam-age when its period of vibration is in tune withthe natural periods of the building.

(2) Elements attached to adjacent floors aremore susceptible to damage when located in flexi-ble buildings.

c. Seismic vulnerability. A qualitative evalua-tion requires judgment and experience on the partof the engineer in assessing seismic vulnerabilityof nonstructural elements. Possible modes of fail-ure must be anticipated in order to identify theelements most susceptible to damage from earth-quakes. Table 9-1 compiles a listing of types ofdamage that should be considered in the evalua-tion. This is not presented as an all inclusivelisting, but is presented as a guideline on the basisof experience and observations by others.

d. Field inspection. Many of the installation de-tails of nonstructural elements are often omittedfrom drawings because of common constructionpractices that have left many of these decisions toproduct manufacturers and installers. Therefore, itis important that design and installation details ofnonstructural elements, especially essential ele-ments, be investigated thoroughly during onsitqfield inspection. Furthermore, the observed exist-ing conditions should be compared with idealizedconstruction and strengthening practices, as rec-ommended in paragraph 9-6. Any observed devia-tion from these suggested measures would down-grade the seismic resistance capacity of theelements under investigation, and a further evalu-ation and/or a remedial action should be taken.

e. Rapid analysis. A minimum of engineeringcalculations, on the basis of approximate elementweights and earthquake response accelerations,may be required to supplement the qualitativeevaluation procedure. The force and deformationcriteria will be in accordance with the provisionsof the BDM and/or SDG.

9-5. Detailed evaluationThe elements and their anchorages that have beenidentified in the qualitative evaluation procedureto be susceptible to damage will be subjected to adetailed evaluation. The nonstructural elementsand their anchorages will be checked to resistforces and deformations caused by earthquakemotions prescribed for buildings in this manual.The effect of nonstructural elements on the per-formance of the building will also be considered.Either a dynamic approach prescribed in SDG,chapter 6, or a static approach prescribed in BDM,chapters 9 and 10, may be used, except whenauthorized the dynamic approach will be used inthe evaluation of essential systems.

9-6. Representative upgrading tech-niques

Since structural quality and anchorage of non-structural elements in existing buildings varygreatly, it is not feasible to present methods ofstrengthening all such elements in detail, espe-cially for mechanical and electrical elementswhere there are many different types and models.Such equipment is usually designed and installedby manufacturers without consideration of seismicresistance. Care and engineering judgment shouldbe exercised for determining the best feasiblemethods of upgrading. Economic feasibility mustbe weighted against seismic risk in strengtheningnonstructural elements, as should be done forbuildings as a whole. For example, loss of files,computer facilities, or communication systems in amedical facility can shut down the system. Somegeneral upgrading measures are outlined in thisparagraph.

a. Architectural elements.(1) Exterior walls, parapets, appendages, ve.

neers, etc.(a) Reduce height of parapet or brace to the

roof structural system, as necessary.(b) Anchor appendages, veneers, and other

potential falling objects or replace their anchor-ages, as needed.

(c) Refer to BDM, figure 9-2, for design ofexterior precast elements.

(2) Interior walls and partitions.(a) Remove clay-tile partitions.(b) Provide lateral bracing for partitions.(c) Separate partitions from structural ele-

ments with sufficient joints coordinated with antic-ipated interstory drifts.

(d) Refer to BDM, figure 9-1, for typicaldetails of interior walls and partitions.

(3) Ceilings: Suspended system and surfaced-applied system.

9-2

RM 5-809-10-2INAVFAC P-355.2/AFM 88-3, Chop 13, Sec BTable 9-1. Guidelines for evaluating seismic performance of selected nonstructural elements. (Sheet I of 4)

System/Element Potential Types of Damage

Architectural

Appendages:

Exterior P/C panels Failure of connections due toprying action; bolts pull out.

Parapets Cracks due to cantilever action.

Ornaments, veneers Failure of anchorage.

Partitions:

Permanent-masonry, tile,metal stud, gypsumboard, plaster

Demountable-metal, wood,metal/glass

Damage occurs in the anchorage tothe supporting structure and in thecracking of brittle surfaces.

Separation at top/bottom channels,overturning and compression failure,glass cracking.

Ceiling:

Exposed tee bars andluminous systems

Tees deform or pulled away from thewall support; breakage of hangers.

Concealed spline system

Gypsum board with tiles,plaster

Wood joists with nail ortiles

Damage occurs at perimeter wallswhere supports bend and tilestear and fall.

Gypsum boards drop and loosen tilesat perimeter walls.

Most earthquake resistant of allceiling types.

Lighting Fixtures:

Recessed Separation of fixtures due to rackingof suspended ceilings.

Surface mounted Generally undamaged by earthquakes.

Sheet 1 of 4

9-3

RM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec BTable 9-1. Guidelines for evaluating seismic performance of selected nonstructural elements. (Sheet 2 of 4)


Pendant Very susceptible to damage; failuresat ceiling connections, in swiveljoints, at fixture housings, insupporting stems or chains. Damageto suspended ceiling.

Building Contents:

Shelving, cabinets,storage racks

Computer equipment

Overturning, dislodging of storeditems.

Top-heavy tape transports fall over;impact damage caused by equipmenthitting walls or other equipment.

2. Mechanical

Rigidly MountedEquipment:

Equipment

Tanks

Equipment withVibration Isolators:

Equipment without anchors causesecondary damage on connected ipesand electrical service connections.

Unanchored tanks tip over, legs andsupport brackets collapse; secondarydamage to connecting piping.

More susceptible to damage than fixedmounted equipment; failure ofisolators causes equipment to falland damage to connecting piping andelectrical service connections.

Piping: Failures at elbows and bents due toexcessive movement; screwed fittingsare more vulnerable to damage thanwelded or brazed fittings; failuresat building seismic joints due todifferential movements; failure ofhanger assembly.

Sheet 2 of 4

9-4

RM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec BTable 9-1. Guidelines for evaluating seismic performance of selected nonstructural elements. (Sheet 3 of 4)


Ducts, Diffusers, etc.: Long runs of large ducts fail as aresult of excessive motion by theearthquake; large diffusers drop fromceilings where they lack propersupport.

3. Other Essential Svstems

Elevators: Traction

Counterweight guidesystems

Cabs guide systems

Motor generator sets

Control panels

Control relays

Elevators: Hydraulic

Counterweights derail, allowingthem to swing.

Out of alignment.

Thrown off their unanchored isolationmounts.

Topple over where not anchored tostructural frame.

Damaged when unlatched and hingedpanels thrown open.

No specific experience on observeddamage.

Emergency Power System:

Transformers

Switchgears

Motor and generators

Inadequately secured transformersfall from pedestals, causing majordamage to bushings, radiators,internal parts, and interconnectingbus; pole transformers are morevulnerable to damage than pedestal-mounted.

Motion of unsecured switchgearsdamage connections to the equipment.

Vibration isolators shear off;damage power, fuel, and cooling lineconnections.

Sheet 3 of 4

9-5

RM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chop 13, Sec BTable 9-1. Guidelines for evaluating seismic performance of selected nonstructural elements (Sheet 4 of 4)


Battery racks

Panel boards

Fuel storage tanks

Generally remain in place whenstrapped to walls.

Overturning of unsecured tall units;rigid conduit failure due to supportfailure.

Fracture of pipe connections due toexcessive movement of unanchoredsupport.

Fire Protection System:

Sprinkler and stand pipes

Pumps and tanks

Steel stairs

Concrete stairs

Doors and frames

Corridors

Only minor damage has been observed.

Fracture of pipe connections due toexcessive movement of unanchoredsupport.

Yielding of welded connections.

Shear cracking if tied to thestructure.

Doors deform and jam; frames warp.

Corridors blocked with debris.

Hazardous Materials:

Storage tanks, bottles,cylinders, and pipescontaining hazardoustoxic materials

Expose chemicals due to rupture ofcontainers; damage caused byexcessive movement or failure ofadjacent elements.

Communications:

Intercom/PA system,telephone equipment,and switchboards

Loss of communications due to brokenwires.

Sheet 4 of 4

9-6

RM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sc B

(a) Brace ceiling grid at regular intervalsagainst lateral and vertical movements.

(b) Fasten cross runners to the main run-ners with locking clips to prevent cross tees frompulling or twisting out of the main runners.

(c) Brace ductwork and piping systems inthe ceiling space against lateral and vertical move-ments.

(d) Positively connect all elements together.(e) Reinforce gypsum board ceiling at nail

points, using large-head nails or steel nailingstrip.

() Refer to BDM, figure 9-3, for recom-mended suspended ceiling system.

(4) Lighting fixtures: Recessed fixtures, surface-mounted fixtures, and pendant fixtures.

(a) Secure recessed fixtures directly to themain runners of the ceiling system.

(b) Provide recessed fixtures with indepen-dent secondary supports attached to the fixturehousing and the building structures.

(c) Attach surface-mounted fixtures directlyto the building structure and suspended ceilingsystem using positive locking devices.

(d) Separate pendant fixtures sufficiently sothat sway arcs do not intersect.

(e) Provide sway bracing if swinging clear-ance of chain-hung fixture is not adequate.

(t) Refer to BDM, paragraph 10-6, for thedesign requirements of lighting fixtures and sup-ports.

(5) Building contents: Shelving, storage racks,filing cabinets, computer equipment, etc.

(a) Anchor all storage racks at base andlaterally brace at top or attach to walls.

(b) Provide safety bars for open shelvingwhere practical.

(c) Brace computer floors and provide drop-in panels detailed to prevent displacement duringan earthquake.

b. Mechanical systems:(1) Mechanical equipment:

(a) Anchor all floor-mounted equipment tothe structural slab.

(b) Provide isolation restraints for all hungequipment.

(c) Remove vibration isolators and boltequipment to floor slab or add snubbers to limitexcessive movement.

(2) Distribution system: Pipes, ducts, and con-duit.

(a) Provide sway bracing in both longitudi-nal and transverse directions on all pipes 2%inches or larger, based on intervals recommendedin BDM, figures 104 to 10-7. Also refer to BDM,figure 10-8, for acceptable details of sway bracing.

(b) Provide flexible joints where pipes enter

building, where rigidly supported pipes connect toequipment with vibration isolation, and whereneeded to accommodate large interstory drifts forlarge pipe risers rigidly mounted between floors.Refer to seismic details in BDM, figure 10-9.

(c) Provide pipe sleeves through walls orfloors large enough to allow for relative move-ments.

(d) Provide sway bracing in both longitudi-nal and transverse directions on all ducts with aperimeter greater than 120 inches and for allducts in boiler and equipment rooms.

(e) Diffusers, registers, and grillers shouldbe positively attached to the ductwork.

(j) Positively tie flexible ducts to the ceiling,wall, or floor system.

c. Essential systems that are not covered above.(1) Elevators: Traction and hydraulic types.

(a) Install additional rail support bracketsand brace spreader beams (counterweight).

(b) Install safety shoes on roller guide.(c) Strengthen the car guide rails on long

spans by installing spacers between the back-to-back rails at midpoints between the spreaderbeams.

(d) Protect traveling cables to prevent themfrom being twisted and snarled or from jumpingout of their sheaves or guides.

(e) Design more rigid structural framesaround hoistways and door frames that can accom-modate the anticipated interstory drifts.

() Anchor motor generators and control cab-inets or provide restraints on vibration isolatorsunder generators to prevent excessive movement.

(g) Install emergency stop gear.(h) Refer to BDM, figure 10-13, for details

of traction-type elevator.(2) Emergency power system.

(a) Anchor or restrain transformers, switch-gear, and control panels.

(b) Bolt generator directly to foundation.(c) Brace cooling tower or install an auxil-

iary cooling system such as generator radiatorsystem at grade level.

(d) Anchor fuel storage tank and install flexloops in fuel lines between the tank and thebuilding and at the connection to the generator.

(e) Strap all batteries on racks; anchor andbrace storage racks.

(3) Fire protection system.(a) Install mounting brackets for hung and

free-standing fire extinguishers.(b) Brace standpipes.(c) Brace the sprinkler system piping in

accordance with NFPA No. 13 (refer to BDM,paragraph 10-7); fire pumps should be governedby NFPA No. 20.

9-7

RM 5-809-10-2INAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

(d) Provide slip joints at the top or bottomof each flight of stairs.

(e) Ensure that exitways will not becomeblocked after an earthquake.

(4) Protection against hazardous materials.(a) Install seismic-activated shut-off valves

at appropriate locations on supply lines for naturalgas and other hazardous materials.

(b) Brace fuel lines, bottles of laboratorychemicals, lead storage safes for radioactive mate-

rials, liquid oxygen storage tanks, and similarcontainers and protect them from damage causedby movement or failure of adjacent elements.

(5) Communications.

(a) Secure and anchor emergency comunica-tion equipment or relocate in a nonvulnerableportion of the facility, preferably the lower levels.

(b) Provide alternate internal and externalcommunication systems.

9-8


APPENDIX A

SYMBOLS AND NOTATIONS

BDM = Basic Design ManualCb = base shear coefficient. Equivalent to ZIKCS coefficient in BDM, equation 3-1D or DL = dead loadDMRSF = ductile moment resistant space frame as defined in BDM chapter 3dN = lateral displacement at level NE or EQ = earthquake loadEQ-I = earthquake that has a 50-percent probability of being exceeded in 50 yearsEQ-Il = earthquake that has a 10-percent probability of being exceeded in 100 yearsg = acceleration due to gravityL or LL = live loadL/r or l/r = ratio of length (L or 1) to radius of gyration (r)N = number of stories above the base to level nn = the level that is uppermost in the main portion of the structure (generally the roof)PFN = modal roof participation factor shown in table 4-1 (Refer to SDG 4-1)PGA = peak ground accelerationRSAP = Rapid Seismic Analysis Procedure summarized in appendix DRSS = root-sum-squares, same as SRSSS. = response spectrum value for spectral acceleration, as a ratio of the acceleration of gravity (g)Sd = response spectrum value for spectral displacementS, = response spectrum value for spectral velocitySDG = Seismic Design GuidelinesSRSS = square-root-of-the-sum-of-the-squaresS1,S2,S3 = soil types for developing ATC-3-06 response spectra (NBS 510)t = time in secondsT = fundamental period of vibration of the structureTa = period of vibration of equipment or architectural appendageV = total lateral forceW = weight of a system or buildingWP = weight of a portion of a structure, equipment, or architectural appendageWX = weight at or assigned to level xct = modal base shear participation ratio for fundamental mode as shown in table 4-1 (Refer to

SDG eq 4-2)6N = same as dN

A-1

TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chop 13, Sac B

APPENDIX B

REFERENCES

B-1. Government Publications.a. Department of the Army.

TM 5-838-2 Army Health Facility Designb. Department of the Navy.

T.M. No. 51-78-02 Rapid Seismic Analysis Procedure Naval Civil Engineering Labo-ratory

T.M. No. 51-83-07 Modification for Enhancing the Rapid Seismic Analysis ProcedureNaval Civil Engineering Laboratory

c. Departments of the Army, Navy, and Air Force.TM 5-809-1O/NAVFAC Seismic Design for Buildings (BDM)

P-355/AFM 88-3, Chapter 13TM 5-809-10-1/NAVFAC Seismic Design Guidelines for Essential Buildings (SDG)

P-355.1/AFM 88-3, Chapter13, Sec A

d. National Bureau of Standards (NBS).National Technical Information Service, 5285 Port Royal Road, Springfield, VA, 22161orSuperintendent of Documents, U.S. Government Printing Office, Washington, DC, 20402Special Publication 510 (514 pages), Tentative Provisions for the Development of Seismic Regulations

for Buildings (ATC-3-06), 1978Evaluation of Strength of Existing Masonry Walls for the Veterans Administration

B-2. Nongovernment Publications.American Concrete Institute (ACI), Box 19150, Redford Station, Detroit, MI, 48219ACI 318-83, Building Code Requirements for Reinforced ConcreteAmerican Institute of Steel Construction (AISC), 400 N. Michigan Ave., 8th Floor, Chicago, IL, 60611Specification for the Design, Fabrication, and Erection of Structural Steel for Buildings, November 1,

1978, with CommentaryAmerican Society for Testing and Materials (ASTM), 1916 Race Street, Philadelphia, PA, 19103ASTM StandardsInternational Conference of Building Officials, 5360 South Workman Mill Road, Whittier, CA, 90601Uniform Building Code (BC), 1985

B-1

APPENDIX C

STATIC CODE PROCEDURE

C-1. IntroductionThis appendix prescribes the static code procedurefor seismic evaluation analysis and upgrading/strengthening rquirements for existing buildingsin low or moderate seismic regions. The static codeprovisions in TM 5-809-10/NAVFAC P-355/AFM88-3, Chapter 13, Seismic Design for Buildings(BDM), are the basis for this procedure. Themethodology for this procedure is indicated infigure C-1. This static code procedure will beperformed on a project-by-project basis for seismiczone 1 and for nonessential buildings in seismiczones 2 and 3 as determined by approving author-ity.

C-2. Applicability of the static codeprocedure

Since the early 1970s, the static seismic provisionsof the BDM have been utilized for the evaluationand upgrading of existing military buildings on aproject-by-project basis. The static code proceduredescribed in this appendix was used for the evalua-tion and seismic upgrading of buildings in seismiczone 1 and nonessential buildings in seismic zones2 and 3. At the discretion of the approving author-ity, the procedure may also be used for selectedhigh risk and essential buildings (importance fac-tors I = 1.25 and 1.50) and also for buildings inhigher seismic zones. The implementation of thisprocedure will be as authorized by the approvingauthority.

C-3. Preliminary structural evaluationThe purpose of the evaluation is to determine ifthe building is in compliance with the acceptancecriteria; to identify any structural deficiencies; andto provide the basis for strengthening or upgrad-ing. .The preliminary evaluation will be made onthe basis of structural analyses performed in ac-cordance with the prescribed seismic forces andallowable stresses of the BDM.

a Document review. The available "as built"drawings, design calculations, specifications, andother design documents obtained from the usingagency will be reviewed by the engineer to iden-tify the lateral force resisting system and otherpertinent information. This initial study will com-pare wind lateral loads to seismic lateral loads onthe structure. If the design wind load on theexisting structure governs over the seismic load,no further investigation will be required, unlesswarranted by the irregular configuration andlorother characteristics of the building. If the seismicload governs, the data will be documented (i.e., the

lateral load force resisting system) for the siteinspection. Also, supplementary notes and/orsketches will be made of the lateral force resistingsystem, as necessary, to be confirmed by the siteinspection.

b. Site inspection. A field examination of thebuilding will be performed and the following obser-vations will be noted for use in the structuralevaluation and design of the seismic strengtheningor upgrading.

(1) Confirm the structural data indicated onthe drawings; particularly with respect to thelateral force resisting system. Note any structuraladditions or modifications not indicated on thedrawings.

(2) Determine the general condition of thestructural elements (e.g., corrosion of structuralsteel, shear cracks in concrete or masonry, andsplitting or checking of timber). Note also anydamaged or missing members or other deviationsfrom the drawings.

(3) Establish the various load paths by whichlateral forces are transferred from the roof or floorsystems to the vertical resisting elements (i.e.,frames or walls) and to the foundations. Note anydiscontinuities in the load paths, redundant pathsor backup systems and the adequacy of support oranchorage of concrete and masonry walls, at eachfloor or roof level, for out-of-plane forces.

(4) Note extent and details of anchorage and/or bracing of architectural elements (i.e., parti-tions, suspended ceilings, curtain walls, parapets,and canopies) and mechanical and electrical equip-ment (i.e., emergency motor generators andpumps, boilers, cooling towers, critical piping,light fixtures).

c. Acceptance criteria. The basic acceptance cri-teria for the seismic resistance of existing build-ings is based on the provisions of the BDM.However, if an existing building does not conformto the basic criteria, some tolerances are providedin the following paragraphs in recognition thatseismic upgrading is an expensive and disruptiveprocess and it may be cost-effective to accept anexisting building that is marginally deficientrather than to enforce strict adherence to thecriteria.

(1) Conforming systems and materials. Whenthe lateral force resisting structural systems andmaterials are in compliance with the requirementsof the BDM (Refer to BDM paragraph 3-6 forapproved structural systems and to BDM chapters3, , 6, 7, and 8 for material requirements), theearthquake demand represented by the lateral

C-1

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop. 13, Sec B

I Authorizedbuilding.

IPreliminary structural

evaluation(para C-3)

,Compliance with

acceptance criteria(para C-3a)

I

r r

I Complies -upgrading not

required

Does notcomply

IDevelop upgrading

concepts(para C-4a)

Other considerations(para C-4b) -

Acceptance criteria(para C-4a)

Upgrade nonstructuralelements(para C-4d)

Concept submittal(para C-4e)

I Final design andI preparation of II contract documentsI (pars C-5) IL _ - - __ _-

Figure C-1. Methodology for static code procedure

forces prescribed in paragraph 3-3 of the BDMmay be reduced by a maximum of 20 percent (i.e.,to 0.80 of the prescribed force) but the driftlimitations will remain as prescribed in paragraph3-3(H) of the BDM. This is the minimum accept-able level of safety for long-term (more than 5years) use. If it is not feasible to meet thisrequirement, plans should be made to phase out

C-2

the structure.(2) Nonconforming systems and materials.

When the lateral force resisting system or thestructural materials do not conform to the ap-proved systems and material specifications of theBDM, justification for acceptability of the existingsystems and/or materials is required. Require-ments for substantiated data are prescribed below.

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap. 13, Sec B

Acceptance of the approval agency is also required.(a) Structural systems not specified in the

BDM (e.g., "nonductile" moment resistance rein-forced concrete frames and unreinforced masonryshear walls) require an analytical evaluation re-port. The report will include data for establishingthe capacity of the system to resist seismic loadsand justification for the performance of the systemsatisfying the intent of the BDM provisions.

(b) Structural materials not satisfying theminimum requirements of the BDM require anevaluation report. Guidelines for evaluation ofexisting materials are provided in appendix E.

(c) The acceptance criteria for the substanti-ated noncomplying structural systems and materi-als are the same as prescribed in paragraph (1),above, except that the drift limitations will bereduced to 80 percent of those prescribed forconforming systems and materials.

d. Methodology for the evaluation. The struc-tural analysis will consist in the application of theprescribed seismic forces to the lateral-force-resisting system of the building in the samemanner as for new construction.

(1) In older existing buildings, particularlythose not specifically designed for seismic forces,in addition to investigation of the primary struc-tural elements (i.e., shear walls, frames, bracing),attention will be paid to the investigation ofpossible deficiencies in the design of floor and roofdiaphragms, including necessary chords, dragstruts, shear transfer to vertical resisting ele-ments, and support or anchorage of concrete andmasonry walls for out-of-plane forces (see chapter 5of the BDM). The resulting stresses in the variousstructural elements will be combined with thedead and live load stresses as prescribed in theBDM and compared with the allowable stresses.Structural elements that are found to be over-stressed will be evaluated as to their importanceto the stability or integrity of the structure. Forexample, moderate overstress in flexural membersof redundant systems (e.g., ductile steel or concreteframes) may not lead directly to structural failureuntil other mechanisms occur (e.g., buckling, P-delta instability, or shear failure). In a similarmanner, shear overstress in a minor shear resist-ing element of a concrete building may not be ofserious consequence if other shear resisting ele-ments are available to resist the redistributedforces from the overstressed element.

(2) For an existing building with identifieddeficiencies (e.g., overstress in a primary shearwall, diaphragm, column, or brace), an overstressratio will be calculated. This value is defined asthe ratio of the calculated stress in the mostoverstressed primary structural elements to the

allowable stress prescribed by the BDM for thatelement. The base shear capacity of these build-ings shall be calculated by dividing the designbase shear (i.e., the base shear from the BDMprovisions as used in the evaluation) by the over-stress ratio.

e. Report. A report will be prepared to summa-rize the results of the preliminary evaluation. Thereport will include the following items.

(1) Basic design data; i.e., design loads andproperties of materials.

(2) Description of preliminary evaluation pro-cess.

(3) Method of analysis for each structuraltype.

(4) Description of each building analyzed in-cluding lateral force resisting system, assumedstructural properties, etc.

(5) Design calculation with results of analy-ses, i.e., overstress ratios, and base shear capaci-ties including a conclusion on the acceptance ofthe existing structure.

(6) Recommended upgrading design conceptsand preliminary cost estimates.

C-4. Development of design conceptsBased on the results of the preliminary evaluationand the identified deficiencies with respect to theacceptance criteria of the various structural ele-ments or systems, three alternative upgradingdesign concepts will be developed unless it isobvious that only one concept can be economicallyjustified.

a. Acceptance criteria The minimum design cri-teria for the development of concepts for seismicupgrading of existing buildings will be substan-tially in accordance with the applicable provisionsof the BDM as required for new construction (exactcompliance with all details is not required). Non-conforming structural systems or materials (e.g.,unreinforced masonry and nonductile reinforcedconcrete frames) may be retained in the upgradingconcept provided an evaluation analysis is submit-ted to demonstrate that the nonconforming ele-ments are precluded from collapse and do notconstitute a hazard to life safety when subjected tothe BDM forces and deformations.

b. Other considerations. In addition to compli-ance with the acceptance criteria, the developmentof alternative concepts for seismic upgrading willaddress the general considerations prescribed inparagraph 6-3a of this manual. It will be recog-nized that it may not be feasible and/or costeffective to completely satisfy all of these consider-ations in the strengthening or upgrading of anexisting building. However, in many cases, theengineer has the option of designing the structural

C-3

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap. 13, Sc B

modifications at little or no additional cost and thebuilding is not only made stronger, but its re-sponse is also improved by reduction of torsionaleccentricity or other undesirable characteristics.

c. Strengthening techniques and options. Gener-ally, the strengthening options are simple andobvious (e.g., a braced steel frame building mayneed heavier or additional bracing or a concreteflat slab building may be strengthened with newshear walls with minimal impairment of the build.ing function); however, in larger and more complexbuildings (e.g., hospitals), the most cost effectivesolution may require detailed studies. All feasibleoptions should be considered schematically and thethree best alternatives selected for concept devel-opment. Chapter 6 of this manual presents repre-sentative strengthening techniques and options forvarious structural systems. Combinations or varia-tions of these options may be developed to suitspecific buildings.

d Upgrading of nonstructural elements. Evalua-tion of the adequacy of supports, anchorages, orbracing of nonstructural elements will be per-formed for compliance with the requirements ofchapters 9 and 10 of the BDM.

e. Concept submittal A concept submittal willbe prepared for review and approval by the ap-proval authority. The submittal will comply withagency standards. The design effort represented ina concept submittal will generally represent 25 to35 percent of the effort required to complete thedesign of normal projects, but this figure could behigher for structural modifications. The conceptsubmittal will include the following elements:

(1) Basis for design. This will include theacceptance and design criteria; a summary descrip-tion of the decifiencies identified in the structuralanalysis; a narrative description of the alternativeupgrading concepts; and justification for the rec-ommended concept including construction phasingwhen appropriate.

(2) Concept drawings. Drawings and/orsketches will be prepared to illustrate the recom-mended concept. The drawings must be adequateto describe the nature, extent, and location of workrequired and, as a minimum, will include founda-tion and framing plans, typical sections, and typi-cal connection details.

(3) Calculations. Edited, checked, and indexedcalculations will be included in the submittal tosupport the design of upgrading modifications.

(4) Outline specifications. Outline specifica-tions will be prepared to describe the type andgrade of structural material and procedures byreference to standard or industry specifications.

(5) Cost estimates. The concept submittal willinclude construction cost estimates for the alterna-tive concepts as well as the recommended concept.These estimates shall be sufficiently accurate anddetailed for budgeting and programming.

