Consulting Engineers State of the Art Technologies State of the Art Technologies Base Isolation and Energy Base Isolation and Energy Dissipators Dissipators Protection of Nonstructural Elements and Protection of Nonstructural Elements and Contents Contents by by SEAONC Protective Systems Committee SEAONC Protective Systems Committee
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ConsultingEngineers
State of the Art Technologies State of the Art Technologies
Base Isolation and Energy Base Isolation and Energy DissipatorsDissipators
Protection of Nonstructural Elements and Protection of Nonstructural Elements and Contents Contents
byby
SEAONC Protective Systems CommitteeSEAONC Protective Systems Committee
ConsultingEngineersOutlineOutline
•• Introduction and Overview Introduction and Overview –– Ron Mayes Ron Mayes •• Base IsolationBase Isolation
New Construction – Pat Ryan Retrofit – Simin Naaseh & Mason WaltersDesign & Analysis – Troy MorganUS Code Improvements – Rene VignosSimplified Design Procedure – Gordon WrayTesting – Ian AikenProgress in Japan – N. Kani
•• DampersDampersDevices – Ian AikenAnalysis Issues – Martin ButtonDesign Issues – Mark Sinclair
•• Comparison of Systems Comparison of Systems –– Ron Mayes Ron Mayes
ConsultingEngineers
“These Recommendations primarily are intended to safeguard against major failures and loss of life, NOT to limit damage, maintain functions, or provide for easy repairs.”
Quote from the Uniform Building Quote from the Uniform Building CodeCode
Acceleration Related DamageOlive Hospital 1971 (San Fernando Valley)
ConsultingEngineers
Acceleration Related DamageTV Studio
ConsultingEngineers
Acceleration Related DamageManufacturing Plant
ConsultingEngineersIn Summary...In Summary...
•• Earthquakes are Earthquakes are inevitableinevitable
•• Ground Forces are Ground Forces are amplified by a factor amplified by a factor of 3 to 4 at the roof.of 3 to 4 at the roof.
•• Consequences can Consequences can be expensive be expensive
Conventional Structure
ConsultingEngineers
Design Codes Focus on Limiting Design Codes Focus on Limiting DriftsDrifts
•• Design codes limit drifts Design codes limit drifts –– 2 to 3 inches per 2 to 3 inches per story story
•• Drift limits are intended to protect structural Drift limits are intended to protect structural frames and some nonframes and some non--structural elementsstructural elements
•• Seismic Design Codes have never required Seismic Design Codes have never required the SE to explicitly look at the SE to explicitly look at floor floor accelerationsaccelerations. .
ConsultingEngineers
The Result of the Code The Result of the Code FocusFocuson Drifton Drift
While Ignoring AccelerationWhile Ignoring Acceleration
•• 9 Hospitals partially or fully 9 Hospitals partially or fully evacuatedevacuated
•• USC University Hospital in USC University Hospital in downtown LA downtown LA –– 1st isolated 1st isolated hospital no damage at allhospital no damage at all
•• Los Angeles County Hospital Los Angeles County Hospital less than 1 mile from the less than 1 mile from the USC isolated hospital had USC isolated hospital had $389 million in damage$389 million in damage
ConsultingEngineers
Significant $$$ Damage in Recent Significant $$$ Damage in Recent EarthquakesEarthquakes
•• Economic impact of the 1994 Northridge ($30B) and Economic impact of the 1994 Northridge ($30B) and 1995 Kobe ($200B) earthquakes caused a rethinking of 1995 Kobe ($200B) earthquakes caused a rethinking of the code design philosophy by SEthe code design philosophy by SE’’s.s.
•• Much of the downtime and damage costs was a result of Much of the downtime and damage costs was a result of nonstructural damage nonstructural damage
•• Future Codes Future Codes –– Performance Based Design Performance Based Design
The Future The Future -- Performance Based Performance Based DesignDesign
•• ATC 58 ATC 58 –– Earthquake performance will be Earthquake performance will be expressed in Deaths, Dollars and Downtime expressed in Deaths, Dollars and Downtime ––language the owner understandslanguage the owner understands
•• PBD has two very different objectivesPBD has two very different objectivesTo minimize first costs if only life safety is desired
To minimize downtime and the cost of damage if higher performance is desired
•• Designs will focus on minimizing both interDesigns will focus on minimizing both inter--story story drift and drift and floor accelerationsfloor accelerations for higher for higher performance performance
•• Current US codes provide equations for Current US codes provide equations for limits on the forces and displacements. limits on the forces and displacements.
•• SEAONCSEAONC’’ss Protective Systems CommitteeProtective Systems Committee’’s s proposal for a simplified or preliminary proposal for a simplified or preliminary design procedure will quantify the design design procedure will quantify the design forces and displacements considering all of forces and displacements considering all of the code requirements the code requirements –– property variations, property variations, torsion etc. torsion etc.
