High Performance Blast and Seismic. Handout

7/28/2019 High Performance Blast and Seismic. Handout

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Building Survivability:

Designing for Seismic &

Blast ResistanceJason Lien, P.E., FPCI

Building Survivability:

Designing for Seismic &

Blast ResistanceJason Lien, P.E., FPCI

Discuss seismic and blast design methodologiesusing precast concrete

Explain how precast concrete can be used to meetperformance needs in seismic regions

Discuss the United Facilities Criteria (UFC) anddesign methodology

Explain how precast concrete can be used to meetperformance needs related to ATFP

Learning Objectives

High Performance Precast

Precast concrete is a high performance materialthat integrates easily with other systems andinherently provides the versatility, efficiency, andresiliency needed to meet the multi-hazardrequirements and long-term demands of highperformance structures.


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High Performance Precast

Precast concrete is a high performance material thatintegrates easily with other systems and inherentlyprovides the versatility, efficiency, and resiliencyneeded to meet the multi-hazard requirements

and long-term demands of high performancestructures.

Att ributes and Benefi ts of A Total Precast System

VERSATILE EFFICIENT RESILIENT

Aesthet ic Versat ilit y Site Eff icienc y Structure Durability

Virtually any color, form, and texture Minimal site disturbance Long service life

Facade integration Negligible waste Barrier wall system

Historic compatibility Accelerated construction Functional resilience

Structural VersatilityEnergy and Operational

EfficiencyMulti-Hazard Prot ection

Long open spans Scalable performance Earthquake resistance

Economical sections Thermally efficient Storm resistance

Load-Bearing envelopes Low life-cycle costs Blast resistance

Use Versatility Risk Reduction Life Safety and Health

Adaptive reuse Design assist Indoorenvironmental quality

Deconstructive reuse Reduced detailing and trades Passive fire resistance

Recyclable Enhanced profitability Meets FEMA 361

Att ributes and Benefi ts of A Total Precast System

VERSATILE EFFICIENT RESILIENT

Aesthet ic Versat ilit y Site Eff icienc y Structure Durability

Virtually any color, form, and texture Minimal site disturbance Long service life

Facade integration Negligible waste Barrier wall system

Historic compatibility Accelerated construction Functional resilience

Structural Versatility Energy and OperationalEfficiency

Multi-Hazard Prot ection

Long open spans Scalable performance Earthquake resistance

Economical sections Thermally efficient Storm resistance

Load-Bearing envelopes Low life-cycle costs Blast resistance

Use Versatility Risk Reduction Life Safety and Health

Adaptive reuse Design assist Indoorenvironmental quality

Deconstructive reuse Reduced detailing and trades Passive fire resistance

Recyclable Enhanced profitability Meets FEMA 361


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Blast Resistance Blast Loading Member Analysis Material Response

Limits Cladding Example

Seismic Resistance Seismic Force Resistant Systems (SFRS) Emulation Examples Advances in SFRS

Designing for B last & Seismic Resistance

Blast Resistance

Sample of Governing Documents

UFC 4-010-01 DoD Minimum Antiterrorism Standards for Buildings

UFC 4-010-02 DoD Minimum Standoff Distances for Buildings (FOUO)

UFC 4-020-01 DoD Security Engineering Facilities Planning Manual

UFC 4-020-02FA Security Engineering: Concept Design (FOUO)

UFC 4-020-03FA Security Engineering: Final Design (FOUO)

UFC 4-020-04FA Electronic Security Systems: Security Engineering

UFC 4-021-01 Design and O&M: Mass Notification Systems

UFC 4-022-01 Security Engineering: Entry Control Facilities/Access ControlPoints

UFC 4-023-03 Design of Buildings to Resist Progressive Collapse

FOUO - For Official Use Only


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Sample of Governing Documents

UFC 4-010-01 DoD Minimum Antiterrorism Standards for Buildings

UFC 4-010-02 DoD Minimum Standoff Distances for Buildings (FOUO)