C-5. Final design and preparation ofcontract documents

Upon authorization of the approval authority, thefinal design of the approved concept will be imple-mented and the necessary project constructiondocuments will be prepared in accordance with therequirements of the BDM.

a. Final design. The final design will be done onthe basis of the results from the structural analy-sis and the development of design concepts asdirected by the approval authority. The final de-sign will include a complete analysis of the up-graded structure, completed drawings of all detailsfor the project, and a detailed cost estimate. Thefinal documents will be complete in themselves,without the need to refer to the previous analysisand development work.

b. Preparation of project documents.(1) Design analysis. A design analysis, con-

forming to agency standards, will be provided withfinal plans. This analysis will include seismicdesign computations for the determination ofearthquake forces on the building, for the struc-tural evaluation of the existing building, and forthe upgrading of the existing structure, includingstresses in the lateral-force-resisting elements andtheir connections, and the resulting lateral deflec-tions and interstory drifts. The first portion of thedesign analysis, called the Basis of Design, willcontain assumptions made with regard to selectionof dead, live, and seismic loads; allowable stressesfor all original and new structural material; de-scription of the existing structural system and thestructural system selected for upgrading the build-ing to resist lateral forces; and a discussion of thereasons for its selection. If irregular conditionsexist, a statement describing special analyticalprocedures to account for the irregularities will besubmitted for review and approval by the approvalauthority. The Basis of Design will also indicateany possible future expansion for which provisionsare made.

(2) Drawings. Preparation of drawings willconform to agency standard.

(3) Specifications. Preparation of specificationswill conform to agency standards for ordinaryconstruction with additional specific requirementsthat relate to seismic construction and to upgrad-ing of existing construction.

C-4

TM 5-809-10-2/NA VFAC P-355.2/AFM 88-3, Chap. 13, Sc B

APPENDIX D

SUMMARY OF THE RAPID SEISMIC ANALYSIS PROCEDURE

D-1. IntroductionThis appendix summarizes the rapid seismic anal-ysis procedure (RSAP) developed by the NavalCivil Engineering Laboratory (NCEL) for the Na-val Facilities Engineering Command (NAVFA-CENGCOM). The RSAP is preceded by computerand on-site screening at which time site hazardsare identified. The RSAP is intended to identifybuildings that are either liable to be severelydamaged or only lightly damaged. It is a furtherscreening tool. A complete description of thisprocedure is given in the NCEL Technical Memo-randums TM No. 51-78-02 and TM No. 51-83-07.Examples showing the analysis of a steel and aconcrete building are given in paragraph D-9.

D-2. BackgroundThe RSAP was initially developed by John A.Blume & Associates in a pilot study of a relativelylarge number of buildings at Puget Sound NavalShipyard in 1973. The procedure was formalizedby NCEL.

a. Seismic investigation of an activity. The seis-mic investigation is divided into two phases. InPhase I the selected buildings at the activity areanalyzed approximately by RSAP. Phase I paral-lels chapters 2, 3, and 4 of this manual. Thosebuildings found to be inadequate to Phase I areanalyzed in detail in Phase I to determine thedegree of strengthening required and to estimatecosts of upgrading. Phase II parallels chapters 5, 6,and 7 of this manual.

b. RSAP. The main purpose of the RSAP is toidentify those buildings that may be susceptible tosevere damage. The major steps of the RSAP areshown in table D-1. The procedure has the samedevelopment roots as the procedures covered bychapters 2, 3, and 4 of this manual. The majormodifications that NCEL made to the basic rapidanalysis procedure follow:

(1) Systemization of the analysis of the facilityinventory assets at a Naval installation.

(2) Development of the response spectra forthe design earthquakes. This procedure has sincebeen formalized by the Tri Services Committeeand is covered by NAVFAC P-355.1 (e.g., SDG).

(3) Automation of computation of shear stiff-nesses for concrete or masonry buildings, the firstmode shape and natural period of multi-storybuildings, and estimation of building damage fromthe response spectra.

(4) Enhance the RSAP with the followingmodifications:

(a) Criteria for field screening.(b) Criteria for eliminating buildings from

further investigation in the rapid analysis.(c) Modified criteria for determining struc-

tural properties including damping values, naturalperiods and base shear capacities.

(d) Modified criteria for determining thesite demand from the response spectra at theultimate base shear capacity for certain systems.

(e) Criteria to aid the selection of buildingsfor detailed analysis.

(f) Criteria to aid in evaluating the ade-quacy of the lifeline utilities at a given Navalactivity.

D-3. Selection of buildingsThe selection procedures of the RSAP includesprovisions for inventory reduction, field screening,gathering of structural drawings and calculations,a visual inspection of the selection buildings, anda cursory survey of the site geological hazards.

a. Inventory reduction. A procedure and criteriaare presented in the RSAP references to facilitatethe selection of the buildings for the visual screen-ing. With the issue of this manual, the RSAPcriteria are superseded by the screening procedureof paragraph 2-3 of this manual.

b. Field screening. The RSAP references recom-mend criteria for eliminating buildings from fur-ther investigation. These decisions are made afterthe brief survey to determine physical conditionsand after a brief examination of constructiondrawings. The criteria are similar to those pro-vided in paragraph 3-2 of this manual.

c. Visual inspection of selecting buildings. Afinal visit is made to verify that buildings arebuilt as shown on the drawings, especially thelateral-force resisting elements. This step of theRSAP is similar to the first two steps of thepreliminary evaluation described in paragraphs4-2a and 4-2b of this manual.

d Site geological hazards During the site visits,a cursory survey should be made of the potentialseismically-induced geological hazards based onthe available geologic subsurface information.These hazards include faults and fault rupture,liquefaction, landslide and lateral spreading,ground cracking, compaction settlement, tsunami,and seiches.

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap. 13, Sec BTable D-1. Major step# of the Rapid Seismic Analysis Procedure (RSAP)

Pre l iminary

o Visual survey of the lifeline utility system.

o Screening.

o Selection of buildings.

RSAP

o Determination of the site elastic response spectra.

o Determination of the structural properties at yield andultimate levels for the transverse and longitudinaldirections.

o Estimation of damage from the structural capacities anddemands from the response spectra.

Follow-Up

o -Selection of buildings for detailed analysis.

o Follow-up investigation of site hazards.

D-4. Determination of response spectraSite specific elastic response spectra for singledegree-of-freedom systems are determined in ac-cordance with the procedures given in the SDG,chapter 3, appendix C and appendix D. The NAVFAC ground motion criterion for the RSAP is amaximum ground acceleration having a 20 percentprobability of exceedence in 50 years. (Note, thisdiffers from the provisions in this manual, whichspecifies EQ-fl. EQ-U has a 10 percent probabilityof not being exceeded in 100 years.)

.a. Sample response spectra. Figure D-1 showsthe resulting response spectra for an intermediatesoil site with a maximum ground acceleration of0.25g. The curves in the figure are used fordetermining the seismic demands (loading) on thebuildings. These spectra are used for the examplesof the RSAP given in paragraph D-9.

b. Acceptable capacities. Buildings with spectraacceleration capacities at ultimate that satisfy thesite demands at ultimate according to the groundmotion criterion are considered fully acceptable.Those buildings whose spectral acceleration capac-ities at ultimate are 75 percent of the demands atultimate are considered marginal.

c. Variation in force levels. It is recommendedthat damage estimates be made for a few forcelevels below and above the 80 percent/50 yearlevel. These estimates provide a profile of the

expected seismic response of the building. Thisrecommendation is similar to those in paragraph4-2d(6) of this manual.

D-5. Determination of structural prop-erties at yield and ultimate evels

The damping values, the natural periods, and thebase shear capacities are determined for the trans-verse and longitudinal directions of the building.

a. Damping values. The assumed damping val-ues used in the RSAP are given in table D-2.

Table D-2. Damping values

Percent of CriticalYield UltimateType

Steel

Concrete

Wood

Masonry

5 10

5 10

10 20

5 10

D-2

TM 5-809-1O-2/NAVFAC P-355.2/AFMS 88-3, Cheap. 13, Sec B

. O~~~~~~~~~~~.

, . {- ' {11 r hi~~~~~~~~~~~~~~~~~5

10

00ri -0 O

(gil) S OlT21.I010 tjura4^s

D-3

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap. 13, Sec B(Note, these vary from the values given in table4-2 of this manual.) The damping value increasesfrom the yield to the ultimate level due to theinelastic deformation of the structural and non-structural elements of the building.

b. Natural periods. Natural periods of the build-ing in the transverse and longitudinal directionsare determined from the following equations:

(1) Yield Level:

mated by assuming unit weights for the roofframing, floor framing, wall, actual live loads (ifany), and other miscellaneous items.

(5) The natural periods of the building at theultimate level, Tu, are computed from the periodsat the yield level, Ty, by using equation D-4. Therange of the recommended ductility factors, u, aregiven in table D-3.

Table D-3. Ductility factors0.05 Empirical: T = C . b

Theoretical: T = 2 x t

n k

E wiei=l

Ty= 2 n

g ;5Pi=l

(eq D-1) Type i

(eq D-2)

Steel 4-6

(eq D-3) Concrete 3-4

Wood 3-4(2) Ultimate

a\/ - (eq D-4)

aUwhere h,, = height of building (ft)

D = width of building in the directionconsidered (ft)

C = a constant between 0.75 and 1.5 toaccount for building mass and stiff-ness

m = seismic massk = stiffness of the building in the direc-

tion consideredw = weight of the building at level "i"A = elastic deformation at level "i" us-

ing the applied lateral forces fjf = approximate lateral force distribu-

tion consistent with the assumedfundamental mode shape

p = ductility factor equal to ratio ofmaximum displacement to yield dis-placement

Soy = spectral acceleration capacity of thebuilding at yield level

S;.u = spectral acceleration capacity of thebuilding at ultimate level

(3) Equation D-1 is obtained by multiplyingequation 3-3A of NAVFAC P-355 (e.g., BDM) bythe constant C to account for the different buildingmasses and stiffnesses. Equation D-2 is the natu-ral period for a single degree-of-freedom system.

(4) Equation D-3 is the Rayleigh equation 3-3of the BDM. The weight of the building is approxi.

Masonry 2-3

c. Base shear capacities. After reviewing thefield survey notes and the construction drawings,rought sketches of typical plans and elevations ofeach building are made to determine the primarylateral-force resisting system or systems. The yieldand ultimate base shear capacities of a buildingare computed by summing the contributions fromthe vertical lateral force-resisting elements of thebuilding in the transverse and longitudinal direc-tions and dividing the results by the seismicweight of the building. The horizontal lateral-forceresisting elements such as beam, girders, floor androof diaphragms are only considered indirectly inthe analysis by examining the effectiveness oftheir connections to the vertical lateral-force re-sisting elements.

(1) Yield capacity. The yield capacity of abuilding is defined as the lateral-force required tocause the significant yielding of the most critical,not necessarily the most rigid, component of thelateral-force resisting system.

(2) Ultimate capacity. The ultimate capacity ofa building is defined as the lateral-force requiredto cause yield initiation of the most flexible compo-nent of the lateral-force resisting system of theformation of a collapse mechanism.

(3) Examples.(a) A steel building with a lateral-force re-

sisting system consisting of infill brick walls andX-braces may behave as follows in resisting seis-mic forces. The brick wall and X-braces may act

D-4

TM 5-809-10-2INAVFAC P-355.2/AFM 88-3, Chap. 13, Sec B

together in resisting the seismic forces until crack-ing of the brick wall is initiated. Then the X-bracing and columns (only after the yielding of theX-braces) will take more and more of the seismicloading until they fail.

(b) For a reinforced concrete building withshear walls, the shear walls will resist most of theseismic loading until they have started to crack.Thereafter, the frames will start to resist onincreasing portion of the loading. For reinforcedconcrete frame and/or shear wall and reinforcedmasonry buildings, the ultimate base shear capac-ity, CBu, is computed first. Then, the yield baseshear capacity, CBY, is obtained by dividing CEUby a load factor 1.5.

(c) Wooden frame buildings with shear pan-els will behave like the concrete frame and shearwall buildings.

d. Spectral acceleration capacities.(1) Before they can be used for estimating the

earthquake damage, the base shear capacities CBYand CBu must be transformed to the spectralacceleration capacities S and S using thefollowing equations:

s = a CEY (eq D-5)S = a CTBU (eq D-6)(2) The constant a in the equations depends

on the mode shape and mass distribution. Thegreat majority of the Navy buildings are less thanthree stories high and can be classified as low-rise(S 6-story). The a constant for low-rise buildingsranges between 1.05 and 1.18, with the largervalue for the taller buildings. For conservatismand simplicity, a is assumed to be one in mostcases. (Note, a as used in this appendix is theinverse of a used in the SDG and in table 4-1 ofthis manual.)

D-6. Estimate of damageEarthquake damage is estimated from the de-mands of the response spectra using the dampingvalues, natural periods, and spectral accelerationcapacities of the building.

a. Damage assumption. Until yield capacity ofthe building is reached, damage is assumed to beequal to zero and ductility factor equal to one.When the ultimate capacity is reached, damage isassumed to be equal to 100 percent and ductilityfactor equal to the maximum value. For intermedi-ate values of capacity, damage assessment is nec-essarily somewhat subjective and depends onmany factors not amenable to analytical treat-ment. For the rapid analysis, damage is assumedto vary linearly between the yield capacity, Sy,and the ultimate capacity, Su, as shown in figureD-2.

b. Damping assumption. Another assumption re-quired for estimating damage is the amount ofdamping during the response of the building.Damping is assumed to be a constant up to theyield capacity. Above yield, the damping increasesbecause of energy absorption and dissipation frominelastic response. The damping values used in therapid analysis were given in table D-2. Further-more, damping is assumed to vary linearly be-tween the yield and ultimate capacities of thebuilding.

c Damage estimating procedure. The procedurefor estimating damage is based on the reconcilia-tion of the site demands, Sy and S, and thespectral acceleration capacities of the building, S yand S. nThe procedure is illustrated graphicallyin figure D-2. The spectral acceleration capacitiesof the building are denoted by the open circles atthe natural periods shown. The corresponding sitedemands are denoted by the black dots. Theintersection of the two lines defined by the twosets of points determines the estimated damage of60 percent. This procedure is essentially the sameas the capacity spectrum method of the SDG thatis described in paragraph 4-2d of this manual.

d. Modification to damage estimation procedure.After performing the rapid seismic analysis on afairly large number of steel buildings and woodenbuildings, comparisons of the RSAP damage esti-mates with damage observed in major earthquakesfor buildings of similar construction indicated thatthe estimated damage were much higher than theobserved. More realistic damage estimates wereobtained by applying a reduction factor Ru to theultimate site demands for steel, wooden, and rein-forced concrete and reinforced masonry buildingswith better-than-average reinforcement detailing.

(1) The reduction factor Ru is used to accountfor energy absorption and dissipation from inelas-tic seismic response of the building during actualearthquakes not accounted for by the lengtheningof the natural periods and increase in dampingfrom the yield to the ultimate level. The followingRu values are recommended:

(a) Steel Buildings: Ru = 5.0.(b) Wooden Buildings: R = 5.0 for those

buildings with a large number of interior parti-tions. For wooden warehouses and large-spanwooden structures, Ru = 1.5.

(c) Reinforced Concrete and Masonry Build-ings: Ru = 1.5 for those buildings with better-than-average detailing than required by code dur-ing their design. Otherwise, Ru = 1.0.

(2) An illustration of the effect of Ru on theestimated damage is shown in figure D-2. WithRu of 5.0, the estimated damage is reduced from60 percent to 34.4 percent.

D-5

0%

S

aWi

Ii

60U'i

Idl

9-

z

n

'I

IA

'.3

EnA1

w

1.0

0 05S 1.0 1.5 2.0

Period. (sec.)

Figure D-2. Graphical ilustration of damage estimation

( K,

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap. 13, Soc B

e. Combined building damage estimate. For eachbuilding, damage is computed for the transverseand longitudinal directions. To determine the com-bined damage for the building, it is assumed thatone-third of the building depends on the lateral-force resisting system in each principal directionand one-third depends on both directions. That is,if a lateral-force resisting element required toprovide seismic resistance in both directions isdamaged by earthquake ground shaking in onedirection, it is also damaged in the other direction.Combined damage for the building is obtained bytaking two-thirds of the damage in the morecritical direction and adding one-third of the dam-age in the other direction. For instance, if thedamages are 60 percent and 30 percent in thetransverse and longitudinal directions, the com-bined damage is 50 percent. (Note, this is essen-tially the same as paragraph 4-2d(5) of thismanual.)

f Computer aided procedure for damage esti-mates. When computing damage estimates formany buildings and/or at many different groundacceleration levels, the computation is best doneby a computer program. NCEL has developedcomputer program CEL 9 to do the calculations.The site identification, maximum site ground ac-celeration, digitized site response spectra, buildingidentification, damping values, natural periods,and spectral acceleration capacities at the yieldand ultimate levels for the transverse and longitu-dinal directions, and the replacement cost areinput into the computer. The program computesthe estimates damage and cost for the building atthe maximum site ground acceleration. The dam-age cost is obtained by multiplying the estimatedpercent damage by the replacement cost. In addi-tion, the program computes damage estimates formaximum ground accelerations between 0.05 and0.50g at 0.05g increments. A sample output fromthe program for a steel building is given in tableD-4.

g. In general, the successful application of therapid seismic analysis procedure demands experi-ence in seismic design and construction and goodengineering judgment.

D-7. Selection of buildings for detailedanalysisBased on the results from the rapid analysis, thefollowing guidelines are used in selecting build-ings for detail analysis:

a. Buildings with greater than or equal to 60percent combined damage under the maximumsite ground acceleration would definitely requiredetail analysis.

b. Buildings with greater than 30 percent com-bined damage may warrant detail analysis.

c. Buildings with relatively poor structural con-nections may require detail analysis, even if thecombined damage is less than 30 percent.

d. Essential buildings and other structures thatare required to remain functional during and aftera major earthquake are analyzed in detail as fornew buildings according to the criteria given inNAVFAC P-355.1 (e.g., SDG). Variance from thecriteria is allowed only with the consent of theapproving authority.

D-8. Visual survey of lifeline utilitiesIf an activity is to remain functional before andafter an earthquake, the lifeline utility systemsand the mechanical and electrical equipment mustalso remain functional. As a part of the rapidseismic analysis, a cursory survey is made of thelifeline utility system to determine its adequacy.The lifeline utility system at an activity includes:

* Energy* Water* Sewer* Communication* Transportationa. Network of utility elements. The effects from

the failure of an utility element of the lifelineutility system is different than the failure of abuilding in an activity with many buildings. Thefailure of a building generally has little or noeffect on the surrounding buildings, except in caseof fire. By contrast, the utility elements are part ofa network. The failure of one element can have animmediate effect on the function of the wholenetwork. A discussion of lifeline utility problemsin past earthquakes and solutions is given inNCEL TM No. 51-83-07.

b. Administrative measures. The following ad-ministrative measures are recommended to mini-mize effects from earthquake damage to lifelineutilities on the mission of an activity:

(1) Analyze and strengthen inadequate struc-tures.

(2) Provide adequate seismic bracing and/oranchorage to utility equipment and storage facil-ities (see chapters 3 and 10 of the BDM andchapter 6 of the SDG for examples).

(3) Provides standby emergency power, water,materials, storage facilities, and alternative utilityroutes to insure rapid restoration capacity.

(4) Develop disaster recovery strategies.(5) Coordinate emergency planning with other

military activities.

D-7

aI

Table D-4. Sample output of damage elimae for a steel building from computer program CEL 9

oAhA46 SIIMATES F VIOUS LV(LS OF ATOHQUAKE

DAMAG CS IIN*IC FOR VARIOUS UILO1WS Al SY LONG GZ8CH

RLDG 32 MACtIlE OOL AND ELCCISO SHOP

SUILDING POOPERIIIS AND OAMAGE EStIIAIt FO a NOMI4L ACCCLCIIAWIn Of

PCIOD DAMPING S& sin SA nITECAPACIVY DCMAND

a

ISICI LCO 'GaINANESVSE DImlCtIOiI

WIVLD LELUL1141 LWCL

LONGIIUDI4AL DIRECTION

WIELD LVfELULTIMAl LCL

2*603.b60

*.05 .130 *.it1*-10 0110 0002

-0

Z"00co

0

0

z

~In

va

n

0

0

('Ato

I40

5.006

0 .1201 .240

0- 05 0150 0.1200.10 0.ltO 0.05) S .000

BUILOING ACPLACEMENt COSI * 11210000

ESTIMAIEO TOFAL ODAKIC 10 BUILDING 64.1 PCECN

ESTIMAIED COST Of DAMAGE $ 1038012.

DAMAjE CSIINAItS FOR VARIOUS LLS OF NAXINU 6ROUN4 ACCCLCNAIINOS

tRANSVERS OIRCTION LONGIIUDINAL DECTION

SPECIRALMAX RND CCLP YIELD

C C

*.3q0.19eels*.e50.t0.150.200.250.300.35'9.*00.'S

0*50

G.0950.1260.1690.6030.06GD9101.1I35

.. 169e.20)2 31

*1.2100.3 3O*J38

ACCtLUL Io

0 *0010.-t2o.000.0010.0010*0410.0020*0020.0020.00)0.0630 .003

DAMAGEPC NI

0.00.01 9.6

0.00.00.03.2

1,.031.5*0.361.152.151.0

SPECTRALVICLO

C

0e3520.6 It0.4210.1210.2SI0. 3110.5020.1200.1560.*191.00s1.1301251

ACCELULt.

6

0.0300*0600.05)0.0110.0210.0320*0420.053016 0.07* .0*S

0.09S0.101

OAMAGE COPOINED DAMAGEPCNt PCkI

59.0 39.)11. 61.1

l0.3 0.10.0 G.e

60.S 21.012.1 *1*13.6 S0$o0.3 10.14S.O 6*2o06. 12.690.9 1.192.9 19.96.5 c2.

DAMAGE Eg11000 S

1165*240

103800

61511149630

lo3Sb3159112490931151371116151

(


D-9. Examples of the RSAP the damage estimates for the teel building andThe RSAP is illustrated by means of two exam- table D-7 gives the estimates for the concreteples. One is a steel building and the other is a building. Figures D-3 and D-4 give the buildingconcrete building. Table D-5 gives the response descriptions and the RSAP calculations for thespectra data for both examples. Table D-6 gives steel and concrete buildings, respectively.

Table )-S. Response spectra for steel building, example 1.

2.fAQmL ET1JMAUES FOR VARIOUS LEVELS OF EARTrNUAKE

0-AMAGE £iTIM.AE.QA VARIOUS S3UILDINGS AT NSY LvC, 8C-

fTGILIZE2 SLT E0P0NSE SPECTRA F )R

PE510Q JP.ESCE.N O.f CRITICAL DAMPING

. PCNT 2 PCNT S PCNr 1G PCNT 20 PCNT

LA Q_ ._JL a2.5. - 25 0.25 0.25 0.25J L..2....... ..........25 ..2S. 0.25 0.25 0.25, 305_33 0.25 '3.5

.0.10 1.15_ . .64 043 0.SA 0.320.65 Oa4 q 0.39

Q ..9 * .6;__ Q.5 0.75 0.'S 0.42I. 3?6 A) 0.79 0.63 a.46

A.30 1.03 0.32 0.63 0.4a._3C_ _ LA._. -1.10 0.13 a.63 0.49

0.%4 0 t7 _J P -A 01.1 0.62 .0.47Qd.9 1.iS __1.;15 0.77 0.'S 0a44kc5 L Q .Lb f __. 0 0 a...... a 74. . 0 5 4 0 a4 2r,;-I 5 S _,9SLQ 0. 0.49 0.51 0439,2,,a 1 .5 L __). . D 06 # ' 4^ 8 .371 ~ ~ ~ ~ 0.10.'aJq 740 C 1 ri -7.-2 O.51 0.45 0.'4

0.7n 3 __ .72JI 0 C..54 0.41 0.305ltAmQ I s12_ I. .6q 40..51 0.3i 0.29QAL.. Plj.Ol 0 .L.....a.S3. q.48 3 St 0.26rQs 29 0093 ~ C..sX 0*44 0 .. O.OS

.1-tC 0.S__ NQtLS 9, _3 jL5 4. a -041 co531 i.24.1.2 0-a 7 9 . .0 .0 .39 0.29 0.231.20 DsJ.'._- A~e.M70.36 0.27 0.221 t28 _ ?J8 3:!*** 0.34 . fl2i 0.21IL ._PLt_ . 0 .2 '3*32 0 .25 0.20

-44 0.l Q 40 0.30 0.23 0.191 .52 0 * ; 3 7 02A 0 . 22 0 .1 d1.60 0.3i5 2 .12*7 0.21 0.17

0 . 26 0.20 0.17I .76 0.51 D.2 I4 .1Q 0.161.84 0G48 0 q 31 0.23 0.1 0.151.97 2.s 0.3AO.0 .2 P.1t 0.14.00 0a44 0.2l, 3.21 0.17 0.13

a

0Table D-6. Output for steel building, example 1.

DAMAGC CSTIMATC FOR VAaIOUS LVLS Of cARtIGUANC

DAMAEc fs1tstAf Fr0 VARIOUS BUILOIGS Al SV LONG BEACH

SLOG 1 PIPE 40 COPPER S P

BUILDING PROPP0tILS AND SAIAGE SIIM4IC O A NORINAL ACCtLERII1ON

PEzoOD GAPPING S St

-4

I

0%0

Ia0

z

-n

a n-U

LI(a

-i-

I .000~~~~~~~~~~~~~P

JF

S SItEDE NANO

la$

CADACIII

LOSSMANSVEPSC GIRECIIO11

WI!LD LEVELULIIWAtE LEVEL

4SC I

* .100.150

G.e; o.0%3 s.ooze.10 0.^10 0.062

LONG0ITUDINAL IAECIIO

WIELD L"'LULVtAIE LEW.

0 .6e01.630

0.0s 0.130 Sovo.ae e.:le *oto4 5 .eee

*UILDIG RPLACEEE1 COSI * 542d000.

:

IM

a

-a

Sb

0

ESIINAICO tOtAL AMAGE 10 UILDING

[SII'AICD COSt OF GARACt S

&S.l PERCEUI

2233105.

GARAGE EStIMAtES FOR VARIOUS LEVELS OF AXIMUM 6ROU9O ACCELERATIONS

tIANSVERSC OlRfCbON LONGItUDINAL DIRCCIION

iPECIRAL ACCELMAN SAND ACCLo fIELO UL

S C C

0.160-1VI.20.050.a00.5S0.200.250.0*s 3s0.600.450.50

I 6.4e s.'t

.e622306

*321I3.*46

.6*2).R02.*2

1.612I 203I .666I .406

0.06*0.e020.020.o3*.o033

0.0690.04*0.0 20.000.l110.*13s.l3o9.161

OARAGE

0.015.6

s.e0.0s.o

1".535.*

55.31.0

664 e

SP;CIRAL CCEL'ICLD UL..

C CoANAEc CORSINCO OAM46'PCNI VC49

0.5930 *4 15oelsslcos IGOIS&

1 .6220.31legal

I1.265I *eea .00aa .5"

0.002*0.035%8.6*0.0090.0 190.0200.031a006Sol$&0.0*1a00160.0A60.0093

*2a612.514. I I .366.44.I1*.019.9a0.904.409. 2la.092.6

1*.*513*5.1

P532.661.3

5.6*Is.tieS14*00.*02. &S.3

DARASE S1

1013

2231250

list16611914223126532*1121432062.2923

(

Table D-7. Output for concrete building, example 2.

