1 U.S. Resiliency Council FEMA P-58 Building Seismic Rating Methodology Presented by: Curt B. Haselton, PhD, PE Work by: Full USRC FEMA P-58 Subcommittee Professor of Civil Engineering @ CSU, Chico Co-Founder @ Seismic Performance Prediction Program (SP3) www.hbrisk.com ATC-SEI: 2 nd Conference on Improving the Seismic Performance of Existing Buildings and Other Structures San Francisco, CA | December 10-12, 2015
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FEMA P-58 Building Seismic Rating Methodology · · 2018-04-20U.S. Resiliency Council 1 FEMA P-58 Building Seismic Rating Methodology Presented by: Curt B. Haselton, PhD, PE Work
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U.S. Resiliency Council
FEMA P-58 Building Seismic Rating Methodology
Presented by: Curt B. Haselton, PhD, PEWork by: Full USRC FEMA P-58 Subcommittee
Professor of Civil Engineering @ CSU, ChicoCo-Founder @ Seismic Performance Prediction Program (SP3)
www.hbrisk.com
ATC-SEI: 2nd Conference on Improving the Seismic Performance of Existing Buildings and Other Structures
Standardized and objective methodology Standardized component fragilities and costs Detailed enough to account be building specifics Dig as deep as you like, and decide what data are of use Tool/graphics to communicate with clients (and for reports)
The USRC rating method is based on FEMA P-58, with thresholds for achieving each rating level. There are a few USRC-specific aspects of the FEMA P-58
assessment, such as:• Use of the REDi methodology extension for recovery time.• Use of FEMA 154 checklists for estimating collapse fragility inputs.• Some specific “level of analysis” requirements for each star level.
Injuries and blocking of exit paths unlikelyExpected performance results in conditions unlikely to cause injuries or to keep people from exiting the
building.
The requirements shall be met for 4-star.
The likelihood of a building occupant being fatality injured, considering both building collapse and other non-collapse falling hazards, is less than 0.00003
for a 475-year event.
Egress routes are expected to be intact, with the building meeting the specific requirements below for a 475-year event.
4-starSerious injuries unlikely
Expected performance results in conditions that are unlikely to cause serious injuries.
The likelihood of a building occupant being fatality injured, considering both building collapse and other non-collapse falling hazards, is less than 0.0001
for a 475-year event.
The likelihood of a building occupant being injured, considering both building collapse and other non-collapse falling hazards, is less than 0.02 for
a 475-year event.
3-starLoss of life unlikely
Expected performance results in conditions that are unlikely to cause loss of life.
The likelihood of a building occupant being fatally injured, considering both building collapse and other non-collapse falling hazards, is less than 0.0004
for a 475-year event.
2-starLoss of life possible in isolated locations
Expected performance results in partial collapse or falling objects … loss of life at some locations …
The likelihood of a building occupant being fatally injured, considering only building collapse, is less than 0.004 for a 475-year event.
Fatalities due to falling hazards are not considered.
1-starLoss of life likely in the building
Expected performance results in building collapse which has a high potential for deaths …
The building was evaluated but did not meet the 2-star rating criteria.
The REDi method is used for the USRC Recovery Time rating. The REDi method has three primary advantages over the basic FEMA
P-58 repair time method:3) It includes time for impeding factors that delay the onset of repair (which
the Beta testing showed to be critical for the repair numbers to make sense). [for USRC rating, all impeding factors are included other than off-site power]
The USRC rating method allows “any rational method” to be used for estimating the structural responses. Option #1: Response-history analysis (but conservative if don’t include
gravity framing and other non-structural component stiffnesses) Option #2: FEMA P-58 Simplified Method, but limited to:
• Buildings up to 15 stories• Regular buildings (e.g. no weak-story irregularities)
Option #3: Simplified Method extended for weak-story (beta in SP3). New options available soon (in the Seismic Performance Prediction
Program), with funding from the National Science Foundation:• Enhanced Simplified Method (modal-based, up to 40+ stories, handles weak-story
irregularities, better variability estimation)• Improved Simplified Method for shear walls (need to use chord rotation for
damage to walls, using story drift is conservative)• Mean response inputs for Simplified Method (e.g. use response spectrum analysis).
The FEMA P-58 methods and databases support almost all structural system types, but a few are not well supported. Supported: Steel moment frame (pre- and post-Northridge) Steel braced frame and BRB RC shear walls (flexural and squat) RC frames (new and old) Reinforced masonry (with rigid diaphragms) Base isolated (but need RHA or RSA) Supplemental damped (but need RHA, RSA, or Enhanced Simplified Method)
Not currently supported (but have first three on the work plan): Wood light frame (effects of non-structural components) Tilt-up (response estimation and fragilities) Precast URM
This is an exciting time of new developments:• FEMA P-58: Provides building-specific estimates of loss, repair time,
and fatality/injury (with cause-and-effect level of detail).• USRC Ratings: Provides a standard way to communicate
performance.
Question: As a structural engineering profession, what will we do with these new developments? How can we leverage this for more resilient infrastructure?
• Advanced design including 3Ds - safety + loss + recovery time• Advanced retrofit including 3Ds - safety + loss + recovery time• Advanced loss assessments (PML, more detailed SRA, etc.)• Advanced risk assessments for insurance• Other?