Heintz ATC 63

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ATC-63 Quantification of Building System Performance and Response Parameters

ATC-63

FEMA P-695 Quantification of

Building Seismic Performance

Factors

LATBSDC Annual MeetingMay 7, 2010

ATC-63

FEMA PFEMA P--695 Quantification of695 Quantification of

Building Seismic PerformanceBuilding Seismic Performance

FactorsFactors

LATBSDC Annual MeetingMay 7, 2010

Jon A. Heintz

Applied Technology CouncilDirector of Projects

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Project Context

Background/Scope/Basis of Methodology

Methodology Overview

Example Application to Concrete Moment

Frame Systems

General Findings and Observations

OutlineOutlineOutline

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ATC-63 Project ContextATCATC--63 Project Context63 Project Context

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FEMA funded project

Multi-year effort beginning in 2004

FEMA P695 Quantification of

Building Seismic Performance

Factors (FEMA, 2009)

Genesis is rooted in R-factors

But Seismic Performance Factors

(0, Cd) and design requirementsare covered

ATC-63 Quantification of Building

System Performance and ResponseParameters

ATCATC--63 Quantification of Building63 Quantification of Building

System Performance and ResponseSystem Performance and ResponseParametersParameters

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R-factors were first introduced in 1978

ATC 3-06 Tentative Provisions for theDevelopment of Seismic Regulations for New

Buildings

1988 NEHRP Recommended Provisions forthe Development of Seismic Regulations for

New Buildings

1988 Uniform Building Code (UBC) 1985 UBC and earlier utilized K-factors


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K-factors there were essentially 4

(frame, box, dual system, ductile moment frame)

ATC 3-06 R-factors there were 21

1988 NEHRP Provisions there were 30

Today in ASCE/SEI 7-05 there are 83

Critically important to seismic design

Set seismic design base shear

Account for system ductility and damping during

inelastic response


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But how were they determined?

RR

II

00000000

3/8R3/8RWW

RRWW

CCdd

0.7R0.7R


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That was then, this is now

Advent of Performance Based Seismic DesignSEAOC Vision 2000 (1995)

FEMA 273 NEHRP Guidelines for the SeismicRehabilitation of Buildings (1997)

More than a decade of maturation anddevelopment of advanced analyticalprocedures

We are now attempting to quantify the seismicperformance of buildings


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And asking the question: What performance

goals do our building codes achieve?

0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m.(

T=1.0s)[g]

Maximum Interstory Drift Ratio

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5

Pcollapse

2222

MDLTDDRRTRTOT ++++++++++++====

Objective - replace the smoke with science


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Background, Scope, and BasisBackground, Scope, and BasisBackground, Scope, and Basis

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Project OrganizationProject OrganizationProject OrganizationFEMA

Applied Technology Council

ATC Management Committee

Project Executive Director (Chair)

Project Technical MonitorProject Quality Control Monitor

ATC-63 Project Management Committee

Project Technical Director (Chair)

Five Members

Working GroupsTechnical Consultants

ATC StaffTechnical Support

Administration

Project Review Panel

Twelve Members

PMC MembersCharles Kircher (Chair)

Greg Deierlein Stanford

M. Constantinou Buffalo

John Hooper - MKA

James Harris HA

Allan Porush - URS

Working Groups

Stanford NDA Krawinkler AAC

SUNY NSA/NCA Filiatrault Wood

PRP Members

Maryann Phipps (Chair)

Amr Elnashai - MAE

S.K. Ghosh - SKGA

Ramon Gilsanz- GMS

Ron Hamburger - SGH

Jack Hayes - NIST

Bill Holmes R&C

Richard Klingner - UT

Phil Line - AFPABonnie Manley - AISI

Andre Reinhorn - UB

Chris Rojahn - ATC

Rafael Sabelli - WPM

FEMA

Michael Mahoney

Robert HansonATC Management

Chris Rojahn (PED)

Jon Heintz (PQC)

William Holmes (PTM)

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ATC-63 Project ObjectivesATCATC--63 Project Objectives63 Project Objectives

Primary Create a methodology for determining Seismic

Performance Factors (SPFs) that, when properly

implemented in the design process, will result in the

equivalent earthquake performance for buildings differentlateral-force-resisting systems

Secondary Evaluate a sufficient number of differentlateral-force-resisting systems to provide a basis for Seismic

Code committees (e.g., BSSC PUC) to develop a simpler

set of lateral-force-resisting systems and more rational

SPFs (and related design criteria) that would more reliablyachieve the inherent earthquake safety performance

objectives of building codes

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New Buildings Methodology applies to the seismic-force-resistingsystem of new buildings and may not be appropriate for non-building structures and does not apply to nonstructural systems.