V144C t SAttICS 014 VttOUS LEtrLS pfJ1ft59H UKE

(

"SMACt ttMAtE F2 9alQlu1 BUILOIGSSAI I LONG tAKC"

"t0o 12" 14 41mt q.*Ct9tgI

1u1l10 PRSOERIICS A90 oMcA IstaaIMr roi i kOSitAt CC'TCRAIIOI

PtPIO GANPIhO SA SIRCAPACIlT

Isico tootASIWVERSt OIE1C1I419

WIlLS ttt 6.60 G.s 6.320UTIR1E ILVEL. 1.156 .10 .**ê

LCWSIIUOI"BL OttEC194

ICLO LVIL S.li 6.65 0.030ULTM*5 LEVEL. 901.6 .es O..Sa

O 1M5 SO ltt

CiMAWO

too

0.04L.62 I eae

I .eoe.3120.*65

6UILDIM& REPLACIEEI COSt 66 **566.

CSIIRICO 1011. OlMqOOC to Sultolng flat.PECrtIT

CStIIISO COSt Of 0A19e0 a 3512153.

OA`1GCt S1IN*1CS FOR WrVfllUS LCLS Of "I"PUN OUtO CCCLCfR*1O3N

19R*SwtCSE OtRECItaW

194*116 qO CCt.

C.l6

6l.23

3.25a.30

o.oo

6.66

qf60605Getsfe S

SPM INL CCIL*IfLU S r,

r, 4

I .229lost&o

1.316.0121.062) .2*5

. a.

.31t

3 ,413

0.261a * 3610.562

6.2016.361

*6.502e*set.tt.o ao

*s936I,.,,

O40AGEPCNI

6.0

e.e6.o6.60.61.5

16.Mese of.Mae,ile,

LONGIIUOIRAL OIRECIION

SPECtRAL CCL1IttO tI. DAMAGE

a C PCMt

0.26 6.252 .e6.263 0.355 *.6.312 6.066 63.26.010 06.0 6.66.169 Gets? 6.60.223 0.261 G.60.299 6.316 6.00.312 6.*66 63.2*seed, 98s6a aoode*56 *.eos ..6l3I5 6.*16 It.6.6,95 6*1 106.6.0.s10 O."t2 100es

COmSIW!0 04M46£PC"t

6.S60e~e

o.0.o

Ss.,

goodee.o0Is6.6l66.6

D*N*SC Est1660

.63512

...

224351206164

6636.:16616.

I

TM 5-809-102/NAVFAC P-355.2AFM 88-3, Chap. 13, Sec B

BulJsiI 131 - Pe anJ CoIipa Shop

Bv fJ In: ta a

On c-s'to y sce (ra me 6u 1D ros; is 19401 22 t X 402 t p flon X 3.5 (f A;,ph

Conqtruct4on

L ar 4(Iy racec cl eI clravm csQv_,0=, brasl> >¢S etafto,a"W ~ ~ ~ ~~~~6 mIAr.vc.asg .

R Ru CT Co n n .ca-

Founoteen conm~s Ts oC { nc et. sI~a S upp- t.ad oa CO ic'e'C Or Fd,5

L areral 4C c rssZtrn sysTecm

Sreal le-eti Cs wh -oc trca l,, tAc lonetuJmn-l Jrectan

Beam- eraer

27 W24 74

ZO - o30X 116

Co fu nnns

ZZ- W o x 33

ZZ- W I0X 45

Sheet 1 of 7

igure D-3. Eample of steel building. (Sheet I of )

D-12

TM 5-809-10-2/NAVFAC P-3S5.2/AFM 88-3, Chap. 13, Sec B

CROSS - fSECTION

%, .le .V Z S 9J;hXsh Al44A< - X

4Cr*AC Way

402

N#4

I.

PLAN

Sheet 2 of 7

Figure D-3. ExamPle of tel building. (Sheet 2 of 7)

TM 5-809-102/NAVFAC P-355.2AFM 88-3, Chap. 13, Sec B

RPOOC . (rams"O :wl 5 1Mosc

Spec.-tral A .c lermcztto"

25 f

I o5

4.0 f zA re

x (I 2 ZX 4 OZ) 1961 8

CQ C. c t cs F 36. 1sg

COlurn-Is hA f = 15, '/z = 7, 5 '

W lOx33F s

- h44

84W. c: /.I. 5~)7:5' (az j')

1 §4. /coi.

-v F sz =hy ; C ~ j = 4. '38'6)

W 10x4s

r = 14. /(E) =

14. ;1e.0 t. ( 9"' ) -=3.73 2

At leId

Lzo-:. VC I= _ 262=Ot ( 3 e- eC 1. + 37 3, I. )

Tens. CI/ Yc. 2 Z I. ( 4%/o./. + 3 1. C 1.)1003,Z A.

Sheet 3 of 7

Figure D-3. Eample of steel building. (Sheet 3 of 7)

D-14

Di

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap. 13, Sac B

At I t,.oTc:

Lo *c 1. 5, V Z.G j 3.gC/C~~C~

Tra : .Z VO-IC 61.2 v is 21203,.

aWo-%aI racez . only c((ecel.ue tus sfon

Sir sTs. o 3 , J 3 Jr 6

mcci BcI& s conuircT-cJ 6eit.y o40"r

so sI/C heshej,-. 40 4

A 3.0 ;nf 5*v7Z

B ovc '

4! = t4 A) 36. Ls (,0 t)(z7z)

= 101-I

F'OJ., 7 a rIeTrs :

.S w 0'' 8 4'876t.5 = f44 'r'4z,4z)

X,; ) -S4 Z. 2 ,4 ctControl.

-5treojz -0, ic SIA Saov,4a ac :

is 6 4 .zA) -Z.

TOVh lze; ,coto tto r s

TotaI s- f

At -21Lid

Lon 1:I I

-e- t~-

2 5. 2-.. W. 0.13

Sheet 4 of 7

Figure D-3. Example of steel building. (Sheet 4 of 7)

D-1S

TM 5-809-10-VNAVFAC P-355.2/AFM 88-3, Chap. 13, Sec B

7T47$A . 4 I D i . Z .- -c 19r 1 a k - o St

A4t u r, Tzr

S~MIj'Z53.Z + Z.

1961.8

Tsa.: S. = 203 . _I ac1 I4

0.61

NcLtura I PcrioJs

7-Y I Z (z~rIF-

m" , WI3Z.2

= 094 Sc

Co.nn st;Um -roinc s c I = 12EI

c0 ;S ~L 3

Lo on. k = zzC-0

Ti?,3 53 +3v.7

= /,IC I - /k

Tro ns.:

I

Gt (s . (2Q , /44)y J . 70 )

= IAX, Z8 9./#.

sJ ff-eoss W

Ae(. B_ . ea X to <o, Z2.7z J 42. 7Z 4 2. 72)

Sheet 5 of 7

k I


D-16

TM 5-809-10-2NAVFAC P-355.2AFM 88-3, Chap. 13, Sc B

k - 6 (1847.0 k/;t-)

L .-, P

J -1O8z't

-- I- Io 1Os. ^/f+ ,161. M~A kod- A I 2

,LI za 4 Iter

-r ye-Z V5rt6 0.9 - s C r = a.44 Cc

Ty . Tr 0 -<°' e i *'i - 0.41 sC,

At cIttor" e

Lo vi. . 00dy ticc/ yeC

colewo/nvv e e a 'e

T77d

I 0.442z Z4 S.

/ 43 sec.

7ale

0.41 S94: = 0.41 4/.Z

= 0.75 Sec

Sheet 6 of 7

Figure DI-. Exampl of steel building. (Sheet 6 of 7)

D-1 7

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap. 13, See B

S u rnm ry

. _ _ _ _ _ _ _ _ _ __T __sc S) s ' )

At Y,,c ULo-n ). 0.44 0.13Treais. 0.4 1 0.51

At UltimoteLo . 1 .43 0.21ro-.0"19 0.75 0.61

-Ae rro" w npct-a*s g I i di 7vIAI ac D-S.

usa t Ioogl -h. Lu/dJb.

Co.putcr oUtput or ic btelJ :a CS ocu.'M.bl 0O6 .c co anaJ da4, 4or tkcbuIIJ;vi at .Z6 s 6!.1- U.cnce ,M buil-daa 5 rej' wttse A7an".4iA .1. 1 htsv cn 14n c-

e-*+s~~~~~~~. p/tsxtc] A dcicM" yo x~ws 9nc2br^J COnnectiws anJ/o lv 1i g s%.a-#on o n

nc~u dIegO~nosr~fces,

Sheet 7 of ?


D-1 8


BuejlJpng 129 E- Marine MachSnc Shep

Bua1clen Dotex

One- tor rinorcc-ed concrc-t 1Aldancj w 9 lHs uomc Zma n Inc sDrcLuon rv 194417Z ict X z75 ft n plam X 34 (Ct hg

C onstruclton

Reas,"orccl concrete renacs And sca lls.~a~lf-up Li ewics over coAzrcreTe rc s cicab

Co0crere la b eChXo4.t Ofl

Lca~tesca l - orsce Oal Ct. g yslen,

S;icsOr ,ccOl C. ~ rbtcwC

Beamn,No .242424

_36Tctc I = toe

5.e (;_ )

4AX 16l4 - 2815 X ZIf X !Z

16 30 w Awcra2 c

CO/umns

-I.tl I

.,o.12lZ2412

60

S I e v .)

14 X 18i rx 1618xZ4te X30IkX24 w A cm71

Sheet 1 of 6

Figure D-4. Example of concrete building. (Sheet I of 6)