UFC 4-020-01 DoD Security Engineering Facilities Planning Manual

UFC 4-020-02FA Security Engineering: Concept Design (FOUO)

UFC 4-020-03FA Security Engineering: Final Design (FOUO)

UFC 4-020-04FA Electronic Security Systems: Security Engineering

UFC 4-021-01 Design and O&M: Mass Notification Systems

UFC 4-022-01 Security Engineering: Entry Control Facilities/Access ControlPoints

UFC 4-023-03 Design of Buildings to Resist Progressive Collapse

FOUO - For Official Use Only

Calculate blast loads on the component Determine the dynamic response of the component Check the response against specified performance

criteria

Design the component connections Check that the component has adequate shear

capacity.

Design / Analysis Process

Solid explosivesDust or flammable vapor cloudsPressure vessel burstsANFO (AmoniumNitrate and Fuel Oil)The fertilizer plant that blew up outside of

Waco is an example of manufacturingfacility accidents

Main Sources of B last Loading


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Detonation If the reaction speed is equal

to, or greater than, the speedof sound in the explosivematerial

High explosives, such asTrinitrotoluene (TNT) and C4achieve detonation

Considered a Shock Wave

Deflagration If the reaction moves through

the explosive material at lessthan the speed of sound inthe explosive material

Industrial explosions fromvapor and dust clouds, whichare caused by accidentalconditions

Considered a Pressure Wave

Conservative assumption to assume shockwave detonations

Pressure Time History

Pr

Based on Hemispherical shaped TNT Charge

Blast Load Pressure


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Blast Loads are assumed to be reflective Angle of incidence Assume to be 0o

Clearing discontinuities and building edges Typically ignored Reflective Pressure, P r Surface in direct path of

Blast

Side On Pressure, Pso Other surfaces Roof, Sidewalls.

Blast Load Parameters

Cube Root Scaling TechniqueCharge Weight, WStandoff Distances, RScaled Standoff Distance, Z

Various charts available Positive Phase,Negative Phase

Additional Scaling factors for other materials

Blast Load Pressure

Charge Weight, W, 100 lbs Standoff Distances, R, 50 ft

Scaled Standoff Distance, Z

10.7

Example

Open Ai r Detonations


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Cost vs. Standoff Distance

Equivalent Triangular Duration, td

Idealization o f Pressure Time History

Impulse (psi-ms)

Peak P ressure (psi)

0 td

Member Analysis


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Precast Products can be idealized as equivalentsingle degree of freedom (SDOF) systems

SDOF mass-spring systemThe blast load is calculated at midspanof acomponent and assumed to be uniform over thewhole span

Most precast members are simply supported and donot create tension or compression membranebehavior

Analysis Assumptions

SDOF

SDOF Equation of Motion

'' '

Mass of system

Damping factor assumed = 0

Resistance of system

Applied load as function of time

'' , '' , '' Accleration, Velocity, Displacement

lm c c c c

c

c

c

c

K M u t C u t R u t F t

M

C

R

F t

u t u t u t


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Factors based on flexural behavior of system under appliedloads. They vary as the member changes from elastic, elasto-plastic, plastic response. Solutions are based on energymethods

Elastic Plastic

SDOF Load, Mass Factors

Load mass factor =

Mass transformation factor

Load transformation factor

mlm

l

m

l

KK

K

K

K

Resistance Function

Simply Suppor ted Member

Elastic Mechanism

Plastic Mechanism(without strain hardening)


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Dynamic Response of Materials

' '

Dynamic Increase Factor

= 1.9 for flexural components

= 1.2 for axial components

Static Increase Factor (est. actual concrete strength)

= 1.1 conservatively take

dc e c

e

f DIF K f

DIF

K

n as 1.0

Higher Strengths under rapid strain rates

Dynamic Response of Materials

' '

Dynamic Increase Factor

Static Increase Factor (est. actual yield strength)

dy y

e

f DIF f

DIF

K

Flexural SRF typically taken as 1.0Shear SRF typically taken as 1.0

Based on conservative method of analysisand design

Strength Reduction Factors


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Dynamic Moment Capacity per uni t width

