Www.sgh.com © Simpson Gumpertz & Heger Inc. 1 Development of Performance-based Seismic Design Standards & Criteria Ronald O. Hamburger, SE, SECB Senior.

www.sgh.com © Simpson Gumpertz & Heger Inc.

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Development of Performance-based Seismic Design Standards & Criteria

Ronald O. Hamburger, SE, SECB

Senior Principal

Simpson Gumpertz & Heger


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• Limit permissible drifts under specified forces

• Require buildings have complete structural systems

Code Procedures

• Require systems have sufficient strength to resist specified forces

• Require members and connections be “detailed” prescriptively

2003


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Building Codes Imply Performance Ability to resist frequent, minor

earthquakes without damage

Ability to resist infrequent, moderate earthquakes with limited structural and nonstructural damage

Ability to resist worst earthquakes ever likely to occur without collapse or major life safety endangerment

100 yrs

500 yrs

2,500 yrs

Performance is not guaranteed

2003


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Building Codes & Peformance Warranties

If a building is affected by an extreme event and performs poorly: There is an expectation of how the building should

have performed but no implied warranty

The only warranty is that the engineer complied with the standard of care For most buildings, demonstration that a design was

performed in accordance with the building code will provide adequate proof of conformance to the standard of care


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Code Basis for Performance-based Design

Section 104-

“The provisions of this code are not intendedto prevent . . . or to prohibit any design ormethod of construction. . . provided that anysuch alternative has been approved.

An alternative. . . design shall be approvedwhere the building official finds that theproposed design is satisfactory andcomplies with the intent of the provisions ofthis code.”


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First Generation Standards are Available ASCE/SEI has standardized FEMA

guideline documents on:: Seismic Evaluation

Predict types of damage a building would experience in future events (based on FEMA178)

Rehabilitation Procedures to design building

upgrades to achievedesired performance (based on FEMA 356)

Though not directly recognized by the building codes, these standards are being used as the basis for Performance-based design of new buildings and seismic retrofit

SeismicEvaluation ofBuildings

ASCE-31

SeismicRehabilitation ofBuildings

ASCE-41

Selecting PerformancePresent Generation

Joe’s

Beer!Beer!Food!Food!

Operational

Operational – negligible impact on building


Joe’s

Beer!Beer!Food!Food!Beer!Beer!Food!Food!

Joe’sJoe’s

ImmediateOccupancy

Immediate Occupancy – building is safe to occupy butpossibly not useful until cleanup and repair has occurred


Joe’s


Joe’s

LifeSafety

Life Safe – building is safe during event but possibly notafterward

CollapsePrevention

Collapse Prevention – building is on verge of collapse, probable total loss


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Code-equivalent Performance


Joe’s


Joe’sJoe’s

ImmediateOccupancy

Frequent event (varying between 50- and 100- year return periods)


Joe’s


Joe’s

LifeSafety

DBE

CollapsePrevention

MCE


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Next Generation Standards are Presently Under Development

ATC-58 Project 10 year program funded by FEMA Develop next-generation criteria applicable to design

of new buildings and upgrade of existing buildings New performance definitions

Performance expressed in terms of the probability of incurring:

Direct economic loss (repair/replacement cost)

Casualties (deaths & serious injuries) Downtime (loss of use)

Direct consideration of uncertainty in ground shaking, structural response, damage and the consequences of damage


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2 Phase Project Execution

Phase 1 Development of a performance assessment

methodology that can be used to predict the probability of incurring the various losses, as a function of specific design decisions

Presently 35% complete

Phase 2 Development of procedures for designing buildings

for desired performance Establishment of performance provided by current

prescriptive procedures Assessment of adequacy of performance Development of improved prescriptive methods

that will provide desired performance


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Performance-based designA new approach

SelectPerformanceObjectives

SelectPerformanceObjectives

DevelopPreliminary

Design

DevelopPreliminary

Design

AssessPerformance

Capability

AssessPerformance

Capability

DoesPerformance

MeetObjectives?

DoesPerformance

MeetObjectives?

DoneDone

ReviseDesign

No

ReviseDesign

No

Owner

Designer

Building Official

YesYes

BuildingOfficial

&Peer

Reviewers


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2 Phase Project Execution

Phase 2 Development of procedures for designing buildings

for desired performance Establishment of performance provided by current

prescriptive procedures Assessment of adequacy of performance Development of guidance on selection of

structural systems, strength, stiffness, etc. that is likely to be able to meet performance goals

Development of improved prescriptive methods that will provide desired performance

Www.sgh.com © Simpson Gumpertz & Heger Inc. 1 Development of Performance-based Seismic Design Standards & Criteria Ronald O. Hamburger, SE, SECB Senior.

Documents

building beer

building upgrades

performance ability

yrs performance

building official finds

development of performance

desired performance

proposed design