D-1 9

'TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chap. 13, Sac B

SI~eor Walls

E Nr C:oy-

I&4teror

oten 8,7,5

6 ;. othi fIannoy ,(o

W et7 Ab o t s1

";ith Ac: 2111 kof w 4 1 r ,"9 s ,

tN

JI I 0*taI I

~~~~~~~~~~~~%, * 1I I u

L- 275' -

PLAN

0I ©9 0

CROSS - SECTIOW

Sheet 2 of 6

Figure D-4. Example of concrete building. (Sheet 2 of 6)

D-20

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop. 13, Sec B

We l&t1-.

Poet

Bca mr.is I~ ~~~ G 60 { 00 1bl/"

50._1 = zo /f2 5 o t f

6 50Pcr) = 76 ,5

Osc 100 fwf&9

UL ls1050 lfnel r ; 0otD ;. -MIc-t "JcO//.

of TvMbu1ory I5X4,,

5' ( ) o Pci) (to 694 =J /6 8 6f501r

_156.as0 It. (1I 72' ) Z 75 ')

Seacnic. L4Jea7 1t

Ra:o e jrom.cnLRL, I/s&ves c-.

33. s pwo

USC 3 Fps

100 95

J50 Pst

Wefciht a 0.15 0psr C17Z'XZ75')= 70 96.

Sheet 3 of 6


D-21


s petra I Acc c le a toui Co gv *1izes

1. vir5. 4 'ra~i lhcowr gtcth' 77 or cencdP7columns cnJ ahEvr w/s = IOG~i~t

2, Owaly onc-7AtirJ ofc fwn C.OUs-jSccttonog~ I oC 5 zfcltis in res.?-

t'e9sctsc sh-f orrx.

C Ci - 16. n.

Vcv -23,6-4no. 4k/ew)3lw

V= 1. *18 .=

Shear Wall-

L o"7.(55 it) (:z2./fP)(a .,.) (0.)4 (.51r) (,a"/t)(6 *;")(J 0)

, . kdZ~za zoo;..'

V 04ZO.vWD~

TnM s. .+ (040)(a2 ;#)(IJ) , 2) a)

= Z'6,5 29102%

S W t Z 9.*

Sheet 4 of 6


D-22


Totl I C .cef1i-

At ItUllatc

Loengi, a =I c _ ZBOk 47ss 15.0 -Iw 70 k

= 0.51

TVa ns. 5> LJe, ~ C}= 2669 + 7 de

-= 048

At YIJ

L orT.I

S Ia ye

C

S9a~,

0.5I-. 5 0..34

Tra n s. 0.48- 8

Naturo I Prcs Jc

At Yic J

Lo,. : Tr -. 0.5 h, Tr c °' n=xS FI

0.05 Czz)t) 2=7 7

- 0 07 s c.

&r' .5 -r qm 0.05(TC22O._______ )_ _ o , __ ¢c

LY 17Z ~ Im=

At OIrt.latc

Tran s. :

TS. A Z Tr w 2(0.07r0-.14,ScC

27r, Z(O.oS8) 0.16 sec

Sheet 5 of 6


D-23

TM 5-809-102/NAVFAC P-355.2/AFM 88-3, Chap. 13, Sec B

-6tCc) S; Cg)

At YIJLoni. 0.07 0.34Tenc. 0.08 0.32

At 01t? eatLoncj. 0.14 a5

Tme S. 0. C 0.4

7hc rcs pewss 4& T'=rr uscJ ti oaIl h bac bJue,"was g *sen C P D-S

7c co wPu"TorAn Table D-17.

4 wnaxamL'mOoo 20 s 0Th=

oulp! l CoWO 'hc bIJn as shosuT7Na JcO obt10.er' 11 'cshOIJ #5 at

0j -'O u s CwLc<rteraCrfo at;, ° OVcst~no~cJcow"468n 6C J"daL

t o.25g a$Sc21to 5 61.1%. hus, AiebuI lJ e' Is jild4 J.geo.Tc nd rcu'rez *tlnfcg~ yartuc & a is-i 7ttc 7 'w' n L' rs e Sitr a'o o n .

7rhws Csi he acconpa shi d by SKck wnng 1Yic

Ij 5 tn, s wall, wulA .Iiotnctc ranV/or1/a c, o 0 of d'uJ i e rntIo r r aas .Unde,'sraflJe~bt load putmuc t ASc rvnoc;deto le' onew skar wal'ls to 7nansecr scasneac

U-r'C t'o thn , htoa th r- t O'IhJ bn l t h.oU V14 oV I O tn s 7I.

Sheet 6 of 6


D-24

TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chap 13, Sec B

APPENDIX E

GUIDELINES FOR THE EVALUATION OF EXISTING MATERIALS

E-1. IntroductionMany existing buildings may have less strength inmembers and connections than they would have ifthey were constructed more recently. This is dueto: poor quality control and detailing practicesspecified at the date of construction; damage ordeterioration of structural materials with age oruse; and uncertainties in the estimation of thematerial and section properties. This differencemay be taken into account by assigning capacityreduction factors to members in buildings. Thesefactors should be determined in accordance withthe engineers' assessment of the existing condi-tions of the building under consideration, theconfidence level of the estimating material proper-ties, and the workmanship. Physical properties ofexisting materials are usually available in theoriginal design drawings and construction docu-ments. In the absence of existing data, field inves-tigation and tests of sample members may berequired as described in this appendix. The bend-ing moment, shear, and axial load capacities ofcritical members in existing buildings will bedetermined assuming that they have the sameyield strength as the new materials. Rehabilita-tion of some existing structural materials to re-main in an upgraded building may be required inaddition to the modification or strengthening ofother materials. Where rehabilitation of damagedor deteriorated structural material is not feasibleor ost effective, capacity reduction factors, asdescribed above, may be assigned to the existingmembers if the member is capable of resistingloads, but at reduced capacity (e.g., a steel beamthat has suffereed a measurable loss of section dueto corrosion).

E-2. Ph ial properties of existingbuilding materials

a. Structural steel. Physical properties of steelmembers and connections can be determined withreasonable confidence from the review of existingdata and/or field inspection. If the age of thebuilding is known, the physical properties of thesteel members may be inferred by reference tomanuals or specifications of that time period.

b. Concrete.(1) Reinforced concrete. With reinforced con-

crete elements, it is essential to estimate thecompressive stress (fe) of concrete and the mini-mum yield stress (fY) of reinforcing steel. In addi-

tion, the amount of reinforcement and connectiondetails are important factors in evaluating thecapacity of reinforced concrete members. Fieldtests described in paragraph E-3 may be requiredto verify the existing data available from theas-built drawings and construction documents.

(2) Unreinforced concrete. Although unrein-forced concrete construction is permitted only inthe design of pedestal or footing not on piles, inaccordance with recent building codes, most un-reinforced concrete components used as structuralor nonstructural elements in older buildings havesome structural capacity that should be consideredin the capacity evaluation. The capacity criteria ofunreinforced concrete elements in existing build-ings may be determined considering 5vF for flex-ural tension and 21f for shear. Capacity reductionfactors should be assigned to account for uncer-tainties in material evaluation and workmanshipof the construction.

c. Masonry.(1) Reinforced masonry. The capacity evalua-

tion of reinforced and unreinforced masonry ele-ments in existing buildings is rather difficult.Because age and deterioration may affect thecapacity of existing masonry elements; the type ofmasonry and the quality of mortar are generallyunknown; construction details may be greatly dif-ferent from current practices; testing is expensive;and interpretation of the test results may bedifficult. Despite the above deficiencies, field andlaboratory tests of sample members prescribed inparagraph E-3 are advisable. However, in somecases, it may be less expensive to assume aminimum compressive strength (f m) consistentwith the codes and construction practices at thedate of construction rather than to perform exten-sive field and/or load tests.

(2) Unreinforced masonry. Unreinforced ma-sonry construction is generally not permitted indesign to resist seismic forces, in accordance withcurrent building codes. However, most unrein-forced masonry elements used either as nonstruc-tural partitions or structural elements in existingbuildings have some structural capacity andshould be considered in the capacity evaluation ofexisting buildings. The yield strength criteria ofexisting unreinforced elements may be assumed1.7 times working stresses specified in agencymanuals for ordinary or nonseismic construction.Capacity reduction factors may be assigned to takeinto account uncertainties in material evaluation

E-1

TM 5-809-10-2NAVFAC P-355.2IAFM 88-3, Chop 13, Sec B

and workmanship of the construction.d. Timber. The physical properties of wood

members and connections may be determined fromfield inspection and existing data shown in theoriginal design and construction documents. Whengrade marks are available, appropriate physicalproperties may be determined by referring torecommended design values by the National De-sign Specification for Wood Construction or otherrelevant documents. Conversely, when* grademarks are not available but such information isessential, field inspection and/or tests should beperformed to evaluate the quality of the materialsand their strength properties. However, in somecases, finishes or members must be removed forthe field inspection. The decision to undertakeextensive explorations involving the removal offinishes should be made by weighing the benefitsgained against the costs of such exploration.

e. Foundations. Evaluation of the capacity ofexisting foundations requires the evaluation of thestructural materials (i.e., concrete, piles, drilledpiers, etc.) as well as the soil properties. Consulta-tion by a qualified soils engineer and field investi-gations, including borings and soil tests, may berequired to establish appropriate soil properties forthe structural performance levels prescribed inthis manual.

E-3. Testing criteria for existing mate-rials

Determination of the physical properties of mate-rial may be made by in-place, nondestructivetesting (NDT), removal of samples for destructivetesting, or a combination of both. These two testprocedures are described in this paragraph.

a. Nondestructive tests (NDI). The NDT ap-proach has been used for many years for metallicand homogeneous materials. Because the directdetermination of strength implies that a sampleelement must be loaded to failure, it becomes clearthat the NDT methods cannot be expected to yieldabsolute values of strength and are limited inaccuracy. The NDT methods for nonmetallic con-struction materials usually attempt to measuresome other property of the material from which anestimate of its strength, its durability, and itselastic parameters are obtained. Some of the NDTmethods described below are not truly "nonde-structive." They are considered to be relativelynondestructive, in that they generally leave onlyminor surface damages that can be repaired. Onthe other hand, coring or cutting is usually consid-ered to be a destructive test.

(1) Surface hardness tests.(a) These tests are an indentation type and

consist essentially of impacting the surface of

concrete in a standard manner, using a given massactivated by a given energy level, and measuringthe size of indentation. The three known methodsemploying the indentation principle are: Williamstesting pistol, Frank spring hammer, and Einbeckpendulum hammer. The test methods are usedonly for estimating concrete strength.

(b) In-place Brinnel and Rockwell hardnesstesters are commonly used in the field to estimatethe tensile strength and to establish the grade ofstructural steel or reinforcing steel. These two testmethods are standardized in ASTM E 10 andASTM E 18, respectively.

(2) Rebound tests. The Schmidt rebound ham-mer measures the elastic rebound of concrete andis primarily used for estimation of concretestrength and comparative investigation. Themethod provides an inexpensive, simple, and quickmethod for nondestructive testing of concrete, buthas serious limitations. It should not be regardedas a substitute for standard compression tests, ,butas a method for determining the uniformity ofconcrete in structure and comparing one concreteagainst another. The Schmidt rebound hammertests are standardized in ASTM C 805.

(3) Pentration techniques. These techniques in-clude the use of the Simbi hammer, Spit pins, andthe Windsor probe. They measure the penetrationof concrete and are used for strength estimationsand for determining the relative strength of con-crete in the same structure. Like other hardnesstesters, these methods should not be expected toyield absolute values of strength of concrete in astructure. The Windsor probe system is standard-ized in ASTM C 803.

(4) Ultrasonic pulse velocity method. Thismethod is used to evaluate uniformity of metallicor nonmetallic material and to estimate itsstrength and elastic properties. This method in-volves measurement of time of travel of electroni-cally generated mechanical pulses through a medium, the time interval being measured by adigital meter and/or a cathode-ray oscilloscope.This method has gained considerable acceptance inquality contol operations. It has become a commonmethod on construction sites when structural steelwelding is involved. The tests can be carried outon both laboratory-sized test speciments and com-plete structures. The pulse velocity method isstandardized in ASTM C 597.

(5) Radioactive methods. These methods in-clude the X-ray and gamma ray penetration testsfor the determination of rebar and strand locationand size, voids in concrete and masonry walls,location of anchors in stone masonry, as well asthe detection of weld flaws. The principle of thesemethods is to place the radiation source on one

E-2


side of the member to be inspected and the film onthe other. The X-rays or gamma rays penetratethe member, but undergo attenuation in the pro-cess. The degree of attenuation depends on thekind of matter traversed, its thickness, and thewavelength (or energy) of the radiation. The maxi-mum member thickness is limited to about twofeet. The high initial cost and the immobility oftesting equipment in the field, in the case ofX-rays, have been the main limitations of thesemethods. The use of gamma rays has been moreacceptable in construction testing because sourcessuch as cobalt and iridium are more portable thanX-ray equipment and are easier to use on in situmaterials. Tu utilize these methods, both sides of amember must be accessible and very strict safetymeasures must be taken, as the radiation can belethal.

(6) Magnetic methods.(a) The Pachometer and cover meters are

magnetic devices that can measure the depth ofreinforcement cover in concrete and detect theposition of reinforcement bars. The methods arebased on the principle that the presence of steelaffects the field of an electromagnet. The devicesgive satisfactory results if structural members arelightly reinforced. In heavily reinforced sections,the effect of secondary reinforcement may influ-ence the dial reading, and the satisfactory determi-nation of the cover to steel is practically impossi-ble.

(b) The magnetic particle method is usedprimarily to locate surface cracks and to detectdiscontinuities of weld joints on or close to metalsurfaces. In this method, an intense magnetic fieldis set up and magnetic particles are applied to thesurface of a section under consideration. Particleswill collect at lines of defects. Various colors ofmagnetic particles are available and can be se-lected on the basis of contrast with the materialsurface.

(7) Nuclear methods. The techniques includethe neutron-scattering method for moisture-contentdetermination and the neutron-activation methodfor cement-content determination. These methodsare not suitable for determining the strengthproperties of concrete. The application of nuclearmethods is still in the experimental stage. Theequipment required is relatively sophisticated andexpensive.

(8) Electrical methods. The application of elec-trical methods has been along the lines of: deter-mination of moisture content of concrete by dielec-tric measurements, tracing of moisture permeationthrough concrete by electrical resistivity probes,and determination of thickness of concrete pay-ments by electrical resistivity measurements. Be-

cause the development of electrical methods forconcrete is limited to specialized applications only,these methods have received very limited accep-tance by the concrete industry.

(9) Microwave absorption techniques. Thesetechniques have been used to estimate the mois-ture content and thickness of concrete. Because ofthe electromagnetic nature of the microwaves,they can be reflected, diffracted, and absorbed. Theabsorption of these waves by water has led to thedevelopment of a method of determining the mois-ture content of concrete and brick. These tech-niques are still in the development stage and arenot ready for much practical application.

(10) Acoustic emission techniques. These tech-niques have been used to study the initiation andgrowth of cracks in metals and concrete, but theyare still in their infancy.

(11) Load tests. The gravity load testing of astructure or a segment is used to establish thefactor of safety with respect to the simulated deadand live loads. Floor or roof flexural members arethe most frequently tested. However, vertical ele-ments can also be tested with similar techniques.American Concrete Institute Building Code Re-quirements (ACI 318-83), Chapter 20, and the.Uniform Building Code (UBC), Section 2620, pre-scribe criteria for the acceptance of a test compo-nent. The applied load is specified as 85 percent ofthe sum of 1.4 times the dead load plus 1.7 timesthe live load. If the maximum deflection of abeam, floor, or roof exceeds the square of the spandivided by the product of the member thicknessand 20,000, the deflection recovery within 24hours after the removal of the test load must be atleast 75 percent of the maximum deflection. If themeasured maximum deflection is less than thisvalue, no deflection recovery requirements areimposed. The load tests are considered to be themost expedient method of establishing the safetyof a structure with respect to gravity loading.With the exception of individual frames, it isgenerally not practical to load test for lateralforces.

(12) Dynamic response testing. The techniqueof artificially exciting a structure to determine itsdynamic response characteristics is occasionallyperformed. The test results are useful to verify theadequacy and reliability of structural models de-veloped during the analytical phase of buildingrehabilitation. Measurements of accelerations, dis-placements, and strains are often required. Thestructure can be excited by vibration generators ora low-amplitude pull-and-release technique.

(13) Strain measurements. Load, strain, anddisplacement measurements are commonly used inconnection with static and dynamic load tests to

E-3

-- -

TM 5-809-10-2INAVFAC P-355.2IAFM 88-3, Chop 13, Sac B

monitor the response of a structure. Electricalresistance strain gauges bonded to members atstrategic locations are used to monitor changes inelectrical resistance. Displacement and force mea-surements may be done remotely by electronicdevices or by direct measurements such as dyna-mometers, potentiometers, or others.

b. Testing criteria of sample materials. Visualfield inspection is probably the most importantand least expensive method of quality assurance,but it is limited to surface evaluation. Othermethods of nondestructive and destructive testingmust be supplemented with visual inspection forfull quality assurance. Sample materials should beselected objectively, so that sample elements arenot weighted to be nonrepresentative. Further-more, sample locations should be spread randomlyor systematically over the structure in question.This paragraph prescribes the criteria for destruc-tive testing of sample materials and summarizessome of the nondestructive testing methods de-scribed above which are commonly employed infield and laboratory tests for certain constructionmaterials.

(1) Structural steel.(a) Destructive testing. Material used in

older buildings may no longer be in current useand, therefore, must be identified by reference toASTM designations and specifications which werein effect at the time of construction. In the absenceof existing data, the destructive testing of samplematerials cut from sections of a structure shouldbe made, along with nondestructive tests describedbelow. The laboratory testing of tensile strengthand other pertinent material properties should beperformed in accordance with ASTM A 370. Intaking sample elements, special care must betaken to not reduce the load-carrying capacity ofthe structure. When material is removed at criti-cal sections, temporary supporting may be needed.

(b) Nondestructive testing.1. Verification of dimensions. Visual mea-

surement, size, thickness, and material uniformity,including possible corrosion, can be accurately andquickly determined by the ultrasonic pulse veloc-ity method (ASTM C 597).

2. Determination of in-place tensilestrength. In-place Rockwell (ASTM E 18) andBrinnell (ASTM E 10) hardness testers can be usedto estimate the tensile strength and to establishthe grade of steel.

3. Inspection of welds. The nondestructivetesting of welds and weld-related material plays avery important part in quality assurance. In addi-tion to visually determining size and apparentquality, nondestructive methods for flaw detection,such as the ultrasonic pulse velocity method, the

radioactive method, the magnetic particle method,and the liquid penetrant method. The use ofpenetrants is especially useful in the detection oftight surface cracks which might not be detectedeasily by visual examination.

(c) Load tests and dynamic response mea-surements. Load tests may be used to establish thesafety of a structure with respect to gravity load.Dynamic response measurements may be desirablewhen doubt arises concerning the adequacy andreliability of mathematical models developed dur-ing the analytical phase of building rehabilitation.

(2) Reinforced concrete.(a) Destructive testing. Cores provide the

best qualitative method for determining compres-sive strength, unit weight of concrete, Poisson'sratio, and modulus of elasticity of existing struc-tures, which are essential for determining struc-tural capacity of existing elements. A standardsize of core is 6 in. by 12 in. (diameter by height);however, a 4-in.-diameter core may be acceptable.The ideal core will have a height-to-diameter ratioof 2.0, but not less than 1.0. In taking cores and inexposing and removing steel reinforcement, specialcare must be taken to not reduce the load-carryingcapacity of the structure. Samples should be repre-sentative, and they should be done in a way toavoid rebars. The number of cores depends on thepurpose of coring and the size of the structure. Aminimum of three cores is recommended. Thetesting criteria have been standardized in ASTM C42. The destructive core testing should be per-formed along with one or more of the nondestruc-tive tests below.

(b) Nondestructive testing.1. Uniformity of concrete. The Windsor

probe system (ASTM C 803), the Schmidt hammer(ASTM C 805), and the ultrasonic pulse velocitymethod (ASTM C 597) can be used to determinethe uniformity of field concrete.

2. Crack detection. Crack depth, size, di-rection, and propagation can usually be deter-mined with the pulse velocity equipment (ASTM C597).

3. Location and size of reinforcing bars.The Pachometer can be used to locate reinforcingsteel, size, and depth of cover.

4. Strength of reinforcing bars. The chip-ping gun can be used to expose reinforcing steel.Access will provide the opportunity to establishthe grade visually. However, an in-place RockwellASTM E 18 or Brinnell ASTM E 10 tester can beused to establish the grade of reinforcing steel if itcannot be determined visually. Alternatively, alaboratory tensile test (ASTM A 37) may be per-formed if more accurate tensile strength is desired.

(c) Load tests and dynamic response mea-

E-4

TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chop 13, Sec B

surements. Load tests prescribed in ACI 318-83,Chapter 20, and UBC, Section 2620, may be usedto determine the safety of a structure with respectto the gravity loading. Dynamic response measure-ments may be useful in the development of realis-tic analytical models for seismic safety evaluation.

(3) Masonry.(a) Destructive testing. The traditional

method of determining shear strength of mortar isto cut an 8-in. core and test the core in thelaboratory with the bed joint rotated to a position15 degrees off vertical. Disadvantages are: thecoring machine is cumbersome, water is requiredin cutting and is difficult to control, the sample isoften damaged during cutting, and the resultinghole is difficult and expensive to repair. An alter-nate method is the in-place push test developed inconjunction with Division 68-Earthquake HazardReduction in Existing Buildings for the City of LosAngeles. In this method, a brick adjacent to thetest brick is removed by drilling or sawing out themortar joint. The head joint on the opposite end isalso removed. A calibrated ram is placed in thespace left by the removed brick and a load isapplied until the test brick's bond is broken. Thistest is simple to perform and is nondestructive. Itis easy to repair and relatively inexpensive. Thistest has the advantage of retaining the actualvertical load on the test brick, a condition that isdifficult to achieve in laboratory testing. The testsare usually conducted at various heights to varythe actual dead load condition and at horizontallocations to minimize concentrations of load. Thedesirable frequency of tests is one test sample per1,500 ft2 of wall area with a minimum of two testsper wall. The following structural properties ofmasonry walls are usually of interest to theengineer in evaluating the structural capacities ofmasonry elements.

m= compressive strengthf' = shear strength under diagonal com-

pression, ASTM E 447f t = tensile strength under out-of-place flex-

ure and lateral loading, ASTM E 519G = modulus of rigidity

The ASTM tests cited above are written for field-constructed test samples rather than drilled orsawn samples; however, the same criteria can beused with a few slight modifications.

Guidelines for selection of sample specimen maybe consulted in the National Bureau of Standardsstudy for the Veterans Administration titled"Evaluation of Strength of Existing MasonryWalls."

(b) Nondestructive testing.1. Location and size of rebars. The radio-

active methods (X-ray or gamma ray) are oftenused to determine the location and direction ofrebars, depth below surface, and size of reinforce-ment when both sides of a wall are accessible. ThePachometer can also be used for the same purposewhen one or both sides are exposed.

2. Uniformity of masonry. Voids and rockpocket areas of a double-wythe brick wall with agrout or concrete infill can be detected by theultrasonic pulse velocity method.

(c) Load tests and dynamic response mea-surement. Load tests may be used to determinethe safety of-an element or a structure to resistthe gravity design loads.

E-4. Rehabilitation of existing struc-tural materials

Rehabilitation of existing damaged or deterioratedstructural materials may be a significant factor inthe seismic upgrading of some existing buildings,incidental to, or in addition to structural modifica-tions and strengthening procedures. Following arerepresentative examples of feasible rehabilitationfor various structural members:

a Structural steel Moderate accidental damage,such as bent flanges, may be repaired by flamestraightening and/or jacking or peening. Caremust be taken to shore loaded steel members priorto heating. Corroded or otherwise deterioratedremovable elements of steel framing, such asbolted bracing and fasteners, may be replaced withnew elements. Scale and other corrosion by-products shall be removed and the steel memberslightly sandblasted in preparation for a rust pre-ventative undercoat and painting. The loss ofeffective section can be evaluated after sandblast-ing and the assigned capacity reduction factor willbe re-evaluated.

b. Reinforced concrete. Prior to undertaking therehabilitation of existing concrete structures, theapparent cause of the damage must be ascertained.

(1) If cracking or other signs of distress can berelated to differential settlement due to consolida-tion of the soil under the footings, soil investiga-tions will be necessary to determine anticipatedfuture consolidation and the cost effectiveness ofrehabilitation.

(2) If the cracking is related to the shrinkageand heaving of expansive soils under the founda-tions, rehabilitation may be cost effective if supple-mentary measures are taken to restrict excessivechanges in the moisture content of the soil. Thesemeasures may include removal of foundationplanting and paving a strip to exclude moisturefrom the soil around the perimeter of the building.For buildings with exposed soil in crawl spacesunder the first floor, a moisture barrier with a

E-5


sand or concrete cover may also be required.(3) Cracks in concrete walls may also be due

