fema p-58 building seismic rating methodology · · 2018-04-20u.s. resiliency council 1 fema p-58...

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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

San Francisco, CA | December 10-12, 2015

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Overview of USRC FEMA P-58 Rating Method

This is a methodology to compute a USRC rating based on outputs from a FEMA P-58 analysis.

This includes both analysis requirements and rules for translating the FEMA P-58 results into a USRC rating.

This methodology was created by the FEMA P-58 Ratings subcommittee of the USRC Technical Advisory Committee (TAC).

Co-chairs: Brian McDonald and Curt Haselton

Participants: Many USRC members participated both on the committee and in running validation studies.

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Outline of Presentation

Overview of FEMA P-58 Methodology

USRC Rating approach based on FEMA P-58:

Articulation of FEMA P-58 results to a rating

FEMA P-58 analysis requirements

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P-58 is a performance prediction methodology (10 years in the making, $12M budget, some further development ongoing)

P-58 is tailored for building-specific analysis (in contrast to other available methods for building classes, e.g. HAZUS, ATC-13)

FEMA P-58 output results:• Repair costs• Fatalities & injuries • Repair time & red tagging

Overview of FEMA P-58

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Overview of FEMA P-58

Ground Motion Hazard

Component DamageEconomic Loss

Casualties

Repair Time

Structural Response

[Source: Some graphics from presentation by Ron O. Hamburger on FEMA P-58.]

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FEMA P-58: Methodology

Hazard and Ground Motions• Soil and hazard curve• Ground motions (if needed)

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Structural Responses• Option #1: Response-history• Option #2: Simplified method

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Damage Prediction• Contents (str. and non-str.)• Fragility curves

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Loss Estimation (loss curves) and other consequences

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Loss Estimation (loss curves) and other consequences

Tens of thousands of Monte Carlo simulations

The simulations provide detailed statistical

information on building performance.

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37%32%

7%1% 1% 2% 1%

19%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

StructuralComponents

Partitions InteriorFinishes

Cladding Plumbing andHVAC

OtherComponents

Collapse Residual Drift

Loss Contributions by Component Type for a 475 Year Ground Motion

Total Average Loss: 15%

Average Repair Cost (8-story concrete frame, LA):

FEMA P-58: Output Examples

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6.0 6.3

9.2

0

2

4

6

8

10

12

14

REDi Re-Occupancy REDi Functional Recovery REDi Full Recovery

MO

NTH

S

Repair Time Output at a 475 Year Earthquake

Average REDi Repair Time (8-story concrete frame, LA):


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Safety (fatalities and injuries) (8-story concrete frame, LA):

1.3

0.0 0.0 0.0

1.3

0.00.0

0.5

1.0

1.5

2.0

2.5

3.0

Injuries (FromFalling Hazards)

Fatalities (FromFalling Hazards)

Injuries (FromCollapse)

Fatalities (FromCollapse)

Total Injuries Total Fatalities

Mean Casualties at a 475 Year Earthquake

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• Dig as deep as you like…


37% 32%

7%1% 1% 2% 1%

19%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

StructuralComponents

Partitions InteriorFinishes

Cladding Plumbingand HVAC

OtherComponents

Collapse ResidualDrift

Loss Contributions by Component Type for a 500 Year Ground Motion

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FEMA P-58: Benefits

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)

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Outline of Presentation

Overview of FEMA P-58 Methodology

USRC Rating approach based on FEMA P-58:

Articulation of FEMA P-58 results to a rating

FEMA P-58 analysis requirements

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USRC FEMA P-58 Rating: Overview

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.

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Rating requirements for Repair Costs:

Rating Expected Repair Cost Detailed FEMA P-58 Rating Criteria

5-starMinimal damage.

Repair Cost likely less than 5% of building replacement cost

The mean repair cost in a 475-year event is less than 5% of building replacement cost.

4-starModerate damage.

Repair Cost likely less than 10% of building replacement cost.


3-starSignificant damage.



2-starSubstantial damage.



1-starSevere damage.

Repair Cost likely greater than 40% of building replacement cost.

The mean repair cost in a 475-year event is greater than or equal to 40% of building

replacement cost.


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Rating requirements for Recovery Time:

Rating Expected Recovery Time Detailed FEMA P-58 Rating Criteria

5-starImmediate to days.

The expected performance will likely result in people being able to quickly re-enter…

The median recovery time after a 475-year event is less than 5 days.

4-starWithin days to weeks.

The expected performance may result in delay … from days to weeks…

The median recovery time after a 475-year event is less than 4 weeks.

3-starWithin weeks to months.

The expected performance may result in delay … from weeks to months…

The median recovery time after a 475-year event is less than 6 months.

2-starWithin months to a year.

Expected performance may result in delay … from for months to a year.

The median recovery time after a 475-year event is less than one year.

1-starMore than a year

Expected performance may result in delay … for at least one year or more.

The median recovery time after a 475-year event is greater than one year.


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Rating requirements for Safety:

Rating Expected Safety Detailed FEMA P-58 Rating Criteria

5-star

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


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


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.


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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:1) It separates types of damage into “repair classes,”

which define what repairs are required for: Re-occupancy Functional Recovery [used for USRC rating] Full Recovery

USRC FEMA P-58 Rating: REDi

[Source: REDi Guidelines, 2013.]

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P-58 repair time method:2) It creates a repair sequence to estimate repair

time (rather than using “serial” and “parallel” bounds).




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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]



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The FEMA P-58 Methodology requires that the user input a collapse fragility curve for the building. The USRC FEMA P-58

subcommittee:• felt that user guidance

was needed here, and• adopted the FEMA 154

checklists to estimate the collapse fragility curve (details in the implementation manual).

USRC FEMA P-58 Rating: FEMA 154 for Collapse

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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).

USRC FEMA P-58 Rating: Structural Responses

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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

USRC FEMA P-58 Rating: Structural Systems

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Residual drifts: Excluded for lower ratings, included for higher. Building component inventories: Level of scrutiny depends

on rating being achieved.

USRC FEMA P-58 Rating: Other Requirements

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What Will We Do About This?

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?

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Questions/Comments?

Questions and Discussion?

Please contact me if you have any questions or if you need any additional information.

Contact Information:• E-mail: [email protected], [email protected]

• Cell: (530) 514-8980

• Haselton Baker Risk Group (SP3): www.hbrisk.com

• CSU Chico: www.csuchico.edu/structural

fema p-58 building seismic rating methodology · · 2018-04-20u.s. resiliency council 1 fema p-58...

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