ConsultingEngineers
Cover Rubber
Energy Dissipation Core
Steel Reinforcing Plates
Internal Rubber Layers
Bottom Mounting Plate
(Top Mounting Plate Not Shown)
ElastomericElastomeric Seismic Isolator Seismic Isolator –– LRB or LRB or HDRHDR
Elastomeric Backed SliderElastomeric Backed SliderExample Example HysteresisHysteresis LoopLoop
ConsultingEngineers
Key System Design ParametersKey System Design ParametersGordon WrayGordon Wray
Force
Displacement
K2
Vy
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No Replacement after an Earthquake No Replacement after an Earthquake Ian Aiken Ian Aiken
•• Prototype testing takes the isolators through Prototype testing takes the isolators through 3 or 4 maximum credible earthquakes3 or 4 maximum credible earthquakes
ConsultingEngineers
6 Story Isolated Computer Center –Kobe Japan
ConsultingEngineersBase Isolated Base Isolated –– Computer CenterComputer Center
ConsultingEngineers
6 Story Conventional Office Building Next Block
ConsultingEngineersConventional Office Building Conventional Office Building
ConsultingEngineersEarthquake Force Reduction Earthquake Force Reduction –– 10 10
ConsultingEngineers
Comparison of Applications in the US Comparison of Applications in the US and Japanand Japan
•• US US –– 100 building applications100 building applications
•• Japan Japan -- 1500 building applications1500 building applications
•• Issues include:Issues include:societies attitude to earthquake safety, US focus on first rather than life cycle costs, lack of awareness of the performance of a code designed building
•• Dr. Kani will overview progress in JapanDr. Kani will overview progress in Japan
ConsultingEngineersUS ApplicationsUS Applications
•• 55% Government55% Government•• 45% Private sector45% Private sector•• 60% New Buildings60% New Buildings•• 40% Retrofit of Existing 40% Retrofit of Existing
BuildingsBuildings•• 10 Hospitals10 Hospitals
ConsultingEngineersHospitalsHospitals
USC Teaching Hospital
Long Beach VA Retrofit
San Bernardino County
Los Angeles County
ConsultingEngineers
Government Buildings
Salt Lake City and County South Carolina State Capitol
•• Building will move +/Building will move +/-- 20 to 30 inches20 to 30 inches
•• Piping Piping -- loops and flexible couplersloops and flexible couplers
•• Building separation from adjacent structures Building separation from adjacent structures –– some innovative solutions have been some innovative solutions have been developeddeveloped
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Isolator Locations Isolator Locations New Construction New Construction –– Pat Ryan Pat Ryan
ConsultingEngineersClosure DetailsClosure Details
ConsultingEngineersSan Diego County Emergency Operation CenterSan Diego County Emergency Operation Center
ConsultingEngineers
San Diego County Emergency Operation San Diego County Emergency Operation CenterCenter
ConsultingEngineersUSC HospitalUSC Hospital
ConsultingEngineersUSC HospitalUSC Hospital
ConsultingEngineersSan Bernardino Law & Justice Center
ConsultingEngineersNew San Francisco LibraryNew San Francisco Library
ConsultingEngineers
San Francisco Airport and San Bernardino San Francisco Airport and San Bernardino Hospital Complex Hospital Complex –– 5 Isolated Buildings5 Isolated Buildings
ConsultingEngineersKaiser Data Center Kaiser Data Center
ConsultingEngineersEvans and Sutherland Evans and Sutherland
ConsultingEngineersSome Innovative Framing Schemes - Japan
ConsultingEngineers
ConsultingEngineers
ConsultingEngineers
•• FunctionalityFunctionality
•• Contents ProtectionContents Protection
•• Investment ProtectionInvestment Protection
•• Historic PreservationHistoric Preservation
•• Design EconomyDesign Economy
Retrofit GoalsRetrofit Goals
ConsultingEngineers
Retrofit Design IssuesRetrofit Design IssuesSimin Naaseh and Mason WaltersSimin Naaseh and Mason Walters
•• Capacity of Existing BuildingCapacity of Existing Building
•• Plane of IsolationPlane of IsolationFoundation Level
Basement Level
Top or Mid-Height at Columns
ConsultingEngineersBenefits of Base Isolation RetrofitBenefits of Base Isolation Retrofit
•• With 1600 isolated projects worldwide all the With 1600 isolated projects worldwide all the interface issues have been addressedinterface issues have been addressed
•• Base isolation is most economic method of Base isolation is most economic method of achieving operational performance objective achieving operational performance objective
•• Operational performance is difficult and more Operational performance is difficult and more expensive with conventional designexpensive with conventional design
•• More sophisticated engineering analysis More sophisticated engineering analysis
•• Geotechnical Geotechnical –– need site specific study need site specific study
•• Peer review is required by the code and needs to be done Peer review is required by the code and needs to be done concurrently with the design.concurrently with the design.
ConsultingEngineersSimplified Design Procedure Simplified Design Procedure –– Gordon Wray Gordon Wray
•• Base isolated structure is a structural system Base isolated structure is a structural system that is closest to SDOFthat is closest to SDOF
•• Only structure in US codes that is required to Only structure in US codes that is required to have nonhave non--linear time history analysis linear time history analysis
•• SEAONC PSC believes that the design and SEAONC PSC believes that the design and analysis process must be simplified for more analysis process must be simplified for more widespread use of the technologywidespread use of the technology
•• Debut of an exciting development by PSCDebut of an exciting development by PSC
ConsultingEngineersDesign and Analysis Process Design and Analysis Process –– Troy Morgan Troy Morgan
•• Biggest impact is on structural engineer. They must Biggest impact is on structural engineer. They must determine the amount of movement as quickly as determine the amount of movement as quickly as possible for the architect and MEP team. possible for the architect and MEP team.
•• Architect needs to deal with the separation issues Architect needs to deal with the separation issues and whether or not to feature or hide the fact the and whether or not to feature or hide the fact the building is isolated. building is isolated.
•• Isolation specialist works with other disciplines on Isolation specialist works with other disciplines on architectural, mechanical and electrical details. architectural, mechanical and electrical details.
•• PrePre--selection of the isolation system is desirable on selection of the isolation system is desirable on both hospital and fast track projects. both hospital and fast track projects.