to initial drying shrinkage of the concrete or totemperature expansion and contraction. Hairlinecracks are normal in concrete structures and havelittle or no detrimental effect on its strength.Evidence of rust stains at a concrete crack mayindicate that moisture is intruding and corrodingthe reinforcement. If this is not corrected, thecorrosion will progress and eventually spall theconcrete surface. When this condition exists, thecrack should be routed out to expose the reinforce-ment which should be thoroughly cleaned by wire-brushing prior to patching the crack with an epoxymortar. Although it may not be possible to preventthe cracking due to temperature expansion andcontraction, control joints are effective in limitingthe location of these cracks. Vertical control jointscan be sawed in the outside face of concrete wallsat about 8 foot centers to a depth of about V-inch.The sawed joint is then filled with an elastomericsealer to exclude water. Epoxy injection is aneffective method for sealing concrete cracks andrestoring shear strength. Epoxy injection requiresspecial equipment and procedures and is bestaccomplished by an experienced specialty contrac-tor.

(4) Spalling of concrete surfaces in cold cli-mates is usually caused by the freezing and expan-sion of water intruding into the pore spaces of theconcrete. This may be prevented by a suitableelastomeric coating to exclude the moisture.

c Masonry. The various causative factors con-tributing to the cracking of concrete walls, and themitigation of those factors, described in the preced-ing paragraph, also apply to masonry walls. Theweakest element in older masonry is usually themortar joint, particularly where significantamounts of lime was included in the mortar andsubsequently leached out by exposure to theweather. For this reason, cracks in masonry wallswill usually occur in the joints, although occasion-ally well-bonded masonry will crack through themasonry unit. Epoxy injection is the recommendedprocedure for sealing cracks and restoring shearstrength for masonry walls with cracks in thejoints or through solid masonry units. Wherecracks occur through hollow masonry units, it maybe feasible to pump mortar in the cracked units torestore shear strength prior to epoxy injection ofthe face shells. A common problem in masonrywalls is the intrusion of moisture to the inside ofthe building through the joints where the mortarhas cracked or where the drying shrinkage of themortar or the units has formed a path for moistureto penetrate the wall. This condition can be reme-

died by routing out the mortar joints in theexterior face of the wall to a depth of about½-inch and sealing the joint with an elastomericjoint sealer.

d Timber. Common problems, requiring reha-bilitation of timber structures, include termiteattack, fungus ("dry rot" or "damp rot"), andwarping, splitting or checking due to shrinkage orother causes.

(1) Insect damage. The subterraneous termitesare the most common termite variety in theUnited States. These insects live in the groundand construct soil tubes to the timber membersthat they infest. These termites can be controlledby fumigants and toxic saturation of the soil.Preventative measures include concrete curbs orpedestals (at least 12 inches high) to remove thetimber from close proximity to the ground. Sheetmetal shields at the top of the concrete and theuse of wood preservation for timber bearing on theconcrete curb or pedestal are also common preven-tative measures. Dry wood termites and woodboring insects can also be controlled by fumigationand by painting of the exposed timbers with asuitable penetrating chemical preservative. Dam-aged portions of the timber structural memberswill be removed and replaced or supplementedwith additional members if the infestation hasbeen properly controlled.

(2) Fungus Fungus damage to timber inbuildings usually occurs where the timber is al-lowed to be saturated for long periods of time.Wood preservative is a good preventative measure,but in the presence of excess moisture, it will beleached out and become ineffective. The optimumsolution is to exclude the moisture from the insideof the building (e.g., attic spaces with leaky roofs,crawl spaces with water leaks, etc.); provide good.ventilation to the affected areas; and use woodpreservative for timber members in contact withexterior masonry or concrete walls. Damagedstructural members will be removed, replaced, orsupplemented as described above for insect dam-age.

(3) Warping, splitting, or checking. These arecommon problems with older timber structures. Ifthe distress can be attributed to the presence ofexcessive knots, or drying shrinkage of the wood,the timber members will be removed and replacedor supplemented with additional members to resistthe applied loads. If, however, the distress is dueto overstress, differential settlement, or improperconnection details, then these conditions must becorrected before the individual members are re-paired or replaced.

N-,

E-6

TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chap 13, Sec B

APPENDIX F

DESIGN EXAMPLES-STRUCTURES

F-1. IntroductionThis appendix gives illustrative examples for eval-uating and upgrading various types of lateralsystems in accordance with the criteria and proce-dures of this manual.

Fig No.F-1

F-2

F-3

F-2. Use of appendixThe design examples are purely advisory; they arenot intended to place super-restrictions on themanual. This appendix is not a handbook for theinexperienced designer. Neither the manual northe manual supplemented by the appendices canreplace good engineering judgment in specific situ-ations. Designers are urged to study the entiremanual. Following is a listing of the designexamples.

Description of Design ExamplesSample screening and evaluation of a

large military installation.Brick building with concrete framing

system. A 3-story concrete framestructure with brick exterior walls.

Building with steel ductile moment-resisting frames and steel bracedframes. A 3-story building withtransverse ductile moment-resistingframes and longitudinal frameswith chevron bracing.

Building with concrete moment-resisting frames and shear walls. A10-story building with reinforcedconcrete lateral force resistingframes in the longitudinal directionand shear walls in the transversedirection.

F-4


DESICN EXAMPLE F-i

SAMPLE SCREENING AND EVALUATION OF A LARGE MILITARY INSTALLATION:

Purpose. This example is presented to illustrate the screening andpreliminary evaluation procedures described in chapters 2, 3, and 4 ofthis manual. For purposes of this example it is assumed that an A/E firmhas been contracted to perform the seismic vulnerability evaluation of amilitary installation. The A/E's contact at the installation arerepresentatives of the Department of Public Works (DPW).

Description of Facility. Military installation with a large inventoryof buildings. The data base inventory list includes over 100 structuresranging from flag-poles and gate houses to large warehouses and a regionalmedical center. The installation is located in the DM seismic zone 3and the SDG ground motion specification is equivalent to an ATC 3-06spectra with A Av 0.30g. The soil profile coefficient for the siteis type S 2 -

Inventory Reduction. A meeting of representatives of the A/E and the DPWis held to review the data base inventory list, to establish an inventoryreduction procedure, and to visit the site for a general overall visualinspection of the installation. The data base inventory contains dataon replacement costs, year of construction, size of building in squarefeet and number of stories, building identification by number and name,and general usage category. A computer program is able to reorder thedata base files according to (1) largest to smallest replacement costs,(2) oldest to newest year built, and (3) largest to smallest buildingsize in square feet.

a. A list of all buildings less than 500 square feet and all buildingswith replacement costs less than 50,000 are reviewed to determine if anybuildings on the list are categorized as essential or high-risk. Exceptfor the essential and high-risk buildings, all other buildings on thislist are removed from the overall inventory list.

b. A list of all buildings used for housing is reviewed. One- andtwo-family housing, two stories or less, are removed from the overallinventory list.

c. A list of all one-story buildings is reviewed for wood frame andpre-engineered metal construction. Construction type is not listed onthe data base, therefore, a visual inspection of listed buildings isrequired to identify the wood frame and pre-engineered metal buildingsfor removal from the overall inventory list.

d. The visual inspection during the site visit is also used to listsheds and other low-risk buildings that are seldom occupied by persons(maximum occupancy less than 5 occupants). Unless these structures havean essential function, they re removed from the overall inventory list.

Sheet I of 12

Figure F-I. Sample screening and evaluation of a large military installation. (Sheet 1 of 12)

F-2


e. A list of all buildings constructed since 1983 is reviewed.Essential buildings remain on the overall list and all others are removedfrom the list when it appears that 1982 BDK criteria or equivalent havebeen satisfied. When in doubt, structures were kept on the overallinventory list for review in phase I, preliminary screening.

f. A list of the remaining buildings is printed out with the availabledescriptive information contained in the data base in the order of theiridentification number for use in the preliminary screening procedure.

Preliminary Screening. By means of the inventory reduction process thenumber of structures requiring preliminary screening has been reducedfrom over 100 to 74. A meeting of the A/E representatives and usingagency personnel is held to determine the classification (e.g., essential,high-risk, all others) of all structures on the reduced inventory list.The A/E is given access to available design data. This includes the dataretrieval files that list available building drawings, storage files oforiginal building drawings, and additional files for availablecalculations and specifications. Copies of the map of the installation,with building locations, are made available.

a. A table listing the 74 buildings is ade with pertinent availabledata including (1) building classification (essential, high-risk, or allothers), (2) construction category (steel, concrete, masonry, wood, andspecial structures), (3) size, (4) year constructed, and (5) location onthe site.

b. All buildings are located on the installation map. The ap isdivided into geographical zones that include no more than 20 buildingseach. This is done in preparation for the field inspection survey.Preliminary screening forms are filled in with data available prior tothe field inspection (sample shown on sheet 4). The field surveys arescheduled to cover one of the geographical zones each day. Preliminaryscreening formes and other data are prepackaged to aid field inspectionrecord taking.

c. During the field surveys the screening forms and additional notesare made to record pertinent observations or information received by thebuilding supervisor or other building personnel (sample shown on sheet5). One or two photographs of the exterior of the building are obtained,when possible, for nclusion in the report.

d. After the field surveys are completed, the observations arereviewed and compared to data available prior to the site visit. Thefiles of available data are reevaluated to resolve conflicts or to clarifyobservations made during the field investigation.

e. On the basis of the collected data, the buildings are divided intotwo groups: (1) those buildings determined not requiring further analysisand (2) those recomiended for preliminary evaluation.

(1) Buildings not required for further evaluation are listed ina ummary report that includes reasons for making the decision and ivesrecommendations, if any, for further action.

Sheet 2 of 12


F-3

TM 5-809-10-2INAVFAC P-355.2/AFM 88-3, Chop 13, Stc B

(2) Buildings recomended for preliminary evaluation are listedin a summary report that includes a description of the lateral forceresisting system, general condition of the structure, observed hazards(if any), and additional csents.

Preliminary Evaluation. The inventory list for the preliminary evaluationhas been reduced to 50 structures. The capacities of these structuresare estimated by means of a rapid evaluation technique. The capacity ofthe building for an initial major yielding condition and for an ultimateload condition are estimated. By use of the capacity spectrum method,the capacity curve is reconciled with the demand curve of the Q-IIresponse spectrum. An example of the procedure are given in sheets 6through 12. The results of the evaluation of all the structures aresummarized in a report that includes capacities, percent damage, anddamage costs. -

Sheet 3 of 12.

Figure F-I. Sample screening and evaluation of a large military installation (Sheet 3 of 12).

F-4

TM 5-809-10-2/NAVFAC P-355.21AFM 88-3, Chap 13, Soc B

?ULIAT ScawU Ic

ETE ST TA)

tlNSPCD IT S'AFIUILDIIC 0. 53 DATE 51 6

DISCZIPTIV& TITLE h1k'(Current use)

CLASSIFICATION I z e)

AVAILAIILITT Of DEStI DATA

SUILDING DATA:

Number of Stories 3leIght 35

77Af-S

?lIn (Sbov Dimensioas) 49 s 9Z

coiS2UCTION:

Structural Systee SYFA" v* i/ f

loof /47bd~. Prr_ we S cAqw eAchr 5tc

Intermediate oors MC74 Jw 4t - A 7 w . Fnz

Crouad loors 5 dv ifoundations

Interior olle

Ezterior Walle

LATVAL OR M S STING STZM P#2,e

EVALUATION:

General Codition

earthquake Dge Potential

DAMACE OISEVTED:

SOHAWTS:

Sheet 4 of 12


F-5

TM 5-809-10-2/NAVFAC.P-355.2/AFM 88-3, Chop 13, Sec B

rmnrxna SMNIC

UILDINC G Sl n no f DATE //17/u

DESCRIIZ TITLE 4C -&a ~.;z~ 73m/i D/JA4(Current Use) a

CLASSIFICATION CS :AO' 7-4 L74

AVAILABILnI Of DESIGN DATA AS-3Bzii7r PA"AWv'-v4S *.4-4Z"CSG

UILDJIC DATA:

Number of Stories 3igh 52 lan (Sbow Dimenaiona) 62 Y

CONSTRUCTION:

Structural Eystea IA oPc2dCD Cc lrAmrs pgA 115

toof C "R/c4 Xn SiS *wv 3î1 SZater ediate Floors 5*2%eCround Floors S,& oJ Ctkn'e )

ouondationa "A* PA C7/OAV Tc WSX °

Interior Wlls

Eterior Walle VZ4C; k -C,5

LATZRAL FORCE RESISTIMS S =STDI UN2^/'Ji7tJP 8BJCk A1P-si.!$

EVALUATION:

Cemeral Condition 4.oL

Zartbquake Damage potential .4/6

DAMACE OBSERVED: HoveV 6USYia e->D

Sheet 5 of 12


F-6

TM 5-809-10-VNAVFAC P-355.VAFM 88-3, Chap 13, Sec B

BuIl r 1.31 - p A#% 'A Ce. Stp CCsrc.. 14°)

PKLItIAigY EaVLu#r-n#4 ( P| 4 )

fiv: Ct.taix; .t * Or&--4tC (1, 4-2t.) us4qt44 wadw i^,I*o,

Gvcew One kS iqC he a'apec0 v

-t(e-1 - 6weU.- watk A 6D, e SAUtple * I). ., de-PALt g4 .

s b aUt

41, . s

- 1 11i _ _ H~o BAYs P A

- 40Z'

PL*q

TrWSSt5C DtfIM4TEcr

tee~l teot .6 e t.

Sccuot A

:ajewr 61. %V 0 33

I

Cc-.t }JA4f w So t//ltu *sc- F" fae,( w.GL 4-1VZ 6at

Los.Ytauvium .- tIaorwu

T"C-bt slt. 3- Leds e iZ ti. 3 .1oU -74" n#vcts u.

W FE I &Kr!S

Ihtk, 4~r t-', l(VL La~j AlSO 6La.

S; R& "M qmm.t a re 401rsfnut r, s = Iq

itor

6 2 V.=.OPc 4o' l : ' 1. W V S

- .

Sheet 6 of 12

Figure F-l. Sample screening and evaluation of a large military installation. (Sheet 6 of 12)

F-7


BWAICd61t -31 ( C 1oueo)

CAPA(TY TL: tzc--ns-I

-

l

Cot. w 13iI 171 %%S 3ST Is

: 7 3isMyks7 los°,

u l11 4V I S1

r-P y4 14.6 tW~r. It.S r.

7-00' 11 0 - 1= & rl

'10 304o

131 . ',270 Yrf

34.045. i

-. ~-- V - r

$M4P 1ALWib. gm pUt 4 sQ.(I.L0 C*O9'L tU. RID

-___ * ._-c -- w _,_

3Ce ktC u , I _ 7L4,7t Itsa-1q7.zbl Fp &U.TI HATE AT/2S5 fIQS/rI V' a1 gt u4e4R.

3trge, 6VOL109 1. g 4,t4 ivwa t ZV ya O .ec 5-T

I s : 2{/ c -<S

.I'7.. CL. I : I a 6

- : S 312SlI2? -IZE 12124V1r9"00

)

at il0%

De; . uw

tev. Cc1.%31 % JL

7q1.IS

Is7IJ5 SIhe

L.

-14'

-14'

& S 4 0 'a 15 3 _Iva' loll -- I I

.3S7 so Ass&Z. nos

A is t DS 'aI \. 0. o"qA|f I--L 1^3 I .I, *

lets& M £1 b l re fbj/ es . 4 ~v rr j ISLI D A S

Sheet 7 of 12

Figure P-l. Sample screening and eatuation of a large military installation. (Shet 7 of 12)

F-8

TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, ChCp 13, Sec B

'Bu.dcJin I3I, CaluitU T-sie-Ve PDt. (et.)

H40 ls F14 F (w-- a-elee~f+., ) a^nss)*. vit- -- '/z V) E ,) : -sq fecd.

C~tck F:11 IO$^* ' *05 ?6[ie r-&^Coi*ra'h " Lra 4 C as

rxv r4%j I at P o At1

T V- 1.ih ¶La lw &&4 4 ' eSC4 aiu .. 14, ) 4 ledLm.

" 1, U-6 IT 2 V ,25Z,-1 3#23

lbtk ~ 6 'r ~ v~zseurv.-Wr C ISAAA .

* G,tne, W-24 1 -: :lloo £'176

* M.t t $t 6 -I ' 28 4 i 6V A{

* IGewdi8 WAS B- C c . l; i *IpatdA4 25 ( 40' t'.i.. r IOIa0 /A - I t ,

FhI o to.&t,::t LD4 wa |. d 4. in.w d1ii LL

kok,&J 'ell qo -¢ g.Tea:m * A1_lt~ r 2g -40 m, 43 >1.CO.* #rAof *ttes wit Ai4 a s5be cdbaU.L

TV~5wS CCTY SMngy - (s 5 /tLt hMIL KR OC Si S.

( ) ts 144 ("s) EST) l s C' ck

Fed~c Y'VD OA . 1.80 1.S WU5 IA!' o.Ks o-u'Zu YP 0.e51 IO 1.2l I I I-VS -g di 0.6sW.rTwi. 1 IzI o.4 .1 t 4.V 0.61 OiS.t&-04IcsU

Sheet 8 of 12

Figure F-1. Sample screening and evaluation of a large military installation. (Sheet 8 of 12)

F-9

-


1AI'cjT 131 (jT)

CAPAC 1 Y 19 1LOt rLa1TD I AL DIRC.T1oN-

r~~~~ _, -V. . ,~ _6 -.. ,__.. P,.

i_ i_ ;_ ix I 3oi |> 1t5'1 >.<U --7--T - 15ZE1 ! i>_ NI1b w-gi

!I oe " v. "4 V_ - L IC,. S

.4CLEVA1SUA

Aswis.tets Uftsed *t fil S1 1A) r,4 iura4 ia low oo to *rmee Ikdeml "s2. Low r*f S&oohm ko-tt tUH brc.&4 o rarnte-

frow. "fer"w- -rt.& 1 4I eoferpr ca(ume'3. Tdeveer lau4 safmlr fmA Lr&ed c a tpr

{roma steiid. s W 4 4caumnS4. tetior gtwo"i fed mA i &. U&%ttS E..*noe C . gegliglt for I.LA'.. itttlC,'.

tc.,s f;VdI wtS oePig ¢

CASEI All pezes iaka% I 4 sis ,rf X-bq,s- -is c&Im SAA * o W )

p\r,^ Wvebz~eff- fX,.cs (to.iesaCASE U CAsaLFIASICAZS W 4)xlWaw .11 VCS&S-1t.4y3 % ,*.A ofm,. (weAk d1.trxf.

)

DIA4&&QArL. SACM 3 3 I/M

L- Ti 1* 4a' 42.1 &mt JoLs i at eadew Lx- 21.3'rj ' O.C.bV, s ; 1.o0 6 Wr 0.i.s, A .1.3 a"

r, f. L 2.3- V uri.1; 4, a 37 &I ~ *,,,4...P..

No ComP?"S1,lo CAfCiTY '

Sheet 9 of 12

Figwe F-I. Sample screening and evaluation of a large military installation. (Sheet 9 of 12)

F-10


'BI.1(AI- I's^ 13 1, C-pac La. ^bi(Cont)

CAE I BrgAsc Wegdawvgs i e o °l,

- 44'

.Cacc cokwnc.-F 4 ues kJ7Is (-sv.e SOZ-t)

Aisc. *q.L(sg soole 31ec- IYo-oLL c .,OZ /k

ramp e<t~c.r ti 17 tiw)scE -r Is. /'5

Fce, .a 4 1 5- 57 S 6S5

V,,,LO t6 4r&,.s if 57.5 S 345 CASE :.:. c4^ ~ tn 4 ,dzo

2.w 11 - Wtlo wt33 c t ?3,.Scrt5 SJ,, ha LrnA'mb24 11 - W it 4s 34.iwV *a .a .32 f

UP C4 s@ r g &SC9@4*rI V s<st3W.s "

VA Z.- 4 4 443I.- 16S;

IN

-ss42> X .sE/n )^- ss t] - o No.0 ' 0.0

S 3~z 3--o15 "2 ~ ^.X4CASC XC3,^za,-'4

Sheet 10 of 12

Figure F-l. Sample screening and evaluation of a large military installation. (Sheet 10 of 12)

F-1I


3i&AAO 131, C&p&c11t L wv. Die- (cwo P.oT)

R8c1 CL 6 rLt.^ 4a1 gt4 - Ur ai S

BRACS' O (0 " 57S I - 1 I

CoLUMes ". .63YI.74' " 94 .,

Fersi Ytev Wten lertes re {kkhj '345 it Az0.60"1

Columns art rtslI&I 'I0r4163' &7 SL"'t

* Co5^; Sl 1 \5 - 401 @76 A-46

Ss~ ra1I A, V3 4;1, re.sâ . .c{aJ i:s 151.

* 2/3 (34rS) IIS = 2 4K 6! e 060'9I

-~~~I Cowtens0.9 X 1°/45) L3 84 k

u= 3 I' & A IL

fATIMATE ArLf. fiPAZC FL

fw YiED t HtS, 0.10 Q O.

3 8' 0-11 01.9 s4 o.01 qo 1O1 2.7 IL

1' -.1 1.7 -7/1.714 4 oar -L.Assumr1 5143S4.05-122.7

Lt; ITUD(L)Af e-kACO SntAPLY (C- q62 W

VI Cs &dt AUR 'Pr oc Sa T(V/*t) UALv (gt) cm ANve PR ' ZO;E

rft Y 401 00 0.6W 1.2t ofqo 0.% a03 0,J ,ftF fl. 3 41'1. 0.\ I.? IoS OAO° 1%4.. of*o o.85s.Uvr III" 0nJ .7 S 1.* 0.4 4 o.173 1.11 SA%0158J

)

Sheet 11 of 12

Figure F-I. Sample screening and evaluation of a large militay installation. (Sheet 11 of 12)

F-12

TM 5-809-10-2INAVFAC P-355.2AFM 88-3, Chop 13, Sec B

CA PAC ITY T TR S VERSE LO N& Ir0.8 IV M

SPEcTA 5 0.441 OS aoq 0.2 3 0.20 0.0 q?_ T 0.5b 068 08Z 0.465 0.8s 2.13

NtcfL SCcrgA -A0.25

Dri,"^ 3X 7 SIEEL BULOI4 * 131

L.oo

Sol

(9)Tkok,.ram

r 3 . 4CA

K7 %~7X do

0.50

M.IS

0

D w4A e ).-e^tM A TtUS'

O. ZF 52 .0. 125 0

. 0. 063 0 I ~S

. . . .

Lo tic T..> 100o 4.

5go/ 010

T corz~uc1,4

33l0

.

owl &.an wfI LuzcmeS 5Y.

Sheet 12 of 12

Figure F-1. Sample creening and evaluation of a large military installation. (Sheet 12 of 12)

F-13

TM 5-809-10-2INAVFAC P-355.2AFM 88-3, Chop 13, Sec B

DESIGN EXAMPLE F-2

BRICK BUILDING WITH CONCRETE FRAMING SYSTEM

Description of Structure. A 3-story communications building built circa1905 with vertical load carrying concrete frames and exterior unreinforcedbrick masonry walls. The floor and roof construction is comprised ofreinforced concrete slabs and beams. The building is supported on concretepile caps and timber piles. The structural design concepts are-illustratedon sheets 2, 3, and 4.

Construction Outline.

Roof:Built-up roofing.Reinforced concrete slabs, beams, and girders.

2nd and 3rd Floors:Reinforced concrete slabs, beams, and girders.

1st Floor:Reinforced concrete slab-on-grade.

Foundation:Reinforced concrete tie beams and pile caps supported on timberpiles.

Exterior Walls:Unreinforced brick masonry with terra cotta facade.

Partitions:Clay tile walls and wood stud walls with gypsum board sheathing.

Background. As a result of the inventory reduction and preliminaryscreening process the building was included in the list of buildingsrequiring a preliminary evaluation. On the basis of the preliminaryevaluation (sheets 6, 8, and 9), upgrading concepts will be developed.A summary of the Acceptance Criteria and the determination of the SiteResponse Spectra are shown in the sheets 5, 6, and 7.

Sheet. 1 of-25

Figure F-2. Brick building with concrete framing system (Sheet 1 of 25)

F-14

TM S-809-10-2NAVFAC P-355.2VAFM 88-3, Chop 13, Sec B

EXISTING FLOOR PLAN

Sheet 2 of 25

Figure F-2. Brick building with concrete framing system. (Sheet 2 of 25)

F-1 5

TM 5-809-10-2NAVFAC P-355.2IAFM 88-3, Chap 13, Sec B

0 0 0. I I I I L

(0

I I I

__ _ _ . 1 I . .

i 1 1 . I I 1

l vt/i-'-'-4

I ew "w~~~~~~.

4 4. 4.',, u

EXISTING EXTERIOR ELEVATION

Sheet 3 of 25


F-1 6


W71M

ri -

TYPICAL TRANSVERSE BUILDING SECTION

Sheet 4 of 25


F-17

TM 5-809-10-2/NAYFAC P-355.2VAFM 88-3, Chop 13, Sec B

The Acceptance Criteria for the seismic resistance is that presented forthe post yield analysis for EQ-II, Method 1 (refer to SDG paras 4-4 and5-5).

Classification:

Loading Combination:

Ultimate Strength Capacities:

Inelastic Demand Ratios:Nonductile Conc. Frames

ColumnsBeams

Reinf. Conc. Shear WallsSingle Curtain Reinf.Double Curtain Reinf.

Essential

DL 0.25LL + EQ

ACI 318 Strength Design

1.001.25

Shear-i.10, Flexure-1.5Shear-1.25, Flexure-2.0

Material Properties:Concrete

Reinforcement

Unreinf. brick masonry

Story Drift Limitation:

fc ' 4000 psi(Nev)fc' 3000 pi(Exist)Fy - 60 ksi(New)Fy - 33 ksi(Exist)Em - 1000 ksi(Exist)

0.006 x Story Height )Sheet 5 of 25


F-1 8


Site Response Spectra. The site response spectra are developed inaccordance with the procedure in Chapter 3 of the SDG:

Building Classification: Essential Facility

Ground Motion Spectra: ATC 3-06 Hap Contour Level,As AV 0.10

Soil Classification: Si - 1.5 (Type S3)

Earthquake IDamping 5, D.F. - 1.00 SDG table 3-7)Aa = A = 0.04g (Design Ground Motion, SDG table 3-4)Sa D.F. (1.22AVSi)/T - 0.073g/T less than D.F.(2.5)Aa 0.10gmax

Earthquake IIDamping - 10X, D.F. - 0.80Aa AV 0.12gSa D.F. (1.22AvSi)/T 0.176g/T less than D.F.(2.5)Aa - 0.24g max

EQ-II/EQ-I 0.24/0.10 - 2.40

The resulting spectra are shown on sheet 7.

Preliminary Evaluation. The lateral force resisting system primarilyconsists of unreinforced brick masonry piers and walls, partially confinedby the concrete frames. The concrete frames are capable of only a minimalamount of lateral force resistance as there is very little continuity inthe reinforcement at the column-beam joints. Since the existing wallswould be required to resist most of the seismic force by relative rigidity,the existing concrete frames will be ignored in the preliminaryevaluation. A rapid approximation of the seismic demand is made byassuming that the demand spectral acceleration (Sa) for the first modeis 0.24g (i.e., T less than 0.7 sec) and that the base shear coefficient(CB) - 0.865 a 0.21g (CK- 0.86 per SDG para 5-3a(2)(c)). The seismicforces will be distributed to the various stories in accordance to thestatic design provisions of the BDM. The capacity of the existingstructure will be approximated by calculating the average shear stress(story shear divided by the total net wall area in each direction) foreach story. See sheets 8 and 9 for this preliminary evaluation. Thestructural deficiencies identified were the non-conforming moment-resisting concrete frames and the unreinforced brick masonry walls inboth shear and flexure. Results show conclusively that the building doesnot satisfy the acceptance criteria. Therefore, a detailed structuralanalysis of the existing as-is building is not required. Upgradingconcepts will be developed and the acceptance criteria of the upgradedstructure will be confirmed by a detailed structural analysis.

Sheet 6 of 25


F-19

TM 5-809-10-2INAVFAC P-355.2AFM 88-3, Chap 13, Sec B

DESIGN RESPONSE SPECTRA FOR EQ-I AND EQ-Il

0.25

0.20

saws 0.15

0.10

0. 05

0.00 0.0 1.0 2.0 3.0

PERIOD, SECONDS

4.0

PERIODEQ 0.0 730 1.0 1.25 15 2.0 3.0 4.0

52 Saog. .04 .10 .073 .058 .049 .037 .024 .018

II LO S, ,g .12 .24 .176 ,141 .117 .088 .058 .044

S4 #n 0 1.25 1.72 2.16 2.58 3.45 5.11 6.89

* SPECTRAL DISPLACEHEIT SSa(TtW) 2g

Sheet 7 of 25

Figure F-2. Brick building with concrete framing -system. (Sheet 7 of 25)

F-20


RAPID EVALUATION

Longitudinal Direction

Lateral force resisted by two exterior walls.

Total length of walls - 2 x 186' - 372'.

Windows reduce effective length by 1/3.

Effective Length - 2/3 x 372' 248'

Assume 18" brick wall at 15 psi shear strengthat 50 psi shear ultimate(to be confirmed by tests)

At 15 psi V 248' x 12 x 18" 0.015 - 803kAt 50 psi V - 248' x 12 x 18" x 0.050 - 2680k

Calculated Weight: 10,000k

Equivalent to 17#/cu ftor 290#/sq. ft

Estimate Capacity

I803

CB - yield? 0.08g10,000

2680- ultimate 027g

10,000

NOTE: Typical pier width/height ratio - 1.20, therefore assume sheargoverns.

DEMAND of earthquake: Sa - 0.24g (Sheet 6)CB c 0.86 Sa - 021g

Requires about 40 psi capacity (e.g., (0.21g/0.27g)S5O).

If strength is confirmed by tests, the longitudinal direction couldwork if connections are acceptable.

W CECK THE TRANSVERSE DECTION

Sheet 8 of 25

Figure F-2. Brick building with concrete framing system. (Sheet S of 25)

F-21


RAPID EVALUATION (continued)

Transverse Direction

Lateral Force Resistance

Two exterior brick walls: 44' x 2 - 88'

Vext - 88' x 12 x 18" 50 psi

Two interior hollow clay tile

Vint - 2 x 50' x 12 x 8" x 20 psi

Total resistance

effective length

95 0k

- 19 2 k

- 1 1 4 2 kips

1142Estimated capacity: V/W - - 0.114

10,000

is less than the demand CB - 0.21 (Sheet 8).

Conclude: Weak in Transverse Direction

Even with liberal allowances for material strength, resistanceabout 1/2 demand.

Sheet 9 of 25 )-I

Figure F-2. Brick building with concrete framing systemr (Sheet 9 of 25)

wF-22


Development of Seismic Upgrade.

Structural Upgrading Concepts. Three concepts were considered:

1. Install reinforced concrete gunite against the interior faces ofthe exterior unreinforced brick walls and add new interior cast-in-place reinforced concrete walls.

2. Install vertical structural steel plate panels as infill wallswithin existing transverse interior concrete framing and usediagonal steel braces for the longitudinal direction.

3. Construct exterior buttresses to give lateral support to theexisting building.

No. 1, above, was selected as the recommended concept. Plans,elevations, and details are shown on sheets 11 through 17 and adiscussion on the analysis is contained on sheet 18. For concept No.2, steel walls and bracing, it was considered to be difficult to obtainsatisfactory connections between steel and concrete because of thehigh force levels. For concept No. 3, exterior buttresses, apreliminary cost comparison indicated that it would not be as costeffective as concept No. 1. Also, concept No. 3 would distract fromthe historic significance of the building. A disadvantage of conceptNo. I was the blocking out of existing windows; however, it wasdetermined that this would not be detrimental to the planned use of