NEHRP Provisions (ASCE 7-05) Methodology is based on design

criteria, detailing requirements, etc. of the NEHRP Provisions (i.e.,ASCE 7-05 as adopted by the BSSC for future NEHRP Provisionsdevelopment) and, by reference, applicable design standards

Life Safety Methodology is based on life safety performance(only) and does not address damage protection and functionalityissues (e.g., I = 1.0 will be assumed)

Structure Collapse Life safety performance is achieved byproviding an acceptably low probability of partial collapse andglobal instability of the seismic-force-resisting system for MCE

ground motions

MCE Ground Motions MCE ground motions are based on thespectral response parameters of the NEHRP Provisions (ASCE 7-05), including site class effects

Scope and Basis of the MethodologyScope and Basis of the MethodologyScope and Basis of the Methodology

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Ground Motion Record SetGround Motion Record SetGround Motion Record Set

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

2.4

0 0.5 1 1.5 2 2.5 3 3.5 4

Period (seconds)

SpectralAcceleration

(g)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Standard

Deviati

on

-Ln

(Sa)

Median Spectrum - Far-Field Set

Far-Field Record Set:R > 10 km

Large Magnitude Events:

Moment magnitude, M > 6.5

Equal Weighting of Events: 2 records per event

Strong Ground Shaking: PGA > 0.2g /PGV > 15 cm/sec

Source Type: Both Strike-Slip and Thrust Fault Sources

Site Conditions: Rock or Stiff Soil Sites, Vs > 180 m/s

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Technical Approach of the MethodologyTechnical Approach of the MethodologyTechnical Approach of the Methodology

Conceptual Framework Methodology incorporatescutting edge (nonlinear/probabilistic) performance-based analysis methods while remaining true to thebasic concepts and definitions of seismic performancefactors ofASCE 7-05and the NEHRP Provisions(e.g., global pushover concept as described in theCommentary of FEMA 450)

ASCE 7-05/NEHRP

Design Provisions

(e.g., base shear)

V = CsW

Performance-Based

Analysis Methods

Probabilistic Collapse

Fragility

Nonlinear (Incremental)

Dynamic Analysis

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Overview of the MethodologyOverview of the MethodologyOverview of the Methodology

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Peer ReviewRequirements

Test DataRequirements

Design InformationRequirements

Analysis

Methods

Ground

Motions

Methodology

Elements of the MethodologyElements of the MethodologyElements of the Methodology

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Notional Flowchart of ProcessNotional Flowchart of ProcessNotional Flowchart of Process

DevelopDesign Rules

DevelopTest Data

Notes

Homework phase

Characterize System

BehaviorDefine Archetypes

YesPeer Review applies

to total processReview and Documentation

P[Collapse] < LimitTrial value of the R

factor acceptable?

Evaluate System PerformanceEvaluate CMR values

(and overstrength)

Perform Pushover

and NDA

Analyze Archetype Models

Design archetypes

(w/trial of RFactor)Develop Archetype Models

No

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Notional Collapse Fragility One Data PointNotional Collapse FragilityNotional Collapse Fragility One Data PointOne Data Point

-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Ac

celeration

(g's)

1989 Loma Prieta - Corralitos (128 deg.)

Scaled Ground

Motion Record

+Joes

Beer!Beer!

Food!Food!

Building

(Joes Bar)

Incipient

Collapse

=

Evaluation of a individual structure (one configuration/setof performance properties) to failure using one ground

motion record scaled to effect incipient collapse

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0 0.05 0.1 0.10

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m.(T

=1.0s)[g]


36 records

Notional Collapse FragilityNotional Collapse FragilityNotional Collapse Fragility

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Notional Collapse FragilityNotional Collapse FragilityNotional Collapse Fragility

Order collapse data from least to greatest

Plot as a cumulative distribution functionProbability versus collapse intensity

0 0.05 0.1 0.10

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m.(

T=1.0s)[g]


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0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0

Collapse Spectral Acceleration (g)

CollapseProbabilit

y

.

Comprehensive Collapse Data

Lognormal Distribution

Notional Collapse Fragility CurveNotional Collapse Fragility CurveNotional Collapse Fragility Curve

50% probabilityof collapse at

SCT = 1.6g

10% probability

of collapse at

SCT = 0.9g (SMT)

Acceptably low

probability of

collapse given MCE

spectral acceleration

CMR Collapse Margin RatioCMR= 1.6g / 0.9g

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Performance EvaluationPerformance EvaluationPerformance Evaluation

Simply

Verify that calculated CMR< acceptable CMR

But

What is an acceptable probability of collapse?

How many data points are enough?What is an appropriate analytical model?

How do we address uncertainty?

Ground motion, Design, Modeling, Testing

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Illustrative ExampleIllustrative ExampleIllustrative Example

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DevelopDesign Rules

DevelopTest Data

Define Archetypes

Yes

Review and Documentation

P[Collapse] < Limit

Evaluate System Performance

Analyze Archetype Models

Develop Archetype Models

No

Reinforced

Concrete Special

Moment Frame

System

Example RC SMF SystemExampleExample RC SMF SystemRC SMF System

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ATC-63 Quantification of Building System Performance and Response Parameters 2

Office occupancy

Frame System

High seismic regions Design Code:

IBC / ACI / ASCE 7

Typical Frame Members

Beams: 32 to 40 deep

Columns: 24x28 to 30x40

Governing Design Parameters

- Beams: minimum strength

- Column size: joint strength

- Column strength: SCWB- Drift: just meets limit

System ConceptionSystem ConceptionSystem Conception

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System ConfigurationSystem ConfigurationSystem ConfigurationSpace Frame Perimeter Frame

Bay Width (e.g., 20 or 30 feet)

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System Design SpaceSystem Design SpaceSystem Design Space

13' (typ.)