Mildly Reinforced Section

1.7 's dy s dydu

dc

A f A fM d

b bf

Dynamic Moment Capacity per uni t width

Prestressed Reinforced section

2 2

0.85 '

Based on strain compatibility

= Based on emperical methods

ps ps s dy

du ps

ps ps s dy

dc

ps

A f A fa aM d d

b b

A f A fa d

bf

f

Section Properties

Average Moment of Iner ia

2

Gross moment of inertia

Cracked Transformed Moment of Inertia

g ct

a

g

ct

I I

I

I

I


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Graphical Approach Specific FEA SolutionsTime Step Numerical Approach

Commonly used tool SBEDS

Methodology Manual for the Single-Degree-of-FreedomBlastEffects Design Spreadsheets

U.S. Army Corps of Engineers Protective Design Center Technical Report PDC-TR

06-01, Rev 1

Limited Release

Solution Methods to Solve SDOF

Protective Design Center Technical Report PDC-TR06-08, R1 1-7-2008

Support Rotation Angle, Ductility Ratio,

Limit Requirements

Based on Plastic Deflected Shape

Limit Requirement Calculations

Support Rotation Ang le / Ductili ty Ratio

1 maxtan

Span Ratio

= 0.5 for beams supported at ends

= 1.0 for cantilevers

s

s

y

C L

C

max

Initial yield deflection

e

e

y

y

y


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Protective Design Center Technical Report PDC-TR 06-08, R1 1-7-2008

Limit Requirements

Cladding Example Floor Plan

Annex

Link

Main Office

Example Design Parameters


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Example Sample Elevation

Architectural ElevationBuildingSection

Example Design Model

GradeLevel

Beam Members Column Members

MidLevel

RoofLevel

ExampleParameters

Beam Length

5' 0"9' 0" 11.5 '

2L

14 ' 6"7.25'

2B

Tributary Height

Example Equivalent Sections


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Example SBEDS

Example SBEDS

Example Panel Design Summary

2 2(4) #5 4 0.31 1.24in in


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Example Connection Summary

ConnectionElevation Connection

Forces

Compression:

Sum of BeamEnd Rxns andColumn End

Rxns

Rebound: Compression

Force

Connections

LRFD

ultimate static connection strength

from LRFD including resistance factor

Dynamic Connection Factor

= 1.0 Welded Connection

= 1.05 Bolted Connection

d u

u

F F c

F

c

Sample Mid-Height Connections

Shear Connection Compression / ReboundConnection


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Seismic Resistance

Seismic Load Path

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Primary Differences in Lateral Systems

Response Modification FactorsOver Strength FactorsDeflection Amplification FactorBuilding Height LimitationsStructural Detailing Requirements

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Lateral System Parameter Variations

R-Values - Response Modification Values

Accounts for differences in the inelastic deformability orenergy dissipation capacity of various structural systems

o- Over Strength Factor

Intended to maintain elastic behavior of certaincomponents of a system while allowing othercomponents to behave in an inelastic fashion

Cd - Deflection Amplification Factor

Modification of buildings elastic displacement to accountfor a materials inelastic behavior

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ASCE 7

Seismic Design Using Precast

Concrete Systems

Current code provisions for Precast Seismic Force Resisting

Systems (SFRSs)

ACI 318-11 introduces few changes to the provisions from the 08edition

Shear-wall and moment-frame SFRSs have 3 levels of detailingrequirements:

Ordinary, Intermediate, and Special

Ordinary, strong, or ductile discrete connections are allowed for all,except for special precast shear walls, for which CIP emulation ofreinforcement continuity is required

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Connections

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Shear Wall Connections

Intermediate PC StructuralWalls ACI 21.4

Special PC S tructural WallsACI 21.10

Forces ContinuousReinforcement through 21.9

and as such connections arebasically mechanical bar

couplers

ACI 318 21.4

Yielding must be in steel elements or reinforcement Non-ductile components and welds must be designed

for 1.5 times the connection strength

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Examples of Intermediate Shear Walls


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Intent of ACI 318 21.10

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ACI 439.3-07 Types ofMechanical Splices forReinforcing Bars

Provides information about types of

proprietary bar to bar mechanical

splices.