f the building. It should be noted that, if it were mandatory to minimizeon-going operations in this building, then the additional costs ofconcepts Nos. 2 or 3 might be justified.

Sheet 10 of 25


F-23


)

FLOOR FRAMING PLAN

Sheet 11 of 25

)Figure F-2. Brick building with concrete framing ystem. (Sheet 11 of 25)

F-24


SYM. ABT.

*1 A

SECTION A-A SECTION a-a

Sheet 12 of 25


F-25


DRILLED HOLES IN SLABFOR PLACEMENT OF CONCRETE& REINF. DOWELS

EXISTING CONCRETE

NEW REINF. CONCRETE MULLION

)SECTION b-b

SECTION B-B

Sheet 13 of 25


F-26

TM 5-809-10-2/NAVFAC P-355.2VAFM 88-3, Chap 13, Sec B

INES C

LINES & 4

Sheet 14 of 25


F-27

TM 5-809-102/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

ROOF

3/4 o RILL-THRU* ANCHORS @ 3'-0"

O.C. EA. WAY

!-

CL

8" GUNITE LAYER 1 Il

18" AT WINDOWS!I * 1

I 1'xl' TYP.II -l HAUNCHi III1 l

11 11 11 i1 11Z 21

'I tI I, 1. 1 1

REMOVE BRICKII II' ITO EXPOSE REINF.

C CONC. COL. DRILLIi I'#6.DOWELS THRU

-1COL. @ 12" __ . .

PARTIAL PLAN AT

st & 2nd FLOOR

)

DRILL INTOEXIST 4 TIEBEAM

SECTION C-C

Sheet 15 of 25


)

F-28


LINES A, B D, E, F G & J

Sheet 16 of 25


F-29

TM 5-809-10-21NAVFAC P-355.VAFM 88-3, Chap 13, Sec B

I

.

LINES C H

Sheet 17 of 25

Figure P-2. Brick building with concrete framing system (Sheet 17 of 25)

F-30


Detailed Structural Analysis to Confirm Concept. A detailed structuralanalysis was not necessary for the existing structure because of thenegative results from the preliminary evaluation. However, a detailedanalysis is now required to determine if the recommended concept willsatisfy the acceptance criteria outlined on sheet 5. A modal analysisof the modified structure was made with the aid of a general computerprogram for static and dynamic analyses of frame and shear wall three-dimensional buildings for both the transverse and longitudinal direc-tions. The program assumes rigid diaphragms and the roof and floordiaphragms of this modified structure essentially met this assumption.Sheets 20 and 21 indicate the SRSS of the dynamic modal responses fromthe computer output. Sheet 22 indicates the evaluation of the SRSSresponse of some representative structural elements and sheets 23 and 24contain stress checks of selected elements for compliance with the cri-teria.

Torsion Forces. Due to the symmetry of the structure lateral load re-sisting system there is no "calculated torsion." The "accidental tor-sion" is the story force times the nominal eccentricity of 5 percent ofthe maximum building dimension. The forces due to torsion were calcu-lated by applying a torsional moment in each story equal to the seismic(SRSS) story shear times the "accidental" eccentricity (0.05 x 186feet). The resulting member responses from this analysis were added tothe translational member responses (SRSS) of the dynamic analyses.

Foundation Ties. The DM (para. 4-8a) requires that pile, caisson, anddeep pier footings in seismic zones 2, 3, and 4 be interconnected byties. In this building, the existing foundation ties are near the topof the large piers (see sheet 4 of 24) and provide questionable re-straint to the timber piles. The seismic upgrading modification pro-vides a good tie, in the plane of the new walls, for the piles on linesC and B. Te significant cost and disruption of the existing buildingrequired to install new tie beams throughout the building may not bejustified if it can be demonstrated that the seismic forces from EQ-IIcan be transmitted to the ground with the existing tie system or bypassive soil pressure on the existing piers.

Sheet 18 of 25


F-31

TM 5-809-102/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

Results of the Confirmation Analysis. The modified structure meets allthe acceptance criteria requirements for EQ-II forces except for possiblythe capacity of the timber piles to support the additional loads from thenew concrete walls. The capacities of the timber piles to meet therequirements for the new dead load plus live load loading criteria willneed to be re-evaluated. As a result of the detailed analysis it wasdetermined that the unreinforced brick masonry walls that were not beingreinforced with gunite were deficient for seismic forces normal to thewalls. These walls will either be anchored to the new concrete walls orwill be provided with new vertical concrete or steel mullions betweenexisting concrete columns for additional lateral support to meet the EQ-IIacceptance criteria. Shear and flexural stresses for seismic forcesparallel to the walls were found to be within the Acceptance Criteriaafter strengthening. An alternative modification concept was studiedthat provided for the anchoring of all exterior unreinforced brick masonryend walls to new reinforced concrete gunite walls placed against theirinterior faces in lieu of constructing the new concrete walls on Lines Cand H and the additional vertical concrete mullions. This concept wasrejected because it resulted in unacceptable shears in the floor and roofdiaphragms and excessive overturning forces for the end walls in thetransverse direction. The recomended concept could have been implementedfor the entire length of the longitudinal walls thus eliminating thevertical mullions, but it is more cost effective to provide new gunitewalls as required for shear resistance and new concrete mullions in theremaining portions of the existing longitudinal walls.

Sheet 19 of 25


F-32

TM 5-809-10-2/NAVFAC P-3SS.2VAFM 88-3, Chap 13, Sec B

MATHE.MATICAL MOZDEL - TRANSVERSE DREC"IO

2

R~ ~~9. 1TL t 5. 36 Kip-Sec /Ft.

3 l3 114.64 ip-Sec /Ft.

2 s H2 119.88 Kip-Sec 2Ft.

Tl " 0.20E Sec., T 0.076 See., T * 0.045 Sec.Se. 2 3.3

EQ II - MTRUCTURAL RESPONSE, TRANSVERSE DIRECTION - SRSS

LEVEL | STORY LOAD** STORY SHEAR [ DISPLACEXENT ( STORY DRIFT*No. Fx - Kips V - ips cr- Feet | - Feet

3 875 875 0.012 0 006

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ I _ _ _ _ _ _ _ _ _ _ _ _0 .1 2 0 *

2 809 1449 0.005 0.004_ _ _ _ _ _ _ I _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _0 .1 0 5 *

1 565 733** 0.002 0.0902

^ ".v~>., . ^t^ ^, _ hA .,. ~ttP ^0_ A90'

w FAi1ln "LLmW'ALL

* FX E)BeIq I1 519Y PII a .006H

,:* CB = V +, W = 0.174

Sheet 20 of 25

Figure F-2. Brick building with concrete framing Aystem (Sheet 20 of 25)

F-33

TM 5-809-10-2NAVFAC P-355.2AFM 88-3, Chop 13, Sec B

MATHEMATICAL MODEL - LONGITUDINAL DIRECTIONl

2R MR * 75.36 ip-Sec /Ft.

r4 ~~~~~~~~~~~23 H3 114.84 ip-Sec /Ft.

22 M2 119.88 ip-Sec /Pt.

1 .7-7 7r -T= 0.222 Sec., T 0.068 Sec. T a 0.040 Sec.

)

EQ II - STRUCTURAL RESPONSE, LONG. DIRECTION - SRSS

LEVEL STORY LOAD** STORY SHEAR DISPLACEMENT STORY DRIFT**No. Fx - ips V - ips - Feet- - Feet

3 873 873 0.014 0.120*

0.0042 804 1524 0.008 0.105*

1 577 1859r: 0.003 0.003_____ ____ ____ 0.090*

* MAXIMUM ALLOWABLE

** F = Ek'xA I

4 I [('^ m5

EQ II STORY DRIFT 0.006H

*** CB = V . W = 0.186

Sheet 21 of 25

Figure F-2. Brick building with concrete faming system (Sheet 21 of 25)

F-34

- TM 5-809-10-2/NAVFAC P-3SS.2/AFM 88-3, Chop 13, Sec B

EQ II SRSS ELEMENT FORCES - TRANSVERSE DIRECTION

v (Kips) M (Ft-Kips)

422

7880

690

19,680

84331.S72

WALLS C & H

EQ II SRSS ELEMENT FORCES - LONGITUDINAL DIRECTION

V (Kips) M (Ft-Kips)

218

4365

381

10,812

465

_ ________________ 17,422

WALLS ON LINES 1 & 4

(2 EACH LINE)

Sheet 22 of 25


F-35


"ACCIDENTAL" TORSION FORCES

The "accidental" torsion is the story shear, V , times the nominaleccentricity of 5% of the maximum building dimension:

Mt = V x 0.05 x 186' = 9.3 Vx x

The story relative rigidity (K) of each wall line is obtained fromthe computer analysis.

Torsion Shear = K2 x 93 VKd2 x 9.3 (

Distribution of Forces (Frames neglected)

Roof Level

WALL REL.LINE K

C 0.94

d

52

Kd

48.9

Kd2

2542

DIRECTSHEAR

O. 50VT

TORSIONALSHEAR

O.0 6 7 VT

H 0.94 52 48.9 2542 0.50VT 0.067VT

1 1.00

4 1.00

29 29.0 841

29 29.0 841= 6766

3rd Floor Level

WALL REL dLINE K

C 1.06 52

H 1.06 52

1 1.00 29

4 1.00 29

2nd Floor Level

WALL REL dLIE K

C 1.44 52

H 1.44 52

1 1.00 29

4 1.00 29

Kd

55.1

55.1

29.0

29.0,E=

Kd

74.9

74.9

29.0

Kd2

2866

2866

841

8417414

Kd32

3894

3894

841

0. 50VL

0. OVL

DIRECTSHEAR

0 * SOVT

O. 50VT

O. 50VL

0. 50VL

DIRECTSHEAR

0. 50VT

0. 50VT

O . 50VL

O. 5OVL

0. 040V L

O.04OVL

TORSIONALSHEAR

0.069VT

0.069VT

0 . 036VLO.O36VLO0.036V L

TORSIONALSHEAR

0.074VT

0 . 074VT

0.028VL

O.0 2 8 VL

)

29.0 841= 9470

Sheet 23 of 25

Figure F-2. Brick building with concrete faming ystem (Sheet 23 of 25)

F-36


ELEMENT STRESS CHECK

Wall on Lines C & H at 2nd floor level

Moment

MD:D EQ II ForcesAccidental Torsion:- 19,680 x 0.069/0.50

M : 12,503 ft-kips

IDR: 22,396 + 12,503 = 1.79< 2.00

19,680 ft-kips= 2,716 of

22,396 ft-kips

Shear

V:D EQ II Forces:

Accidental Torsion: 690 x 0.069/0.50 =690 kips95 785 kips

V:U

IDR:

1243 kips

785 + 1243 = 0.63< 1.25

Wall on Lines 1 & 4 at first floor level

Moment

:EQ II Forces

Accidental Torsion: 17,422 x 0.074/0.50 =17,422 ft-kips2,579 it @1

20,001 ft-kipsM :

UIDR:

10,088 ft-kips

20,0Ol - 10,088 = 1.98 < 2.00

Shear

VD-EQ II ForcesAccidental Torsion: 465 x 0.074/0.50 =

V : 802 kips

IDR: 584 - 802 = 0.67< 1.25

465 kips69 kips534 kips

Roof Diaphragm

Moment 2MD u(875 kips *- 186 ft) x 41 -.-2 = 3950 ft-kips

Mu = 4348 ft-kips

IDR = 3950 4- 448 = 0.91< 1.50

ShearVD = (875 kips - 186 ft) x 104 - 2 = 245 kips

Vu = 292 kips

IDR = 245 -292 = 0.84 < 1.10

Sheet 24 of 25


F-37



Unreinforced Brick Masonry Wall (12" Min. Thick, S a= 0.36; Max Span = 7')

Moment

MD: (120 psf x 0.36) x 7* 8 = 263 ft-lbs/ft

M : (1.6 x 7.5 psi) x 288 in /12 = 288 ft-lbs/ftU

IDR: 263. 288 = 0.91 <1.00

Shear

VD: (120 psf x 0.36) x 1.15 x 7' 2 = 173 lbs/ft2

V : (1.6 x 7.5 psi) x 144 in = 1,728 lbs!ftU

IDR: 173 1728 = 0.10 < 1.00

Sheet 25 of 25

Figure F-2. Brick buidng with concrete framing system (Sheet 25 of 25)

F-38


DESIG EMPLE F-3

BUILDING WITH DUCTILE STEEL MOMENT FRAMES AND STEEL BRACED FRAMES

Description of Structure. A 3-story hospital building withductile moment-resisting frames and longitudinal bracedstructural steel. The building is the same as described inexample A-3 and SDG example E-3 and shown on sheets 2 and 3.

transverseframes inBDM design


Roof:Built-up 5 ply.Metal decking with

insulation board.Suspended ceiling.

2nd & 3rd Floors:Metal decking with concrete fill.Asphalt tile.Suspended ceiling.

1st Floor:Concrete slab-on-grade.

Exterior Walls:Non-bearing, non shear,insulated metal panels.

Partitions:Non-structural removable

drywall.

Original Design. The structure was designed in accordance with theFebruary 1982 edition of the BDM. It is an essential building I-1.5)in Seismic Zone 3 (Z-3/4) as designated in the SDG, Figure E-3, Sheet 1.A summary of the seismic design force coefficients follow.

Seismic Zone 3Hospital buildingDuctile frame/braced frameSoil periodBuilding period

TransverseZ - 3/4I - 1.5K - 0.67T - 1.0 secT 0.69 secCS - 0.116ZIKCS - 0.087

LongitudinalZ - 3/4I - 1.5K 1.0Ts - 1.0 secT - 0.3 secCS 0.140ZIKCS 0.157

Background. The building is classified as an essential building and wasdesigned in accordance with the current BDM. Thus, it was decided thatthe preliminary screening and the preliminary evaluation would not benecessary because the building would be placed on a high priority listingfor a detailed structural analysis. The detailed structural analysis forthis building, which is covered in Figure E-3 of the SDG, is summarizedon sheets 7 and 8.

Sheet I of 23

Figure F. Building with steel ductile moment-rmisting frames and steel braced frames. (Sheet I of 23)

F-39

TM 5-809-1O2/NAVFAC P-355.2AFM 88-3, Chop 13, Sec B

20'yGYAT%^ Q.l @ p* g.PO-

-~~~~~~~~~~~~~ - - ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~.-

e.r- r

p~~~~~, 1 I

1- Wi~i I-it *j. V £1 -4 I a x

f _ _ _ _ _ _ I_ _ I_ _ _ _ _ _ _ _ _ _ _ , _ _ _ _ _ _ _ _ _ I _ _ _ _ I

'. U_ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ I _ _ _ _ _ _ _ _ _ _ _

0 0ROOf- PA)J

G~A'S 1A0C I !!>,YS eP J O' / 94e 0'

'-- -rANVSVkRSrI "AM"

0I-- I I

L0/AZ8rI1,1AIA I--,ARAC INC2v3°Fto t 6z

* tAn-rS Z-A( SIZ- Ar z,- LOO

WI",

JO I 7t.A3 SVRS E

J0to 1 J I W te- 300

a-. i W/dTAO WG , W4O • Ž __|

Wds4O l W/dAa -K>IX IA - - --.. . - - -

554 5 L AfG/tEh/NA44 RACJI. AOAMIS

SO UrW d (VA TrION (IoRTv Z 4EV. SIM. OAP.M14N)

Sheet 2 of 23

Figure F-3. Building with steel ductile moment-resisting frames and steel braed frames. (Sheet 2 of 23)

F-40

TM 5-809-10-2VNAVFAC P-355.2/AFM 88-3, Chap 13, Sec a

LOAI3$.Roor:

6-P1 y ROOrINSP/MrSULArToivS(574 JoCrSrrt. PUt INSSTel 6ERSCEI4NC

MtSCUdSANEO&S104AD LOAO

A0b OIR SeISMIC:PAl? T/rONS

s=6. O le. . X.

3. 7

= 10.0

= 25.7RS= 25. 7S.,f

2 UD 3R FOORS:FINIShSreel DECKcoNReirE sMC5TEEL &4rAMSSTEE GI1in#1Ee COUMNS.R 4r Tbo1irS

CEl/NGMISCELZ ANAOUSOCAO LOAP

LJVf 4OAD

= L.OPIF= --U I0= q

- .5.= zo- $AOUI.0= t-s R5F

= 0.OP$s'' J 0

TOTAl FOR SC/SM/C = 3S 7 SA

* *10-I

* 4

�e1

¢ ( D ,c3

1-1 .8 6 I4E.

XI

L /iNE /}.4,/ 7

rRANts vdse oc/L memomeNT Rtvs rTIN PAA41

Sheet 3 of 23

Figure F-3. Building with steel ductile moment-resisting frames and steel braced frames. (Sheet 3 of 23)

F-41


Acceptance Criteria (para 5-2). The acceptance criteria for existingbuildings are those presented for the post-yield analysis for EQ-I inthe SDG with latitude allowed under certain conditions.

Conforming Systems and Materials. The systems and materials are incompliance with the requirements of the BDH; therefore, the EQ-IIresponse spectra may be reduced by as much as 15 percent (para 5-2a).

Method 1. Elastic Analysis Procedure (Refer to SDG paras 4-4c and5-5a).

Classification: Essential Building

Loading Combination: DL 0.25LL EQ

Plastic Member Capacities: 1.7 AISC allowable stresses, typ.(1.4 for shear stresses)

Inelastic Demand Ratios: DMRSF beams" columns

Braced Steel I.I of

Is of

to of

of It

Frame beamscolumns

I dia. br.f K-braces

" connector

2.001.251.501.251.251.001.001.25Metal Deck Diaphragm

0.010 x Story Height i )Story Drift Limitation:

Method 2. Capacity Spectrum Method (Refer to SDG paras 4-4d and 5-5b).If the acceptance criteria of Method 1 are not satisfied, the structurewill be analyzed in accordance with Method 2 prior to developing aseismic upgrading concept.

Sheet 4 of 23

Figure F-3. Building with steel ductile moment-resisting frames and steel braced frameL (Sheet 4 of 23)

F-42

TM S-809-10-2INAVFAC P-35S.2/AFM 88-3, Chap 13, Sec B

Site Response Spectra. The response spectra for the site, which are usedfor both the detailed structural analysis and the upgrade concept, weredeveloped in accordance with procedures in Chapter 3 of the SDG and arethe same as those used for SDG Figure E-3.

Building Classification: Essential Facility.

Ground Motion Spectra:

Soil Classification:

hTC 3-06 Map Contour Level,Aa Av = 0.30

Si 1.2 (Type S2)

Earthquake IDamping Aa = Av Sa = D.F.

Earthquake IIDamping Aa AvSa = D.F.

3%, D.F. - 1.17 (SDG table 3-7)0.14 (Design Ground Motion, SDG table 3-4)(1.22AvSi)/T 0.24g/T less than D.F. (2.5)Aa = 0.41g max

7%, D.F. 0.90.35(1.22AvSi)/T 0.46g/T less than D.F. (2.5)Aa = 0.79g max

EQ-II/EQ-I 0.79/0.41 - 1.93


Sheet 5 of 23


F43


DESIGN RESPONCE SPECTRA FOR EQ-I AND EQ-II

0.9

0.8

0.7 X EQ-II, 3=7

0.6 I1

S 99 0.5-1

0.4

0.3- \ \ EQ-I

0.2 r\

0.1

0.0 I

PERIOD, SECONDS

PERIODEQ - -- - - - -EQ XP I0.0 .568 .80 1.0 1.5 2.0 3.0 4.0

I 3 S ,g .14 .41 .300 .240 .160 .120 .080 .060

II 7X Sag .35 .79 .576 .461 .307 .231 .154 .115S in 0 2.66 3.61 4.51 6.76 9.04 13.57 18.01

SPECTRAL DISPLACEMENT S (T/2r) 3d a

Sheet 6 of 23

Figure F-3. Building with steel ductile moment-resisting franes and steel braced frames. (Sheet 6 of 23)

F-44

TM 5-809-10-2/NAVFAC P-3S5.VAFM 88-3, Chap 13, Sec B

Detailed Structural Analysis The structural evaluation of the existingstructure was covered by the EQ-II analysis of SDG Figure E-3. The resultsare summarized as follows:

Transverse Direction (Moment Frames):

Method . The inelastic demand ratios for the first floor columnswere over 2.0. This is greater than the 1.25 that is allowed. Evenwith the 15 percent reduction in demand allowed for existing buildings,the allowable limits are exceeded. Drift limits were also exceededby more than 15 percent.

Method 2. The capacity spectrum method was also used in the evaluation.The results are shown on sheet 8 for the full value of the EQ-Ispectrum. Even with the 15 percent reduction in the spectrum thestructure does not satisfy the acceptance criteria.

Longitudinal Direction (Braced Frames).

Method 1 The diagonal members in the chevron (K-braced) braced frameswere overstressed by almost a factor of 3 for EQ-II; thus it will notsatisfy the acceptance criteria.

Conclusions. The conclusion of the detailed analysis is that neither themoment frames in the transverse direction nor the braced frames in thelongitudinal direction have the capacity to resist EQ-Il within theacceptance criteria. It is therefore recommended that seismic upgradeconcepts be developed.

Sheet 7 of 23

Figure F-3. Building with steel ductile moment-resisting frwes and teI braced frames. (Sheet 7 of 23)

F-45

TM 5-809-1O-2/NAVFAC P-355.2AFM 88-3, Chop 13, Sec B

)1.0

4

7a-

t%)

'4.1

0.8

U

.aq

00 as 1.0 1.5 2.0 2.5

e Ito O D, -r (sec))

tuFff T smctr 20 ox CAPAirY SEC.TIU& VALUSsmecr 4 Ft vaSVCMS 5crtA

CAPACITY SPECTRUM MErH OD

Sheet 8 of 23


a

F-46

TM 5-809-1O-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec B


Structural Upgrading Concepts. Three alternative concepts wereconsidered for the transverse direction. For the longitudinaldirection only one concept was-considered.

Transverse Direction:Concept 1. Modification of the existing four non moment-resistingframes to ductile moment-resisting frames to match the strengthof the existing three ductile moment-resisting frames. This wouldrequire the strengthening of the members of the frames as well asthe beam-column joint with doubler web plates and horizontalstiffener plates. This work would be difficult to accomplishespecially when the facility is in operation.Concept 2. A transverse lateral load resisting system consistingof the existing three ductile moment-resisting frames modifiedwith eccentric steel bracing. In this concept the roof metal deckhorizontal diaphragm would be overstressed for EQ-II forces andwould require strengthening by adding a concrete fill to the metaldeck. This would also require strengthening of the existing roofpurlins to support this additional load as well as removal of theexisting roofing and re-roofing. Additionally the column anchorbolts would need strengthening to resist the higher overturningforces.Concept 3. A transverse lateral load resisting system consistingof the existing three ductile moment-resisting frames and theexisting four non moment-resisting frames modified with eccentricsteel bracing.

Longitudinal Direction: For the upgrading in the longitudinaldirection, the number of braced bays are increased to meet theacceptance criteria for EQ-II forces. The modification indicatedin Design Example E-3 of the SDG (sheet 34 of 34) proposedincreasing the size and changing the configuration of the existingbraced bays. This concept resulted in unacceptable uplift loadson the columns and was discarded in favor of increasing the numberof braced bays.

Recommended Concept.

Transverse Direction. Concept 3 is the recommended transverselateral load resisting system as it is considered to be the leastexpensive to construct and causes the least interference to theoperation of the facility. Sheets 10 and 11 indicate the structuralmodifications of this concept and the basis for this designexample.

Sheet 9 of 23


F-47


rECCENTRIC BRACED(NEW)

SYM. ABT.

L .,MOMENT RESISTING FRAMES

(EXISTING)

it?) @1 1P TI 0

0f

0-::clAs ROOF PLAN

ECCENTRIC BRACED(NEW)

. Al

LrRESISTING FRAMES(EXISTING)

I

0-

0

(

, 0%Dx

3-0

x

-4Xr

NEW LONGITUDINAL BRACING

2nd FLOOR PLAN (3d FLOOR PLAN SIMILAR)

Sheet 10 of 23

J

Figure F-3. Building with steel ductile moment-resisting fRiames and steel braced frames. (Sheet 10 of 23)

F-48


SYM. AST.

I

0D 01W14x3O I

0 0 0

.f

:4

'Zi

.

.. .

x

WISXAOI1. _ _ . -

- -.. �NI8%66STif ?xY&,0 - b e 4 r ._ _ _ _ _

A ~ [ L-KI.t - ; _ - -^ I P .

( EXIST S 5x5xk BETWEEN2 & 3 AND 5 & 6.

* s =

I-EW ITS 5XSxk -JTYP. U.O.N.

LINES A &

BRACED FRAMES

NEW TS 5x5xk

NEW TS

LINES 2 3. 5. & 6 LINES 1 4 & 7

ECCENTRIC RACED FRAMES MOMENT RESISTING FRAMES

Sheet 11 of 23


F-49


Longitudinal Direction. Two additional bays of bracing (columnlines 3 to 5) on each exterior wall (column lines A and C) arerecommended for upgrading the 2nd story in the longitudinaldirection, and 4 additional bays are recommended for the 1st story.An elevation showing the new brace layout is shown on sheet 10.

Confirmation Analysis. The modal analysis to confirm compliance of themodified building was made with the aid of a general computer program forstatic and dynamic analyses of frame and shear wall three-dimensionalbuildings (TABS 4.0) for both transverse and longitudinal directions.The SRSS of the dynamic modal responses are indicated on sheets 14 and 15.

Flexibility of the Roof Diaphragm. The computer program used for thedynamic analyses assumes rigid diaphragms. This assumption isessentially valid for the existing structure except for the roofdiaphragm in the transverse analysis. The horizontal roof loaddistribution to the moment resisting and eccentric braced frames ofthe transverse dynamic analysis was reviewed based on the actualflexibility of the metal roof diaphragm and the rigidities of thelateral resisting frames using a static computer program. The resultsfrom this analysis indicate that at the roof level the exterior momentresisting frames on lines 1 and 7 resist approximately 10 percent lessload and the eccentric braced frames on lines 3 and 5 resistapproximately 5 percent more load than that from the rigid diaphragmdynamic analysis.

Torsional Forces. Due to the symmetry of the structure lateral loadresisting system there is no "calculated torsion." The "accidentaltorsion" is the story force times the nominal eccentricity of 5 percentof the maximum building dimension. The torsional forces for each storyare distributed to the lateral force resisting frames in accordancewith the method illustrated in the BDM Example A-3 and added to theforces from the dynamic analysis.

Structural Member Responses:

EQ-II Seismic Forces. Sheets 16 and 18 indicate the SRSS memberresponses from the dynamic computer analyses for EQ-II. For Frame4 (moment frame) and Frame 3 (eccentric braced frame) the responsesare given for the rigid diaphragm analysis and also the adjustmentto the response for torsion. The torsional responses were obtainedby applying a torsional moment, at each story, equal to the storymass times 5 percent of the maximum building dimension (i.e., 196feet). The effect of the flexible roof diaphragm was ignored.(Ignoring the 10 percent decrease in Frames 1 and 7 is conservative.Ignoring the 5 percent increase in the eccentric braced frames onFrames 3 and 5 may be slightly unconservative, but this effectoccurs only at the roof level and these frames have the reservecapacity for this additional load.)

Sheet 12 of 23


F-50

TM 5809-10-2INAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

Dead Load and Live Load Forces. The dead and live load memberresponses are indicated on sheets 16 and 18. Note that for theeccentric braced frames, the bracing does not participate inresistance to dead loads (assumed to be resisted by the existingframing before the braces are installed), but does participate inresisting the live loads subsequent to the installation of thebraces.

Combined Responses. Sheets 16 and 18 indicate the combined (DL +0.25LL + EQ-Il) responses for Frames 3 and 4. The results of thecalculations of the demand versus the allowable inelastic demandratio (IDR) for representative structural members are shown onsheets 17 and 19.

Roof and Floor Diaphragms. The addition of the four eccentric bracedframes in the transverse direction greatly reduced the diaphragmsshears to well within the Acceptance Criteria requirements.

Overturning Forces. A check of the overturning forces due to EQ-IIresulted in no uplift on any of the columns of the lateral load resistingframes. Soil pressures on the column footings due DL + 0.25LL EQ-IIwere less than 1.5 times the oil pressures for the dead load pluslive loads.

Sliding Resistance. Resistance to sliding forces of EQ-I aredeveloped through friction on the foundations and the passive soilpressures on the footings and the foundation grade beams perpendicularto the lateral forces.

Conclusions. The modified structure meets all the acceptance criteriarequirements for EQ-II forces. The member element stresses were wellwithin the acceptance criteria requirements. The primary reason for theplacement of the K-braces on lines A and C in every bay was to preventuplift on the columns of all the lateral load resisting frames.

Sheet 13 of 23

Figure F-3. Building with eel ductile moment-misting frames and steel braced frames. (Sheet 13 of 23)

F-51

TM 5-809-102/NAVFAC P-355.2IAFM 88-3, ChOp 13, Sec B

MATHEMATICAL MODEL - TRANSVERSE DIRECTION

R ,a- HR w 11.64 lip-Sec/Ft.

2

3 H3 21.96 ip-Sec /Ft.

2~~~~~2 2' 21.96 1:ip-Sec Ft.

T1 " 0.365 Sec., T2 u 0.174 Sec., T - 0.100 Sec.

TOTAL BUILDINGs 3 MOMENT FRAMES PLUS 4 ECCENTRIC BRACED FRAMES I

EQ II STRUCTURAL RESPONSE - TRANSVERSE DIRECTION - SRSS

LEVEL STORY LOAD** STORY SHEAR DISPLACEMENT STORY DRIFT?'""No. FX - ip V - ips - Feet 4 - Feet

3 456 456 0.125 0 22*

2 563 931 0.077 0.040

0.0381 331 1186* 0.038 0.110*

* MAXIMUM ALLOWABLE EQ 1 STORY DRIFT - 0.010H

** FxC V + W 06

C =Y. W =.663

Sheet 14 of 23

Figure F-3. Building with steel ductile moment-resisting fames and steel braced fames (Sheet 14 of 23)

F-52


MATHEMATICAL MODEL - LONGITUDINAL DIRECTION, FRAME A

R

3

2

1

MR - 5.82 ip-Sec2/Ft.

0~~~~~~~~~~~~~

H - 10.98 Xip-Sec Ft.

M2 = 10.98 ip-Sec2/Ft.0

T 0.190 Sec., T2 0.089 Sec., T = 0.058 Sec.

- FRAME A REPRESENTS OF THE BUILDING

EQ II - STRUCTURAL RESPONSE, LONG. DIRECTION, FRAME A - SRSS

LEVEL STORY LOAD** STORY SHEAR DISPLACEMENT STORY DRIFT**¢No. F - ips V - ips t- Feet Ax - Feet

3 -223 223 0.033 0.110*

0.102

2 264 469 0.021 0.11*

1 163 588 0.010 0.010_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _0 .1 1 0 *

* MAXIMUM ALLOWABLE EQ II STORY DRIFT O.O1OH

-** Fx £(Fxm)3 h

&x ' = 0.653

CB= YB - = 0. 657

Sheet 15 of 23

Figure F-3. Building with steel ductile moment-resisting frames and steel braced franes (Sheet 15 of 23)

F-53


ACCIDENTAC TORSION FORCES

Since the roof diaphragm is relatively flexible, the accidentaltorsional forces are applied only to the 2nd & 3rd floor levels.Due to the symmetry there is no "calculated"torsion. The accidentaltorsion is the story shear, V times the nominal eccentricity of5% of the maximum building dimension.

Mt = Vx x 0.05 x 196' = 9.8 Vx

The story relative rigidity (K) of each frame line is obtained fromthe computer analysis.

Direct Shear 5 K VX

Torsional Shear = d x 9.8 Vx

3rd Floor Level

FRAME REL DIRECT TORSIONALLINE X d Kd Kd2 SHEAR SHEAR

1 1.0

2 4.75

3 4.75

4 1.0

5 4.75

6 4.75

7 1.01 22.00

96

64

32

0

32

64

96

96

304

152

0

152

3n4

96

9216

19456

4864.

0

4864

19456

9,216

0.045VT

0. 21 6V

0. 21 6'1tr

O.046VT

0.216VT

0.216VT

0.04 5VT

O.009VT

0. 0 2 7 7T

0 .014VT

OVT

0.014VT

0.029VT

0.009V)

A 36.43 2A

C 36.43 24

2nd Floor Level

FRAME RELLINE K t

1 1.00 94

2 2.61 64

3 2.61 3;

4 1.00 I

5 2.61 3;

6 2.61 61

7 1.00 94

I 13.44

A 26.66 2

C 26.66 24

4

4

874 20,984 O.SOVL

874 . 20,984 0.50VLt 109,016

I

2

2

4

S

Id

96

167

84

0

84

167

96

xd2

9,216

10,691

2,673

0

2,673

10,691

9,216

DIRECTSHEAR

0.074VT

O.194VT

0.194VT

0.074VT

0.194VT

0.194VT

