Transcript Slide 1
Development of Performance-based Seismic
Design Standards & Criteria
Ronald O. Hamburger, SE, SECB
Senior Principal
Simpson Gumpertz & Heger
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Code Procedures
• Require buildings have complete
structural systems
• Require systems have sufficient
strength to resist specified forces
2003
• Limit permissible drifts under
specified forces
• Require members and connections
be “detailed” prescriptively
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Building Codes Imply Performance
Ability to resist frequent, minor
earthquakes without damage
2003
100 yrs
Ability to resist infrequent,
moderate earthquakes with
limited structural and
nonstructural damage
500 yrs
Ability to resist worst
earthquakes ever likely to occur
without collapse or major life
safety endangerment
2,500 yrs
Performance is not guaranteed
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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 intended
to prevent . . . or to prohibit any design or
method of construction. . . provided that any
such alternative has been approved.
An alternative. . . design shall be approved
where the building official finds that the
proposed design is satisfactory and
complies with the intent of the provisions of
this 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)
Seismic
Evaluation of
Buildings
Rehabilitation
Procedures to design building
upgrades to achieve
desired 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
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ASCE-31
Seismic
Rehabilitation of
Buildings
ASCE-41
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Selecting Performance
Present Generation
Joe’s
Joe’s
Beer!
Food!
Operational
Beer!
Food!
Immediate
Occupancy
Beer!
Food!
Life
Safety
Collapse
Prevention
Operational – negligible impact on building
Immediate Occupancy – building is safe to occupy but
possibly not useful until cleanup and repair has occurred
Life Safe – building is safe during event but possibly not
afterward
Collapse Prevention – building is on verge of
collapse, probable total loss
Code-equivalent Performance
Joe’s
Beer!
Food!
Frequent event (varying between 50- and 100year return periods)
Immediate
Occupancy
DBE
MCE
Beer!
Food!
Life
Safety
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Collapse
Prevention
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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 design
A new approach
Owner
Designer
Building Official
Select
Performance
Objectives
Develop
Preliminary
Design
Assess
Performance
Capability
Revise
Design
No
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Does
Performance
Meet
Objectives?
Building
Official
&
Peer
Reviewers
Yes
Done
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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
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