Availability, applications and

suitability of type 1 and type 2

splices


CIP Emulation

The philosophy of ACI 318 is that continuousreinforcement somehow has inherent ductilitygreater than any discrete connections

ACI offers documents for guidance on emulationThe only alternative to emulations is the general

provision of ACI 318, Section 21.1.1.8:

A Reinforced concrete structural system not satisfying therequirements of this chapter shall be permitted if it isdemonstrated by experimental evidencewill have strength

and toughness comparable to a monolithic reinforcedstructure.

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Examples of Emulative Design


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Trough forContinuous

diaphragm steel

Female end ofgrouted connection

Male end ofgrouted connection


Site ConditionAs Detailed


Braced Columns

Wet Joint Detail

Finished Wall


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Concrete Systems

Developments Beyond the Building Code

Precast Seismic Structural Systems (PRESSS)

Precast post-tensioned (Hybrid) moment frames Precast post-tensioned shear walls

These systems provide performance beyond Life Safetydue to their self-centering abilities (no permanent tilt after anearthquake) and limiting structural damage to a number ofdedicated energy-dissipating fuse elements. Those arepartially unbondedrebarscrossing the beam/columninterface that also provide damping for the structural system.

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Seismic Design Using Precast Concrete

Systems

PRESSS resulted in developing three documents:

ACI T1 ACI 374.1-05 Acceptance Criteriafor Moment Frames Based on Structural Testing

ACI T1.2-03 Special Moment FramesComposed of Discretely J ointed Precastand Post-Tensioned Concrete Members

ACI ATG-5.1-07 Acceptance Criteria forSpecial UnbondedPost-Tensioned P recast

Structural Walls Based on Validation Testing

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Examples of Non-Emulative Design

Moment framejoint reinforcement

Hybridmoment frame


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Non-Emulative Design Permitted

ACI 318 21.10.3

U-shaped flexural plates(UFP)

Un-bonded post-tensionedprecast wall system

Must Follow

ACI ATG-5.1


Concrete Systems

Developments Beyond the Building Code

Precast hybrid moment frames provide superior collapse-resistance performance in addition to their seismicperformance

The unbondedPT tendons provide inherent catenaryaction in cases of accidental removal of a building column

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Diaphragms

Significant component in the Seismic ForceResisting System (SFRS)

Floor PlateRoof

Two diaphragm construction methodsField Topped - Cast in place systemsPretopped systems

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Diaphragms

Pretopped Field Topped

Diaphragm Considerations

Seismic Design Category A, B, and CField topped systemsPretopped systems

Seismic Design Category D and higherField topped cast in place systemsImplicitly no recognition for pretopped

systems

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Cord Steel

J oint Shear

Connection

SFRSConnection

Pretopped Diaphragm Connections

Subject to Over Strength Factor,


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Diaphragm Connections

Connection SpacingPretoppedsystems: 4 ftto 6 ftOCField topped systems 8 ft OC

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Field Topped Diaphragms

Topping thickness 3 minimum (SDC A, B) 4 recommended (SDC C) 4 minimum (SDC D)

Recommended 4500 to 5000 psi 28-Daystrength

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Shear strength must be based entirely onreinforcement crossing the joint

The factor for the shear design of thediaphragm must be no greater than that usedin the shear design of the supporting verticalcomponents (columns or walls)

This will sometimes result in =0.6 if the factor for the shear design of shear walls isgoverned by Section 9.3.4 of ACI 318-08

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Wire Mesh size and spacing is critical, 10Spacing minimum

Preferred to have transverse steel as high inthe topping as possible

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Summary

Precast can be used for Blast Resistance andcould possibly reduce standoff distances

Multiple precast systems are available forseismic force resistance system constructionfor all seismic design categories

Thank you!

J ason P. Lien, PE, [email protected]