0.074VT

O.5VL

0.5OVL

O.0 7 9 VL

0.0 7 9VL

TORSIONALSHEAR

0. 0 1 2VT

O.022VT

0.CI1VT

OVT

0 .OIIVT

0.022VT

O.012VT

0.08 3 VL

0.08 3 VL

!4 640 15,356

4 640 15,35675, 872

Sheet 16 of 23

Figure F-3. Building with steel ductile moment-resisting fames and steel braced frames. (Sheet 16 of 23)

F-54


EQ-II ELEMENT FORCES TRANSVERSE (N-S) DIRECTION - FRAME 4

DL & LL RESULTS FROM DESIGN MANUAL ECAMPLE A-3, SHEET 18 QF 34.SEISmIC RESULTS FROM COMPUTER ANALYSIS.ALL END MOMENTS AND SHEARS GIVEN AT FACE OF SUPPORT.UNITS ARE ., -Ft.

A. b = SW b. x 0 :. =: W :

30 39 22 27a

In

%0

%0

%0

'-4.

V4C%

,. N

C4

DEAD LOAD

38 ;3

36 55° .

cn 0

LIVE LOAD

91 89

209 242-

UN - oN

* 235 276 _

an A - l.O4 0 0%

TOTAL - .OD + .25L + .OE

H

ii

H

: VW :> :K = >

55 53 M. no,

in%0

%0

1% 0

120

0%

115 4

0 .e-4

156 146 I

co%0

oi 0co

0V4

H C.

%0

p14

p4

el.

%0oW

H

HNCnp4

'U'N4

0 0%'U'

0%'-4

SEISMIC - EQ-II, SRSS

Sheet 17 of 23


F-S5

TM 5-809-10-2INAVFAC P-355.VAFM 88-3, Chap 13, Sc B

EQ II ELEMENT STRESSES - FRAME 4 (DMRSF)

BEAM ELEMENTS a EQ-IIF7 - 36 ks

UC 1.OD + 0.25L + 1.0E

MD mec MD IDR**

EVEt SIZE (In 3 ) (K-Ft.) (K-Ft.) H11 .

ROOF Wl4x30 47.3 91 142 0.64 2.0

3 W18x55 112 242 336 0.72 2.0

2 WlSX6O 123 276 369 0.75 2.0

*USEM * C 1 R

**INELASTIC DEMAND RATIO

COLUMN ELEMENTS s EQ-II UC 1.QD + 0.25L + 1.OEF - 36 ksi

y

I 'II I I I I IFIGURE 4-2, M IH c y (yu * IDR)

x cpx

Sheet 18 of 23

Figure F-3. Building with steel ductile moment-resisting frames and steel braced frames. (Sheet 18 of23)

F-56


EQ-II ELEMENT FORCES t TRANSVERSE (N-S) DIRECTION - FRAME 3

DL LL RESULTS BASED ON SIMPLE SUPPORTED ROOF & FLOOR GIRDERS.SEISMIC RESULTS FROM COMPUTER ANALYSIS.ALI: END MOMENTS AND SHEARS AT FACE OF SUPPORT.UNITS ARE r, -Ft.

0 0 H 0 20 0 M

CI4 0

'-I

0

0v.4 0%T

0

00 0

t0

0

H 0 0

o1 0_ _

c

0

Net

0r< °

H 0

0

o00 o

0

60.-

H

H

DEAD LOAD trI LOAD

z IL >I

4 109 8 4 114 8

6 265 12 \

1 27 6 toGs.

%0

to

W.

%o

K D .

r4.

H

H

wi,n14r

el.--s')11

M V%eqS

SEISMIC - EQ-II, SRSS TOTAL u 1.OD + .25L + .OE

(INCLUDES ACCIDENTAL TORSION)

Sheet 19 of 23


F-57


EQ II ELEMENT STRESSES - FRAME 3 (ECCENTRIC BRACED FRAME)

BEAM ELEMENTS : EQ-II UC l.OD + 0.25L + .OEF = 36 ksiy

A Zx PD MD Py Mpcx MD *

SIZE (in2) (in3) (kips) (K-Ft.) (kips) (K-Ft.) pCX IDR

W14x30 8.83 47.3 47 114 318 142 0.80 1.5

W18x55 16.2 112 111 265 583 321 0.83 1.5

W18x6O 17.7 123 123 287 637 351 0.82 1.5

pcx

COLUMN ELEMENTS : EQ-II UC I l.OD + 0.25L + l.OEF = 36 ksiy

A Zx Fb MD H px HD

SIZE (in2) (in3) (kips) K-Pt.)I (K-in) (kips) (kips) (K-in) (K-in) p I

W4x43 12.6 69.7 147 3 36 453.6 352.0 2509 2020 0.02 1.25

114x61 17.9 102 133 30 360 644.4 548.0 3672 3459 0.10 1.25

mr < Y~x P u @- =DR)

K-BRACE ELEMENTS : EQ-II UC ' l.OD + 0.25L + I.OEF = 36 ksi

y

A r kl/r Fa PCr _1.7 FaA -D E

LEVEL SIZE (in2) (in) (ksi) (kips) (ki s) ) cr ___

3 - R 'IS cxi 4.54 1.91 133 10.28 65 55 0.85 1.0

1 - 2 T 6x6&e 7.95 2.25 225 12.98 154 151 0.98 1.0

)

Sheet 20 of 23

Figure F-3. Building with steel ductile moment-resisting firames and steel braced frames. (Sheet 20 of 23)

F-58


EQ II ELEMENT FORCES t LONGITUDINAL E-W) DIRECTION - FRAME A

DL & LL RESULTS BASED ON SIMPLE SUPPORTED ROOF & FLOOR GIRDERS.SEISMIC RESULTS FROM COMPUTER ANALYSIS.UNITS ARE K, K-Ft.

iz

'-4

.4

0VA

0

P.

W0

-4

+O

0

O

r4

19

.4

o

c.n

i_

0

4

C4

0

I-A

3L)

.4x

z'

047

Ad

L * .Z 6 0 0 0

Sheet 21 of 23


F-59


EQ II ELEMENT STRESSES - FRAME A (BRACED FRAME)

K-BRACES, 2nd STORY (GOVERNS) EQ II UC 1.OD + 0.25L + 1.OEF = 36 ksiy

A r kl/r* F P = 1.7F Ap P DSTEEL I a Cr a D D I (in 2 ) (in) (ksi) (kips) (kips) P IDR

Sx~e-, 14.54 1.91 1105.4 12.28 94.8 89 0.94 1.0

* k = 1.0 L19.42' - (1.50 x 19.42 / 11l 12"/' = 201.3"

COLUMNS, St EQ II UC 1.OD + .25L + .OEF = 36 ksiy

COL PD MD P P M M MDy cr PC PC IDRSIZE (kips) (kips-in) (kips) (kips) (kips-in) (kips-in) M

W14x43 179 - 453.6 366.3 - - 0.49* 1.00

W14x4b §5 483 507.6 412.3 2822 2707 O.18- 1.50 ,,)D/ cr

-: SEE FIGURE 4-2

BEAM ELEMENTS EQ IIF = 36 ksi

MD/M u (u = IDR)

UC 1.OD + 0.25L + .OE

BEAM PD : - Pcr MPX M pcx MD* ISIZEy rJ C-ID

(kips (kips-in) (kips) (kips) (kips-in) (kips-in) pcx

ROOF 40 228 318.6 252.0 1703 1757 0.13 1.50

FLOOR 132 660 425 405.2 2822 2445 0.27 1.50W18x4

*SEE FIGURE 4-2 MD/Mpcx u Cu = IDR)

Sheet 22 of 23


F-60


6x6

711 .I

.(, %-1. � I1 , L. . .. . . . . .

SEQ a-aLEG OF L

SECTION a-a

NEW BRACING DETAIL

Sheet 23 of 23


F-61

TM 5-809-10-2/NAVFAC P-355.2IAFM 88-3, Chop 13, Sec B

DESIGN EXhMPLA F-4

TEN-STORY CONCRETE FRAME AND SHEAR WALL BUILDING

Purpose. This example is presented to illustrate a procedure to evaluatean existing reinforced concrete structure, determine if it satisfies theacceptance criteria, and develop an upgrading concept for resistance toseismic forces.

Description of Structure. A 10-story office building (plus basement)with lateral force resisting systems consisting of reinforced concretemoment-resisting frames in the longitudinal direction and reinforcedconcrete shear walls in the transverse direction. The building wasdesigned and built in the late 1960's in accordance with the provisionsof the 1964 Uniform Building Code (UBC). The earthquake design provisionsare essentially identical to "Seismic Design for Building" (DM) dated15 March 1966 (TM 5-809-I0/NAVDOCKS P-355/AFM 88-3, Chapter 13). Thesedesign provisions had not yet provided for concrete ductile moment-resisting space frames. However, the designer had provided some of theductility requirements later adopted by the UBC and included in the April1973 edition of the BDM. The ductility was provided using the conceptsdeveloped by Blume, Newmark, and Corning in "Design of MultistoryReinforced Concrete Buildings for Earthquake Motions," Portland CementAssociation, Skokie, Illinois, 1961. The structural design concepts areillustrated on sheets 2 through 5.


Roof:Built-up roofing.Reinforced lightweight concrete slabs, joists, and girders.Suspended ceiling.

Typical Floors:Reinforced lightweight concrete slabs, joists, and girders.Asphalt tile.Suspended ceiling.

Basement Floor:Reinforced concrete slab-on-grade.Asphalt tile.Suspended ceiling.

Foundation:Reinforced concrete mat.

Columns:Reinforced lightweight concrete.

Exterior Walls:Reinforced concrete.

Sheet 1 of 32

Figure F-4. Building with concrete moment-resisting frames and shear walls. (Sheet I of 32)

F-62


Q 0 0D82'-O"

4 , O. 1, 25*-99" 30'-6"0- 25'-9"9t-'40-9

I * -r

I

Ij II I ).18"x 72, TYP.I

IE --- 1i

124x 36, lYl~ I

.11, 'I

Z10'x 23½"T~lI l

*1 'I

I ' I'SI

D

0-7 _

IA

"-4

it

0

.I

N o0e !O, 0W -

A.

-- I0

18"x 48", TYP.I (18"x 60, .2nd Flr)N'

2-26"x 24" WITH A36" HAUNCH, TYP. I

t=-- =====-

CONCRETE JOISTS, TYP.

I , I ; )

Ii =0= _@ === =--S

I II -

-0

-0

-0-

-0

%OIs~l

'' FN D. MAT to

_ ~NTYPICAL FLOOR FRAMING PLAN

EXISTING STRUCTURE Sheet 2 of 32

Figure F-4. Building with concrete moment-resisting frames and shear walls. (Sheet 2 of 32)

F-63


Q 0 082'-Off

- 25'-9"I 30'-6" L 25'-9"

onnr±zuur

10th _ _

9th _ _ ___ _ ._-_ ;__ _ ;_ ,_._._ :.

8th

7th - _ 9

0 -r

6th 12". REINF CONC .. WALL,. TYP;S

5th ! = ~

4th e

3rd _ =

2nd _, ~r ,r_ -

)lb

1st '

Base- I IMeat r>-

'-~. 2

'9

= - .. *

III'''''�..III'.I

17 " W

- WING WALL

_ . . _ . .

U

I- 90 -O"1FOUNDATION MAT-

LINES l & 8 (EXISTING)

Sheet 3 of 32


F-64


A 0820' -Of_

0251-9'- 1 S0--6- _; 25--9-

ROOF I n

10 th _, _. 1_____ 1

th 0 T J ii I

7th g _ .. _ __ _ __ _ _______

5th i IT i6th i ii ii 1*

tb~H~I

4 th __L iF. 11. ..

aUt [I I04 C 1.9 1~~~~~~~~- ...... . 6-! ~I

Basq-ment

6%. a 4 or

II4,

W.. N.. L ....

. l . , &7 WING WALL

-- I :.; . V-� 4-- '1 I .4'3. :. .*.. ,.:

, -

X _ . ....

Au!

I. 90.1 0 _o .I I,.

FOUNDATION AT

FRAME LINES 2, 3 4, 5, 6 & 7(EXISTING)

Sheet 4 of 32


F-65

91 -

l

Isco

0

%0

z

n

*19

4A

,

co

a

CA)L A0to

cn

rt

Ln

0

MiK)

0

TYPICAL LONGITUDINAL SECTION TYPICAL EXTERIOR ELEVATION

(


Original Design. The original design for earthquake forces was based onthe 1964 UBC (similar to 1966 BDM). The base shear was determined asfollows:

V = ZKCW

where Z = 1.0 (seismic zone coefficient)K - 1.0 (building systems coefficient)C = 0.05/T1 / 3

In the transverse direction, T 0.05 h/D1/2 0.68 secC 0.057

In the longitudinal direction, T 0.1 N 1.0 secC 0.05

The weight W - 32,600k on the basis of regular weight concrete. Reinforcedconcrete design criteria were based on working stress design (WSD).

Design base shear:

Transverse - lxlxO.057x32,600 = 1860kLongitudinal = lxlxO.05x32,600 - 1630k

Note: Due to "fast-tracking" of this building, the foundations weredesigned and under construction prior to completion ofsuperstructure design. Because the above building weight wouldhave overloaded the foundation soils, it was decided to uselightweight concrete for the frames and floors but not for theshear walls. This reduced the weight to 27,040k and increased theeffective base shear coefficients to:

V/W 0.069 transverseV/W 0.060 longitudinal

In addition to the minimum requirements of the code, the engineer decidedto supply additional detailing to provide ductility in accordance withthe concepts developed by Blume, Newmark, and Corning. This includedadditional column ties (or hoops) in the column and in the beam-columnjoint zone to provide for confinement.

Sheet 6 of 32


F-67


Site Response Spectra. Site response spectra, which are used for thepreliminary evaluation, the detailed analysis, and the upgrade concept,were developed in accordance with the procedure in chapter 3 of the SDG:

Building Classification: Others

Ground Motion Spectra: ATC 3-06 Map Contour LevelAa = Av - 0.30

Soil Classification: Si 1.0 (Type S)

Earthquake IDamping - 5X, D.F. 1.00 (SDG table 3-7)Aa Av - 0.14g (Design Ground Motion, SDG table 3-4)Sa =D.F. (1.22AvSi)/T - 0.171g/T less than D.F. (2.5)Aa 0.35g max

Earthquake IIDamping 102, D.F. 0.80Aa Av 035gSa =D.F. (1.22AVSi)/T - 0.342g/T less than D.F. (2.5)Aa 0.70g max

EQ-II/EQ-I 0.70/0.35 2.0


Sheet 7 of 32

Figure Fa. Building with concrete moment-resisting frames and shear walls. (Sheet 7 of 32)

F-68

I TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

DESIGN RESPONSE SPECTR4 FOR EQ-I AND EQ-II

sate

o.0 '0.0 1.0 2.0 3.0

PERIOD, SECONDS

4.0

EQ-JB - - 0 .4881-- .80 PERIOD

EQ B 0.0 .488 .80 1.0 1-.5 | 2.0 ' 3.0 4.0

I 5%Sa'g .14 .35 .214 .171 114 .085 .057 .043

II 1 Sg .35 .70 .427 .342 .228 .171 .114 .086a

Sdtin 0 1.63 2.68 3.35 5.02 6.70 10.04 13.47

SPECTRAL DISPLACEMENT S d= Sa(T/2w) 2g

Sheet 8 of 32


F-69


Preliminary Evaluation. A rapid evaluation of the structure was made )using available data. For the longitudinal direction, the capacity wasapproximated by using the design base shear and assuming yield was at twotimes design. For the transverse direction, the capacity was approximatedfrom the strength and area of the shear walls. Calculations are shownon sheets 10 and 11. The capacity spectrum method (sheet 12) was usedto approximate damage. Over 100 percent for transverse, 70 percent forlongitudinal, and 99 percent for combined (total) damage due to EQ-II.The results of the preliminary evaluation indicate that the structurewill be substantially damaged by EQ-Il; however, for a smaller earthquake(e.g., EQ-I) the results of the evaluation indicate that the structurewould remain essentially elastic. Because of the size and value of thebuilding, it was decided that a detailed analysis would be warranted tomore accurately determine how the structure would perform under EQ-I1loading.

Sheet 9 of 32


F-70


RAPID EVALUATION PROCEDURE

Longitudinal Direction: Moment frame

Effective design base shear coefficient at WSDV/W 0.067

Yield Capacity

Assume yield at 2 x designCB 2 x 0.067 = 0.134

Estimate period: T = 0.1N - 1.0 sec

EstimateC CB/Sa = 0.80 (SDG para 5-3a(2

Sa CB/0.80 0.168g

Sd Sa x g x (2 1.64 inches

Estimate roof displacement,ARR P.F.ROOF x Sd t- 1.3Sd = 2.1 inch

Average interstory drift ratioA R/H 2.1/124 x 12 = 0.0014

Ultimate Capacity

Assume: ULTIMATE CAPACITY - 1.5 x YIELDULTIMATE DISPLACEMENT = 4 x YIELD

)(c))

es

SaU

SdU

TU

- 1.5 x 0.168g 0.252g

4 x 2.1 inches 8.4 inches

2- TFd/Sa - 1.84 sec

Sheet 10 of 32


F-71


RAPID EVALUATION PROCEDURE (continued) ,

Transverse Direction: Shear Walls

Effective design base shear at WSD: V - 1860k; V/W U 0.076Area Shear Walls: (82' x 1')2 x 144 - 23,616 square inchesWall Capacity: 12" wall w/#4 at 12"ef,ew

2 f - 2 3000 - 110 psi*

pfY 2x0.20 x 40,000 - 111 psilf 2x12

Total 221 psi

VCAPACITY 0.221 x 23,616 - 5220k

*May be 5000 psi concrete, see etailed analysis

Yield Capacity

CB Vp/W - 5220/24500 0.213

Est. Roof Displ.: Shear A AG S150 psi (avg) x 124x12- b 0.2"AG1501.2XI06 -

Bending: PL3 , 2/3(5220)x1243x12 - 0.66"3EI 3(3xlo3zl44)x46000x2

A Ret 0.9"+

If T 0.68 sec (sheet 6) and Sa = B. 0.27g:

Sd (2) Sa x g - 1.22"; AR t 1 3Sd -5"

Assume A R - 1.0" (includes rocking added to 0.9")Sd - 1.0 . 1.3 - 0.77" and Sa 0.27gT 2Sd/Saxg - 0.62 sec

Ultimate Capacity

Assume SaU - 1.25 x 0.27 - 0.34gSdU - 4 x 0.77 - 3"T - 0.95 sec

Sheet 11 of 32

Figure F-4. Building with concrete moment-resisting frames and shear walk (Sheet 11 of 30)

N~)

)

F-72

. TM 5-809-10-2/NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

\ EQ-II, - 5%

!I r-EQ-lI,I i.

- 102

-Damage - 114X (transverse direction)1o

I,

So

a0

-4

Ij.

63

0 0.5 1.0 1.5 2.0 2.5

Period, T(sec)

Rapid Evaluation

Transverse direction:

Longitudindal direction:

Total damage:

114% damage

70Z damage

2/3(114) + 13(70) - 99%

Sheet 12 of 32


F-73


Acceptance Criteria (para 5-2). The acceptance criteria for existingbuildings are those presented for the post yield analysis for EQ-II inthe SDG with latitude allowed under certain conditions.

Conforming/Nonconforming Systems and Materials. The reinforcedconcrete moment frames do not strictly conform to current standards;however, some ductility provisions were incorporated into the designand the current condition of the building is good. Therefore, thestructure will be considered essentially conforming with some latitudeallowed in the acceptance criteria.

Method 1. Elastic Analysis Procedure (Refer to SDG paras 4-4c and5-5a).

Classification:

Loading Combination:

Other Buildings

DL + 0.25LL + 1.0 EQ

Ultimate Strength Capacities: ACI 318 Strength Design

Inelastic Demand Ratios: (tableReinf. Conc. Frames

ColumnsBeams

Reinf. Conc. Shear WallsSingle Curtain Reinf.Double Curtain Reinf.

Reinf. Conc. Diaphragms

Material PropertiesLightweight ConcreteRegular Weight ConcreteReinforcement

Story Drift Limitation:

5-1)Nonduct.1.251.75

Ductile1.753.00

Avg.1.52.4

Shear-1.50, Flexure-2.0Shear-1.75, Flexure-3.0Shear-1.75, Flexure-2.0

fc 3750 psifc 4000 psiFY - 40 ksi

0.015 x Story Height

)

Method 2. Capacity Spectrum Method (Refer to SDG paras 4-4d and 5-5b).If the acceptance criteria of Method 1 are not satisfied, the structurewill be analyzed in accordance with Method 2 prior to developing aseismic upgrading concept.

Sheet 13 of 32

)


F-74


Detailed Structural Analysis.

Method 1. The existing structure was analyzed with the aid of acomputer. Gross concrete section properties of the girders and columnswere used for the moment frame. For simplicity the haunches wereneglected. Also, the stiffening effects of the floor system wereignored in the mathematical model. It is assumed that the contributionof these items to stiffness are relatively small and are balanced outby neglecting the reduced stiffness effects of nominal "cracked"section properties.

The mathematical model was subjected to an elastic modal analysis usingthe design response spectrum for EQ-I, 10 percent damped, shown onsheet 8. The results of the analysis gave the following:

Fundamental Period (sec)Base Shear, 1st Mode (kips)Base Shear, RSS (3 modes)Roof Displacement (ft)Roof Acceleration, 1st modeRoof Acceleration, RSS (3 modes)

Transverse0.4613,98014,4850.1721. 00g1.10g

Longitudinal0. 809,5209,7640.2920.556g0.656g

The results indicate that the structure is relatively stiff, such thatthe calculated periods are shorter than the empirical periods used inthe original design (sheet 6). The EQ-II shear forces are 7.5 timesdesign in the transverse direction and 5.8 times in the longitudinaldirection.

Sample IDR*'s of the most critical elements follow:Calculated

Transverse Shear Walls IDR 2.94Longitudinal frame, girder bending IDR - 2.3Longitudinal frame, column bending IDR = 2.0

*IDR's are calculated by dividing the computer calculatedstrength capacity for each element.

Allowable1.75 N.G.2.4 O.K.1.5 N.G.force by the

The conclusions of the Method 1 detailed evaluation indicate that theexisting building does not conform to the acceptance criteria.However, the results are based on a gross concrete section model. Withlarge overstresses it is likely that the period will lengthen (due tocracked concrete) and reduce the effective earthquake forces on thebuilding. It should also be noted that as some elements yield,additional load will be distributed to other members. In the elasticmodel, the transverse interior frames only take about 3 percent of thelateral forces. However, if the shear walls yield, the frames can

Sheet 14 of 32


F-75

TM S-809-10-2/NAVFAC P-355.2/AFM 88-3, Chop 13, Sec B

contribute some backup resistance. In order to get a better feel forthe inelastic response of the building a Method 2 analysis was done.

Method 2. The Capacity Spectrum Method uses a step-by-step, pseudo-inelastic approach to approximate the inelastic capacity of thestructure. This capacity is compared by means of a graphical procedureto the demands of the EQ-I response spectrum. Guidelines for thisprocedure are presented in the SDG, para 5-5.

For this example, the pseudo-inelastic analysis consisted ofconsecutive elastic analyses of an initial mathematical model of thestructure that was modified in an iterative fashion to include theresults of the previous analyses and loaded incrementally. The processbegan by defining the initial 2-D model as is typically done for anycomputerized elastic analysis (e.g., the analysis used in Method 1,sheet 14). In addition, beam yield strengths for positive and negativebending, beam shear capacities, and beam and column gravity inducedforces were computed. For beams to be subjected to negative seismicbending, a seismic reserve capacity equal to beam negative yieldstrength less gravity moment at the face of support was computed. Forbeams to be subjected to positive seismic bending, the seismic reservecapacity equals the beam positive yield strength plus the gravitymoment at the face of support. For columns, P-M interaction diagramswere used to aid in identifying load capacities as shown on sheet 17.

The incremental loading regimen commenced with the application of theEQ-II Spectrum (sheet 8) loading to the 2-D mathematical model of theinitial structure. Seismic member forces derived from this analysiswere compared to member seismic reserve capacities to identify thefirst set of plastic hinges to form and to obtain the maximum memberoverstress factor. The initial loading, SaII, divided by thisoverstress factor defines the load, Say, at first yielding as well asthe seismic member forces associated with first yielding.

For the second step, the mathematical model was altered to includepinned member ends which reflected the first set of plastic hingelocations. This model was subjected to a small, monotonic, incrementalload, Sai, and reanalyzed using the same elastic computer program.The new set of seismic member forces obtained from this was added tothose corresponding to first yielding and this sum was again comparedto the member seismic reserve capacities; thus a second set of plastichinges could be identified. Subsequent analyses were performedidentically, each time including the new set of plastic hinges in theprevious model and comparing the summation of the member forces ofprevious analyses to the initial member seismic reserve capacities.The method of superposition of the incremental loads are illustratedin sheets 19 and 20 of Figure E-3 of the SDG.

Sheet 15 of 32

wBw r t f d l)

Figure F-1. Building with concrete moment-resisting frames and shear wails. (Sheet 15 of 32)

F-76


Longitudinal Direction. The results for the longitudinal directionare shown on sheets 18, 19, and 20. Sheet 18 shows the sequenceof plastic hinges. Sheet 19 shows the relationship between V,&R9CB, S, Sd, and T and plots the capacity curves. Sheet 20 showsthe graphical solution for the capacity spectrum method.

From sheet 20 it appears that the structure, in the long direction,can survive EQ-Il without collapse and that it will remainessentially elastic for EQ-I. The capacity curve crosses thedemand curve (EQ-I) at approximately S - 0.244g and T - 1.44 sec.

Sd (T/21y)2SSg - 4.95"

AR 1 .3 0Sd - 6.42"A R/H - 6/124 x 12 - 0.0043, Avg. drift ratioIf worst story - 2 x Avg

Max. story drift ratio - 0.008 < 0.015 O.K.

Although these analytical results are encouraging, the "survival"of the building against collapse for EQ-I should be consideredmarginal. More conservatism in modeling, application of the modalstory force, or consideration of possible beam/columndeterioration due to repetitive cycling of the inelastic rotationwould tend to depress the capacity curve of sheet 20 below thedemand spectrum of EQ-II.

Transverse Direction. The detailed evaluation for the transversedirection was not in the scope of this example. Because thecalculated period of the structure is shorter than the one obtainedby the empirical formula, it appears that the performance of thestructure will be worse than approximated in the rapid evaluation.However, it should be noted that a detailed evaluation of the shearwall energy absorbing capabilities after initial yielding may showthat the performance characteristics of the transverse directionare better than anticipated.

Results of Detailed Structural Analysis. Although the results indicatethat the building may be severely damaged if subjected to the EQ-IIearthquake, the overall performance characteristics are relatively goodconsidering the age (pre-1973) and type of construction (reinforcedconcrete frame). It appears that the building will perform in anessentially elastic manner for EQ-I but compliance with the acceptancecriteria for EQ-Il may be marginal. It is therefore recommended thatupgrade concepts be developed and that a cost-benefit study be made todetermine priorities for upgrading.

Sheet 16 of 32


F-77

TM 5-809-1-2NAVFAC P-355.2AFM 88-3, Chop 13, Sac B

P(Kips)

Column interaction curve, from ACI SP-17A

(use - 1.0 if as-builtcondition is known)

- flP

I L ..-.--- Capacity of olumn

)DL a

H (K-Ft)

0 9 % L- DL+LL

Sheet 17 of 32

Figure F-4. Building with concrete moment-resisting frames and shear walls (Sheet 17 of 32)

F-78


FRAMES & C

Roo

lOt

9tl

8d

h-

t k4 6 A 6 6 6 7

-4. A 4A 60

2 83 8 3 83 13 a 3 S.- 34 se ._ 3 3 -8 3 -3I 2 -8 3 I 8 3 1 8 3 1 8 3. -8 3-1 5

7t]

6tI

5tl

4th- - *

3rd- 2 8 3 8 L 3 3_ 3 S 3d_- Z- _*M _

2 44 .4 6

lat...

Loadl 1cod ! 1 1 2 3 4 5 6 7

S^ !.144g .038 I .0lZ l0g, Olt6 *01g .g .01g .0ig8a II

* Load increment

FRAMIES A DRoof-

10th- 8 8 8 8 8 8 8

7 8' 5 6 5 6 5 6 S 6 5 6 7 8eth e * * @ * * * ** *-4-|

7th t34 3 i34

6t- 23 3 I gA'

5tL 3 3 2 2 22 2 2 22 2 2_

4tb_ 2 2 1 2 1 2 1 2 , 2 1 2 2

3rd 2 2 1 2 1 2 1 2 1 2 1 2 2 2

2 4 4 3 3 3 3 3 3 3 3 3 3 4 4

Is 7 7 t17 7 7

Sheet 18 of 32


F-79

TM 5-809-1O-2NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

EQ-II: CAPACITY SPECTRUM ( - 2 7, 0 0 0K)

iCk . S *f1 1S Sdi Id R Zi V C T CD - - = = -~~~~~~~~~~~~I Z d Ls

1 0.144g 0.94" 1.250.144S 0.94" 1.2S 3256 0.120 0.817 1.33 0.83.

2 0.03 0.24 0.310.174 1.18 1.56 3931 0.147 0.832 1.32 0.84

3 0.01 0.14 0.170.184 1.32 1.73 4154 0.153 0.856 1.31 0.83

4 0.01 0.27 0.320.194 1.59 2.05 4379 0.162 0.915 -1.29 0.84

5 0.01 0.41 0.500.204 2.00 2.S5 4606 0.170 1.001 1.28 0.83

6 0.01 0.48 0.600.214 2.48 3.15 4830 0.179 1.088 1.27 0.84

7 0.01 0.54 0.690.224 3.02 3.84 5051 0.187 1.174 1.27 0.83

8 0.01 0.92 1.230.234 3.94 5.07 5285 0.196 1.312 1.29 0.84

9 0.01 1.01 1.850.244 4.95 6.42 5517 0.204 1.440 1.30 0.84

)6000

5000

- 40004: 3000

> 2000

1000

)~~~ ~ ,9I I m st yield

Exis8ting design

1 2 3 4 5 6 7

0.20

to

CS

2

1.0 2.0.

T(sec)

Sheet 19 of 32

Figure F-4. Building with concrete nonent-resisting frames and shear walls (Sheet 19 of 32)

F-80

TM 5-809-10-2/NAVFAC P-3SS.2/AFM 88-3, Chop 13, Sec B

0.7

0.6

0.5

0.4

Sa(g)

0.3

0.2

0.1

0 O

response to EQ-II:- 0.244g

- 1.44 sec

0.5 1.0 1.5 2.0 2.5

T(sec)

Sheet 20 of 32

Figure F-4. Building with concrete moment-resiating frames and Ahear walls. (Sheet 20 of 32)

F-81



Structural Upgrading Concept. The recommended upgrading conceptsinclude the addition of interior cast-in-place reinforced concretewalls, to resist the transverse seismic forces and reduce the diaphragmstresses, and the placement of cast-in-place reinforced concrete panelsin alternate window openings in the exterior concrete frames to resistthe seismic forces in the longitudinal direction. For plans andelevations of the upgrade concept see sheets 22, 23, and 24.

Confirmation Analyses. A modal analysis of the modified structure wasmade with the aid of a general computer program for the static anddynamic analyses of frame and shear wall three-dimensional buildingsfor both the transverse and longitudinal directions. The programassumes rigid diaphragms and the roof and the floor diaphragms of thismodified structure essentially meet the requirements of thisassumption. The mathematical model as assumed fixed at the firstfloor level. The dynamic modal responses are indicated on sheets 25and 26.

Structural Member Responses. Sheets 27 and 28 indicate the SRSS ofmodal responses for representative structural members in the transverseand longitudinal directions. The accidental torsion responses werecalculated as described for design example F-2 and are given on sheet29. A check of selected structural elements for compliance with theacceptance criteria is given on sheets 30 and 31.

Torsional Forces. Due to the symmetry of the structure lateral loadresisting system there is no "calculated torsion." The "accidentaltorsion" is the story shear times the nominal eccentricity of 5 percentof the maximum building dimension. The torsional forces for the roofand the floors are distributed to the lateral force resisting elementsin accordance with the method illustrated in the BDM Example-A-3 andadded to the forces from the dynamic analysis.

Overturning Forces. A check of the overturning forces due to EQ-IIresulted in no instability of the structure as a whole. The soilpressure at the toe of the foundation mat due to DL + 0.25 LL + EQ-Itforces in the transverse direction exceeds more than twice of theallowable design soil pressure when based on a. triangular distributionof the soil pressure. Soil pressure under a rectangular distributionassumption results in a soil pressure less than twice the allowabledesign pressure. A Soil Engineering firm should be consulted to re-evaluate the allowable soil pressure and the shape of the soildistribution pressure under dynamic loadings.

Sheet 21 of 32


F-82


I -%- FND. MAT

TYPICAL FLOOR FRAMING PLAN

Sheet 22 of 32


F-83


Q 0 82'-0"

25'-9. . 30-6" 25*-9"c-. _ -

ROOF. I iI-

th10 -- o' - - -. -. X . . .

T j - . . .

th9.

th 08

Cth f-

7 II

6th 0..6 a

5 th e,V-.

th '4r o

3rd '%

.. . .

I, ~~. *. _ _ _ _

.10"'. REIN.. .. N.

CONC::.IN-F rANE"O..'f ';. .... ...~

,)'.*. . .. . .. . . .. I 4'_-�- ... "

2nd =l _ _ _ *. .I .. . I .. .~~~~~~~

0.

St . 1 ,-~

.'r *. .:- .

'' :- ' .'I . . .A -., -, .-�. :..,.

1 53' 8 '.''* I� ___

Base-ment \

z. j '7 :. . '.I-:, . . -I ,. .

I ., I , -. .- WING WALL

0-

U,

*.I 1. D6 . I- 0, 0 ... - . †. . ...

90.-o.

FOUNDATION MAT

. SHEAR WALL LINES 4 & .5.(NEW).

Sheet 23 of 32


F-84

C (

5 SPACES 27 -O" = 135'-O" 0 27 -6127'-6'

ROOF

10th

4 1.- 1. I

9th

8th 0r4

n7th

0

6th N

5th U'114

4th Un04

3rd

-iEIrEm

~~~~I

~~~~I

Em

ILIIIEmElEmEmEm

I

LJ

LI

r-L 'C.I,;.L~Iz

E:mEZl

I Em--I

LIZI~ ~ ~~l LIII77-Em~~~~~~~~ Em. -- .LIII Eli-7-1

Em~~~~L Em' '-

Em Em~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Em~~~~~.-1 Em-=

I . , .EM-7 -IEm ~. -:.

I

LIIj

IIIII I

' 2nd p

1st -I

o A1Bkse- Iment) !

I

III

9

-Ico00

a0

1z

,n

InU'

*I

0

Cdala

(4

0

e L:-; -' I

DrN 10" REINFI CONC. IN4ILL PANELS

4 I 4 I A 80

wN

I I

i ' - ,1 I,, ... - I .-

uI

2'--o'ilIfAfff v

190'-O" )2 '-0I I - _______I I 4�-FOUNDATION MAT

FRAMES LINE A & D

u'

TM S-809-10-2NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

EQ II STRUCTURAL RESPONSE - SRSS

90.02 3033 0.202 0.014

86.87 2576 0.1885594 0.017

86.87 2284 O. m7783 0.020

89.06 2136 0.1529704 0.022

91.25 1995 0.13011,394 0.024

91.25 1786 0.10612,509 0.025

91.25 1577 0.08213,945 0.024

91.25 1399 0.057

91.25 1122 14;810 0.035 O.02215,406 0.019

101.48 751 0.016 016910.55 15,760**> 0.°160*

I IIXMATHEMATICAL MODEL

T - 0.511 Sec.

T2 a 0.144 Seo.

T3u s0.073 Seo.

;* MAXIMUM ALLOWABLE STORY DRIFT . OOH

**t Fx - Et FxmlP ̂ v; = [tVxm2i P

.Ax MITxn-x gh jA = i-xm21.j

fia* C. b +1'LW 0.537

LONGITUDINAL DIRECTION

U - 910.55 x 32.2 - 29,320 kijs

NOTEs ZFx Vx UE TO HIGHER MODE PARTICIPATION EFFECTS ON FORCES.

I X =A x BECAUSE .IGHER MODE PARTICIPATION EFFECTS ONDISPLACEMENT. ARE NEGLIGIBLE FOR THIS BUITDING.(i.e. RSS DISPLACEMENTS ARE ESSENTIALLY

EQUAL TO st MODE DISPLACEMENT.)

Sheet 25 of 32


F-86


EQ II STRUCTURAL RESPONSE - SRSS

Ham R im I& SR S LPM

(!LP-Seq. /Et. I Fks) m ((KipSec.Ft. (Idps) | (kps) (Feet) (Feet)

R

10

9

- .7 U

6 y

4

3ac

2

5,s

-7

90.02

86.70

86.70

89.06

91.25

91.2S

91.25

91.25

91.25

101.4891W,55

3286

265S

2649

2058

1909

1731

1571

1413

1163

82

3286

5917

9815

.,363

12,662

13,724

14,565

15,182

15,586 **

.0.105

0.093

0.081

0.069

0.057

0.046

0.035

0.025

0.016

0.008

0.010.120*

0.012

0.013

0.011

0.011

0.011

0.010

0.009

0.008

0.0080.160l0

MATHEMATICAL MCT, - 0.352 Sec

T2 0.103 Sec

T3 - 0.054 Sec

NOTES Fx

'ISx CA

tDEL

* MAXIMUM ALLOWABLE STORY DRIFT = 0.0 1H

**. FX - EI(Fxj); 3 VX = [V.l 3

Aax ca( xm) A 6/=[.jxm2]k

£Ai* Cb Vb +%-W 0.537

TRANSVERSE DIRECTION

W u 910.55 x 32.2 29,320 kips

!x DUE TO HIGHER MODE PARTICIPATION EFFECTS ON FORCES.

BECAUSE IGHERm oDE PARTICIPATION EFFECTS oNDISPLACEMENT ARE NEGLIGIBLE FOR THIS BUILDING.(i.e. RSS DISPLACEMENT ARE ESSENTIALLY EQUAL

TO 1st MODE DISPLACEMENT.)

Sheet 26 of 32


F-87


EQ II ELEMENT FORCES: TRANSVERSE DIRECTION - WALLS 4 & 5

SEISMIC RESULTS FROM COMPUTER ANALYSIS.UNITS ARE KIPS AND KIP-FT.

SHEAR MOMENT

Roof

10th

9th

8th

7th

6th

5th

4th

3rd

2nd

1st

329

690

1130

2778

2969

3132

3260

3335

3361

3269

3943

12224

25759

58983

94367

131525

169990

209139

248405

299234

9_11

Sheet 27 of 32

Figure F-4. Building with concrete moment-resisting frames and shear walls. (Sheet 27 of 32)l

F-88


EO II ELEMENT FORCES: LONGITUDINAL DIRECTION - FRAME LINES A & D

SEISMIC RESULTS FROM COMPUTER ANALYSIS.UNITS ARE KIPS AND IP-FT.

= > z > = >

Roof 5419 S615 117 677 M

10th

9th

8th

I4

IAI

;I

7th

1I4

' 525 1190 - -4 0 f4 N 0

Iva 1769 1798 866 806r~~~n- - '.0 170 80

I-' N 0 s 0 oN N .-4

_______________ _____________ a2115 2137 1063 968o W N 203 97.

0' 0 t -)0 '0 -ts-4 N 10 N r7

2420 2439 1275 1173A C4 47 en co ON O 231 1i7

C4-t 1 r -4 Cj n O 4

__________ _ '2650 2668 1447 1337W 40 an c 0' eq 253 133In q co e)n o o% o r0 LA _ -a co - en 0

2775 2791 1595 1490%0r%- Oe^ N 265 143

o -a . f D en. M O tor4 o0 .-4 0

Ln '.0:0 _ - .-' 2757 2772 1595 1490

'. 263 147fn -a N e 0 LAv

co 000 4o NNs e4 _4 Nn C1

N r4 2557 2570 1519 1431

244 140fl- r^ r s O Oo0tJ b-4 ,,a-N4 0 '

-4 -4 NR NI

co , _ < 42128 2139 1325 1287< ffi N e 203 124

o n 4r4 a,.rI '- 0 N1

Nv -. tz ̂ N s ^- (96)o _____________% ' 2619 2635 1528 1346

6th

V

HV

HV

HV

HV

HV

HV

HV

HV

HV

5th I

4th I

3rd.

2nd

1stNNo0

N%

N 0N co

0'

i -in 17

'0

0'PN

0'0 0

an

N

250(16)

136

SYM. ABT.

(DL + LL)

Sheet 28 of 32


TM 5-809-1O-2NAVFAC P-355.2/AFM 88-3, Chap 13, Sec B


The "accidental" torsion is the story shear, V, times the nominaleccentricity of 5 of the building dimension.

Mt = Vx x 0.05 x 190' = 9.5 Vx

The story relative rigidity (K) of each shear element is obtainedfrom the computer analysis.

Torsional Shear = - x 9.5 VX-

* r-~~~Kd2

Direct Shear = x VX

Distribution of Forces

9th Floor Level

SHEAR RELELEMENT K

1 19.99

2 0.35

3 0.35

4 8.15

5 8.15

6 0.35

7 0.35

8 19.99,-= 57.68

A 16.77

B 1.00

C 1.00

D 16.77= 35.54

d Kd Kd2

94.5 1899 178516

67.5 24 1595

40.5 14 574

13.5 110 1485

13.5 110 1485

40.5 14 574

67.5 24 1595

94.5 1889 178516

DIRECTSHEAR

0.3 4 7VT

0.006 VT

O.006 VT

O. 141VT

0. 141VT

O.006 VT

O. 00 6 VT

°. 3 4 7 VT

O.472VL

O.0 2 8 VL

O . 02 8 VL

O.4 7 2VL

TORSIONALSHEAR

0.043VT

O.OO1VT

°.OOOVT

O.002VT

°.OO2VT

0.OO1VT

O.0 4 3 VT

O.015VL

°0.000VL

0.OOOVL

0.015VL

)

40.25

15.25

15.25

40.25

675 27168

15 233

15 233

675 27168Z= 419142

Sheet 29 of 32

Figure F-4. Building with concrete momnt-resisting frames and shear wls. (Sheet 29 of 32)

F-90



2nd Floor Level

SHEAR RELELEMENT K

1 29.66

2 0.27

3 0.27

4 21.90

5 21.90

6 0.27

7 0.27

8 29.66z= 104.20

A 24.84

B 1.00

C 1.00

D 24.84X- 51.68

d Kd Kd2 DIRECTSHEAR

94.5 2803 264871 0.285VT

67.5 18 1230 0.003VT

40.5 11 443 0.003VT

13.5 296 3991 0.210VT

13.5 296 3991 0.210VT

40.5 11 443 0.003VT

67.5 18 1230 0.003VT

94.5 2803 264871 0.2 85VT

TORSIONALSHEAR

O.0 4 3 VT

O.OOOVT

O.OOOVT

O.OOSVT

O.005VT

O.OOOVT

O .OOOVT

0 .0 4 3VT

0 .O15VL

O .OOOVL

0 .OOOVL

O.OlSVL

40.25

15.25

15.25

40.25

1000

15

15

1000Z.

40242

233

233

O.481VL

°.OO9VL

° . OO9 VL

O. 4 81VL40242- 22020

Sheet 30 of 32


F-91

TM S-809-10-2NAVFAC P-355.2AFM 88-3, Chap 13, Sec B


Wall Lines 4 & 5

Neglect accidental torsional forces; less than 5% of thetranslational forces.

K�A

FLOOR VD Vu Y2 SHEAR MD MuLEVEL kips kips Vu IDR ft-kips ft-kips

MD MOMENTmu IDR

8th 1130 1050 1.08 1.75

ISt 3269 2710 1.20 1.75 2

25729 15350 1.68 3.00

299234 107080 2.79 3.00

Frame Lines A & D

Neglect accidental torsional forces; less than 5% of thetranslational forces.

At ISt Floor Level

MEMBER VD Vu Vn SHEAR MD MuELEMENT kips kips V,, IDR ft-kips ft-kips

MI MOMENT_Mu. IDR

Wall 2447 14?0 1.72 1.75

Beam 266 281 0.95 1.75

90148 37740 2.39 3.00

2731 1712 1.60 1.75 ,)

Sheet 31 of 32

Figure F-4. Building with concrete moment-resisting frames and shear walls (Sheet 31 of 32)

CONCLUSIONS

The structure, as modified by the upgrading concept, will conform to theacceptance criteria for EQ-I1 forces; however a verification of soilcapacities will be required as stated on sheet 21. It should also benoted that the detailed analysis of the existing structure (withoutmodifications) indicates that the building has good overall performancecharacteristics, vill remain essentially elastic for EQ-I, and wouldsatisfy acceptance criteria for an earthquake slightly smaller thanEQ-II (refer to sheet 16). Because this building is not an essential orhigh risk facility, the need for upgrading would be set at a relativelylow priority as a result of formulating a decision by means of acost-benefit analysis.

Sheet 32 of 32

Figure F4. Building with concrete moment-resisting frames and shear walls (Sheet 32 of 32)

F-92

TM 5-809-10-2/NAVFAC P-35S.2/AFM 88-3, Chap 13, Sec B

APPENDIX G

DESIGN EXAMPLES-NONSTRUCTURAL

G-1. IntroductionThe design examples in this appendix are toillustrate principles, factors, and concepts de-scribed in this manual for the anchorage or brac-ing of nonstructural elements in buildings.

G-2. Design examplesThe following design examples are representativeof typical nonstructural elements supported on theroof or on a floor of any building. The variousexamples illustrate the procedures for evaluationand upgrading rigid and flexibly mounted equip-ment and nonstructural partitions and light fix-tures. Following is a listing of the designexamples.

Fig. No. Description of Design ExamplesG-1 Nonstructural partition: illustrates

seismic evaluation and method ofbracing partitions.

G-2 Unit heater-supported from struc-tural framing: evaluates existingflexible support and upgrades sup-port by providing rigid brace.

G-3 Light fixture: illustrates evaluationand upgrading procedure for exist-ing light fixtures.

G-4 Tank system bolted to floor of build-ing. Evaluates anchorage to floorsystem and provides bracing sys-

G-5tem.

Piping system: Provides seismic brac-ing for existing piping system.


GIVEN: NONSTRUCTU2AL CONCeETE LOC.KPAQT(TIONS /N A IO-STORY REINFOfCeCEDCONCRETE FRAME 8UILIDING. REFE 70LONGITUDINAL DiRECTION IN FIG. F-4 FOR.BUiLDING PROPERTIES. PARTITIONJS ARENOT IN CONTACT WITH ANY S2UCTUZALELEMENTS OTHER THAN FLOOR SLAB.THEY EXTEND 4" ABOVE -FOOT CEIL/GAND THE TOP OF TU4E BLOCK9 Ai2EROUGCHLY /'-8" 5ORT OF THE SOFFIT OFTHE FLOOR ABOVE. THE WALLS AZE a,8NOMINAL TICKNESS WITH NOMINALREINFORCING (E.G., 44 AT 4-I'O CTRS EACHWAY)

ESTIMATE PEQI2OO

# = f =,ZG )~{7$- 15.3 Ho

r E = X/Orm psiX~ =~ 5 ,,,~4 (I- FT S rI P)W = 5o"0// 4� ' //rnL =6 ~- 4' I0O -S/7= W/38G = 0. 010 1 )

IT = OoG6 Sec (CANTILEVEe WALL)

THIS 15 P-ELATIVELY RIGID COMARED 7nBLllN01MG PERIOD: T 0.80 SEC

Tz = . 26 ECT3 = 0.14 SEC

THERE FORE, ASSUUME RIGID AND USEPEAK FLOOR ACCELERATIONFOR PRELMINARY CHIECI/,

PEAK BLDG RESPOnSE:

rLONG 0rREC770AI NtCONCRETE FRAME/

RSS AT 9TH FLOOR

MOVET

Gaa*,

/ 2a 0o o 2G0432 0.70a.54 0.25

30.140.700-08 -(frmFL

9E42 = 0.609 (ACCELERATION)

Sheet I of 3

I

Figure G-1. Nonstructural partition. (Sheet I of 3)

G-2


CHECK CANT1LEVEk WALL

FOR R/GID WALL CEC*( I0 0.6O 9

WL 2.. 7 _ =

o.GO. o(s3= 4O t 'I9a

(4' WI0TH & o,GO 8)

ESTIMATE TENSION ' #4 £E-O-a4k

f- 7% 7- =-a ::: 41GOAl =T3 /I, 200 a 3.5G

'.� 4 �-

FLOOR AR- /14 .2 =(Kc

A Q20L1" 7 sc"

&BACE PARTITION* I. 1-

( BA

t4) BAJZ

ES7/MATZE /NTeR sT0RY DISPLACMENrS

WOST CASE: 897TWEE 2D 4 3RD FLOORS AY 1AISPECrlON)kOWC LDG C4LCSJ

M0Dw

A 3

A 3 -A 2

I2.72"If

1.330.840.49

MAX/MUM

20.45"0.200.150.0.a

0.030. 030.00 k!5 = . 4-9

/I4T5PS7ZRY GRIFF

Sheet 2 of 3

Figure G01. Nonstructural partition. (Sheet 2 of 3)

G-3


V~~/GN BI2AC~~ BOTTOM O0F MUtSSD_G__ BRACE O SAB

TRr DE TA IL A-1 ACSHOWH N,BDM4, PfG 9-I -- 777....... _7

- rmwTH R-F~~~= CGO~~p 77CAL SLOT_, a 60 W - .- C~;cRc)A

CGJLIMVG- ...: BOLTSWp 4'X 50/o SECTION A -A

z oo *Fr7RIB. 7Z OP cA'HAb aeACf-iOF WALL . --

0,o60 X 2oo

SPACE gACES AT 8-FEET CENT;ES

8 X /20 = 9600/RACE )

k NOTE ON BOLTED COHN9CT/ON.:

VSE V/A G/EZS AS 6PACEŽS -8=7WEEA/BRACE AAID SLAD AND BETWEEN BEwACEAND SLOTTED . T//S WILL ALLOWFO z SoME /ER,0roz- aei/rPARALLEL T WALL.

Sheet 3 of 3

Fgure G-1. Nonstructural partition. (Sheet 3 of 3)

G-4


UNIT HEATEA SUPPORTEOby -V/4!'# 35-O'PIPEa,IZIGIOLY ATTAC4EO TOCEILING.

- , , . , , . \

11

1%1�111to

I

01A �-" C-S

_. TI YZ. , ,-,T

111111111111 / h/, -rGot _

GIVEN: NEGLECT EFFECTS OF I2OTATION OF UNIT/EATEU .

Wp

W

= WT. UNIT r4EATER - 360= WT. 7YPICAL FLOOg= '300= WT. STRa/CTIRwE Vb00

I C OCCUPANCY) = J. OZONE 6 SSISMIC AEATo( V4 9 PIPE ) = 0.037 N 4

E (PIPE) - 0.K/ 8K P

L&B9KIPS

V/N.

01

cl

C.G.

pxa/ooet i*ACE

.vz-e 'x x 4AL'sA = 2 . 54q) = 1a,6 Im

. 4Z - %!*PiPE5A-.53).GG IN.Z

Sheet 1 of 2

Figure G-2. Unit heater. (Sheet I of 2)

G-5

TM 5-809-10-21NAVFAC P-355.2/AFM 88-3, Chap 13, S~c B

GIVEN: UNIT HEATERS SUPPORTED BY 2- PPES\3'0"LOAG, RIGIDLY ATTACHEO TO SLAB5OFFIT.THE UNITS AE LOCATED N A 7-Sm0rBUILDING.THE EVALA17ON OF- THE RESPONSE oEQ-I AND EQ -7 AZE SHOWN /M FIGUREF-2 IN THE SG.EQ -ir FORCES EQUAL .501 LBS.

THIS l=)(CEED5 THE CAPACITY OF THE PIPESUPPORTS TO RES15T LATERAL FORCES. (SEE8DM o2EI6N. EXAMPLE F-5)

f MC 1/ X __ X 36 ) _/

I 0.CL037 /N 4 MGOPS

THEREFORE, BRACE THE SUPPORT

THE SOLUTION FOR DESIGNING THE BRACE 15SHOWN IN $DG FIG. F-3

DESIGN THE BRACE FO2 A FORCE EQUA L -215 LB5

Sheet 2 of 2

Fiure G2. Unit heater. (Shee 2 of 2)

G-6

TM 5-809-10-2INAVFAC P-355.21AFM 88-3, Chap 13, Soc B

LIGAT F/KX TR S /N EX/SJING /4/bui0NG

GIVEN '

F/,I T4R/SPbY MGALA 774 CME O

s#P~~~~~oo~~~~rf-, f , ,

RODS-i RIGII.)41TO C614 NG

.. .1 * 10,-

LEhNSS ARC GLASS

EVALUA710oNLArCRAL ORC6 iDUG 2QU IN JTWENe/G/11bO1?Rooa top 0.(Ox WF(IRFCA roZ/G G- POX ACCGLERA47IONS)/1R6S6rS$ H4AZAROS:

1. FAI4URC OP MErAL ROOSg. 1*ojT1J/A1r**TY OP G44SS fbREAI<AG6

.SOL UJVON

A4TERJNrE # /

4 LTERNA rE e

4eP44Ce WT/7ATEW o&/X'7Y// S

* R6P4ACd GLA5S MI PA src LENSCS* 6A4 SUPPLemeNr4aY CASLeS AS

ACK- UP IN CSE OA ROO PA/ILURE

Figure G-3. Light fixtures

G-7


- - - WT. ojcWANT- ?0 kJPS-.-- W7, OA P400R- 14C0 CooXI

rs -0 _- coNXvrierI. 74e1( RJGtr3L Y

. .Mout~rejra RL0 %rNA T OOl ,b 4'5.o - Z .POA C s' I=e2.3I((RfgA ro XMG PIG. F-* FOe

DeîS/M _NA rOM OP POCSS)

-2 - r r2^- -,,, vv,,^z EPECT1V4 W7OTH O f6ASw

FOAC ES ON ;UCHORAGe.S

'a MO-( X 112.3) - (-5 0

__.3 _ f -5X T= 0

T 2 .3 <IPS U,0i,.7,

R -?'V:, V2 al? K

*-OVAW l~xvzvt~ I tF Y, V 2 V6.Z -2

I U41FT OOcCUR AJUUMErOrA fW R r4iceW. far V.V

7TA N .JVWGN 4NCHOA lbOcrS

ANn XUJIQPO 7i. ?.3 icipr ra44ION' ANO

(i~e1(iJ J401AJ??. 0 t o on

J'. 3 %$HeAPR

Figure 0-4. Tank system bolted to floor of building

3j,)

G-8


mome4r C S%/ATNGeP C$ FAMS I5 '1 i.

WA7r1/ CAArANG PIP&fs.L(ATA/RA ccY 4P/'tol Z,Ar ACf P4CO10 -

Wr. ( 0 f) Pi

A T &4SE ( POINt a )

I_i .I - -I|

~. 4o

COas%a

'4-, I

_a - I. * - . L J,A. . . %

*@?00:4o.o6tM~~~~~~~~~Ol GIVeNPING 4J rWOW#V IN S %JrOaY r7664 MOM6M47

AC-.FJ6TING PACC ARAME 9PlEAK4 FLOO/k ACCeLEA4rION O.G0gPEAKC {sNMW7r0Y Ji~r I,. I N

PIPING XY4rtTM COaNI4/6RC-D AZ 1GItD(AEAC 7 PfM (3 $SVGN eXAMPLCE F ')

wr o /*P 4 COlrSATr =4 /$oS r7'

M4XIMCU CGrTat41 OJ C' AT iIPE %rUPC/oirF,:

Fa- (14#101 K &.3) O.Co 117 C.5

1NrE/ SrO~rY fD/Rl/tTJ1.2 lN4. RELAVVYE t3IALAC0MeNT IN /0 Fr. C4NEXCECD (3fO MArlo CAPACIrY O I"t PtPE ;

1. rXUAMY PLC KJfC UPPOAT A r , C ANMI OR

Z.epp cJPceftXI/bL JOINTS,

Figure G5. Piping system

G-9

TM 5-809-10-2INAVFAC P-355.2AFM 88-3, Chap 13, Soc B

BIBLIOGRAPHY

Applied Technology Council, "An Investigation of the Correlation Between Earthquake Ground Motionand Building Performance," ATC-10, Palo Alto, California, 1983.

Blume, J. A., et al., "Design of Multistory Reinforced Concrete Buildings for Earthquake Motions,"Portland Cement Association, Skokie, Illinois, 1961.

Chopra, Anil, K., "Dynamics of Structures-A Primer," Earthquake Engineering Research Institute,Berkeley, California, 1981.

Freeman, S. A., "Prediction of Response of Concrete Buildings to Severe Earthquake Motion," DouglasMcHenry International Symposium on Concrete and Concrete Structures, American Concrete Institute,SP-55, Detroit, Michigan, 1978.

Freeman, S. A., Nicoletti, J. P., and Iyrrell, J. V., "Evaluation of Existing Buildings for Seismic Risk-ACase Study of Puget Sound Naval Shipyard, Bremerton, Washington," Proceedings of the U.S. NationalConference on Earthquake Engineering-1975, Earthquake Engineering Research Institute, Berkeley,California, 1975.

Murphy, L. M., Scientific Coordinator, "San Fernando, California, Earthquake of February 9, 1971,"Effects on Building Structures, Vol. 1, U.S. Department of Commerce, National Oceanic andAtmospheric Administration, Washington, DC, 1973.

Newmark, N. M., and Hall, W. J., "Procedures and Criteria for Earthquake Resistant Design" BuildingsPractices for Disaster Mitigation, Building Sciences Series 46, National Bureau of Standards, Washing-ton, DC, 1973.

Seismology Committee, "Recommended Lateral Force Requirements and Commentary," StructuralEngineers Association of California, San Francisco, California, 1980.

URS/John A. Blume & Associates, Engineers, "Effects Prediction Guidelines for Structures Subjected toGround Motion," JAB-99-115, San Francisco, California, 1975.

Base Isolation Subcommittee of the Seismology Committee, "Tentative Seismic Isolation Design Require-ments," Structural Engineers Association of Northern California, San Francisco, California, 1986.

Scholl, R. E., "Structural Dampers: An Alternative Procedure for Retrofitting Buildings," Proceedings ofthe 3rd U.S. National Conference on Earthquake Engineering, Charleston, South Carolina, 1986.

Applied Technology Council, "Proceedings of a Seminar and Workshop on Base Isolation and EnergyDissipation," ATC-17, Palo Alto, California, 1986.

Benjamin, J. R., and Cornell, C. A., "Probability, Statistics, and Decisions for Civil Engineers," McGraw-Hill, New York, 1970.

Bibliography-l

TM 5-809-10-VNAVFAC P-355.2/AFM 88-3, Chap 13, Sec B

INDEX

ParagraphAcceptance criteria .................... 5-2, 6-2, 9-2All other buildings .................... 1-4b, 1-ScAlternatives .................... 1-4b, 5-2c, 6-3Analysis procedures .................... 5-3fAnnualized costs .................... 7-4, 7-6Approval authorities .................... 1-2Architectural elements .................... 9-3, 9-6aAvailable design data .................... 3-2bBase isolation .................... 6-3aBase shear .................... 4-2c(4Xa)Basic Design Manual (BDM) .................... 1-1Basis of Design .................... 6-6a, 8-3aBibliography .................... 1-8Capacity .................... 4-2c, 4-2d, 5-3d, 7-3aCapacity Spectrum Method .................... 4-2c, 4-2dCommunications .................... 1-5a(5), 9-6c(5)Compatibility .................... 6-3aConcepts .................... 1-7e, 6-3, 6-6Concrete ......................... 6-4b (2,3,4)Configuration .................... 6-3aConforming materials .................... 5-2aConforming systems .................... 6-2aConnections ......................... 6-4b(lXd)Contract documents .................... 1-7g, 8-3Cost benefits ................... 1-7f, Chap 7Costs .................... 4-2e, 6-3f, 7-5, 7-7Damage ................... 4-2d, 6-3e, 9-3bDamageability .................... 7-3Damping Ratio .................... 4-2d(2Xb)Deficiencies ..................... 5-3g, 6-4cDefinitions .................... 1-3Demand .................... 4-2d, 5-4dDesign data .................... 3-2bDetailed structural analysis .................... 1-7d, Chap 5Diaphragms .................... 5-3g(3Xb), 6-3a, 6-4b(7)Document review .................... 4-2a, 5-SaDrawings .................... 8-bDrift ................... 6-2a, 6-Sa(7)Dynamic analysis procedures ................... 5-3f, 9-5Earthquake risk ................... 7-2Electrical elements ................... 9-3Elevators .................... 9-6c(1)Emergency power .................... 9-6c(2)Energy dissipation ............ ; 6-3aEQ-I .1-4a 6-3eEQ-Q .1-4aEquipment .5-3g(3Xd), 9-6bEssential facilities .1-5aEvaluation .1-c, 1-7, 4-2, 5-3f, 94, 9-5Existing facilities .1-6b 1-7, 2-1Existing materials .1-6c, 1-7i, 5-2a, 5-2b, 5-3c, 6-3a(5Xd), 6-4aField survey .3-2c, 4-2bFinal design .1-7g, Chap 8, 8-2

Index-l

TM 5-809-10-2VNAVFAC P-355.21AFM 88-3, Chap 13, Sec B

Fire protection systems ......................... 9-6c(3)Foundations ........................... 53g(3Xa), 6-3a, 6-4b(8)Hazard risk levels ......................... 1-4Hazardous buildings ........................... 1-5Hazardous critical facilities .......................... 1-5dHazardous materials .......................... 1-5d, 9-6c(4)High risk facilities .......................... 1-4bInelastic demand ratio ......................... 5-3A1), 6-3a(6)Inspection survey .......................... 3-2c, 4-2bInventory ........................... 2-2Inventory reduction .......................... 1-7a, Chap 2, 2-3Lateral displacement .......................... 4-2c(4Xb)Lateral force ................................ 4-2c(1)Masonry ................................. 6-4b(3,4)Mechanical elements .......................... 9-3, 9-6bMethod 1: elastic analysis procedure .......................... 5-3fA1)Method 2: capacity spectrum method .......................... 4-2c, 5-3A2)Methodology .......................... 1-7Mission-essential .......................... 1-5a(4)Nonconforming materials .......................... 5-2bNonconforming systems .......................... 5-2bNonessential............ : ............ 1-5cNonstructural elements .......................... 1-7h, 6-5, Chap 9P-delta effects .......................... 5-3g(3Xt)Periods of vibration .......................... 4-2c(4Xc), 4-2dPlot plan .......................... 3-3ePost-yield analysis .......................... 5-2Preliminary evaluation .......................... 1-7c, Chap 4, 4-2Preliminary screening .......................... 1-7b, Chap 3, 3-2Priorities .......................... 4-2d(6), 4-3Rapid evaluation technique ....................... 4-2cRapid seismic analysis ....................... 4-1, 4-2c, 9-4eReanalysis ............................. 6-3dRecommendations ....................... 5-4Repair costs ............................ 7-3bReports ....................... 3-3, 4-4, 5-2b(1), 7-8Response spectra ....................... 4-2d, 7-2bRisk levels ....................... 1-4, 4-2d(2Xa)RSAP ........................ 4-lbScreening process ....................... 2-1, 3-2, 3-2dSeismic design criteria ....................... 1-6aSeismic Design Guidelines (SDG) ....................... 1-1, 1-6aSeismic evaluation ....................... 1-7Site visits ....................... 3-2a, 3-2c, 4-2b, 5-3b, 9-4bSpectral accelerations, S ....................... 4-2c(5), 4-2dSpectral displacements, Sd ....................... 4-2d(5), 4-2dSteel ....................... 6-4b(1)Strengthening techniques ....................... 6-3b, 6-4Structural systems ....................... 5-2a, 5-2b(1), 6-3aSymbols ...................... 1-3Testing ....................... 1-7i, 5-3cTorsion ....................... 6-3a(4)Tripartite plots ............................ 4-2dTwo-level procedure ....................... 1-6aUpgrading ........................ 1-6c, 1-7, 6-5, 7-5, 9-6Useful life ....................... 7-4bWood ........................ 6-4b(5)

Index-2

The proponent agency of this publication is the Office of the Chief of Engineers, United StatesArmy. Users are invited to send comments and suggested improvements on DA Form 2028(Recommended Changes to Publications and Blank Forms) direct to HQDA (DAEN-ECE-D),WASH DC 20314-1000

By Order of the Secretaries of the Army, the Air Force, and the Navy:CARL E. VUONO

General, United States ArmyOfficial: Chief of Staff

R. L. DILWORTHBrigadier General, United States Army

The Adjutant General

E. R. WILSONCAPT., CEC, U.S. NAVYFOR THE COMMANDERNAVAL FACILITIES ENGINEERING COMMAND

LARRY D. WELCH, General, USAFOfficial: Chief of Staff

WILLIAM 0. NATIONS, Colonel, USAFDirector of Information Management

and Administration

Distribution:Army: To be distributed in accordance with DA Form 12-34B, requirements for nonequipment

technical manuals.Air Force: FNavy

*U.S.CDVERNME#T PRINTINdG OrriCE1988-217-404