15'

12-story

20-story

1-story

2-story

4-story

8-story

3 bays @ 20' 3 bays @ 20' 3 bays @ 20' 3 bays @ 20' 3 bays @ 20' 3 bays @ 20'

Number of Stories

Story Height

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Performance GroupsPerformance GroupsPerformance GroupsPerformance Group Summary

Grouping Criteria

Design Load LevelGroupNo. Basic

Configuration Gravity Seismic

Period

Domain

Number ofArchetypes

PG-1 Short 3

PG-2Max SDC

Long 3

PG-3 Short 3

PG-4

HighMin SDC

Long 3

PG-5 Short 3

PG-6Max SDC

Long 3

PG-7 Short 3

PG-8

Type 1

Low

Min SDCLong 3

20-foot bays

Repeat for 30-foot bays

Space frame

Perimeter frame

High seismic design

Low seismic design

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Deterioration Modes and Collapse

Scenarios

Deterioration Modes and CollapseDeterioration Modes and Collapse

ScenariosScenarios

.

, ,

.

() ()

.

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Deterioration ModesDeterioration ModesDeterioration Modes

A Flexural hinging ofbeam-column elements

B Column compressivefailure

C Beam-column shearfailure

D Joint shear failure EPull-out and bond-slip of rebar at

connections

F Slab-columnconnection punching

shear

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Nonlinear Analysis ModelsNonlinear Analysis ModelsNonlinear Analysis Models

2

Joints with both bond-slipsprings and shear springs

Column bond-slip springs

Lumped plasticitybeam-columns

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Concrete Hinge Model CalibrationConcrete Hinge Model CalibrationConcrete Hinge Model Calibration

-0.1 -0.05 0 0.05 0.1-300

-200

-100

0

100

200

300

ShearF

orce(kN)

Column Drift (displacement/height)

Experimental Results

Model Prediction

Identify and Test KeyParameters:

strength

initial stiffness post-yield stiffness

plastic rotation (capping) capacity

post-capping slope

cyclic deterioration rate

Example Data Set:

250+ columns (PEER database)

flexure & flexure-shear dominant

calibrated to median(characteristic)values

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0 0.05 0.1 0.10

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m.(T

=1.0s)[g]

Maximum Interstory Drift Ratio0 0.05 0.1 0.1

0

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m.(T

=1.0s)[g]


36 recordsSimulation ResultsSimulation ResultsSimulation Results

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Simulation Results: Collapse ModesSimulation Results: Collapse ModesSimulation Results: Collapse Modes

% %

%

**

%

% %

0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m

.(T=1.0

s)[g]


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0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m.(T

=1.0s)[g]


.

2.2

0.3

Simulation Results: Collapse DataSimulation Results: Collapse DataSimulation Results: Collapse Data

MCE = 0.8 g

Mediancol = 2.2g

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Effect of UncertaintiesEffect of UncertaintiesEffect of Uncertainties

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5

CMR

= 0.4

Sa/SMT

> 0.4

FOUR CONTRIBUTORS:

1. Record-to-Record Variability

(RTR= 0.4)

2. Design Requirements

3. Quality of Test Data4. Quality of Analytical Model

2222

MDLTDDRRTRTOT ++++++++++++====

Greater uncertainties will require larger median collapse margins

to satisfy maximum collapse probability at MCE

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ATC-63 Quantification of Building System Performance and Response ParametersATC-63 Quantification of Building System Performance and Response Parameters

Table 3-1 Quality Rating for Design Requirements

Completeness and

Robustness

Confidence in Basis of Design Requirements

High Medium LowHigh. Extensive safeguardsagainst poor behavior. Allimportant design and qualityassurance issues areaddressed.

(A) Superior (B) Good (C) Fair

Medium. Reasonablesafeguards against poorbehavior. Most of theimportant design andquality assurance issuesare addressed.

(B) Good (C) Fair (D) Poor

Low. Questionable

safeguards against poorbehavior. Many importantdesign and qualityassurance issues are notaddressed.

(C) Fair (D) Poor --

Quality RatingsQuality RatingsQuality Ratings

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Total Collapse UncertaintyTotal Collapse UncertaintyTotal Collapse Uncertainty Design Requirements: A-Superior

Test Data: B-Good Nonlinear Model: A-Superior

Uncertainty - Nonlinear Model A - Superior

Uncertainty - Quality of Design RequirementsUncertainty - Quality ofTest Data A - Super. B - Good C - Fair D - Poor

A - Superior 0.55 0.55 0.65 0.80

B - Good 0.55 0.60 0.70 0.85C - Fair 0.65 0.70 0.80 0.90

D - Poor 0.80 0.85 0.90 1.00

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0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sag.m

.(T=1.0

s)[g]


0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Sag.m.

(T=1.0s) [g]

CummulativeP

robabilityofCollapse

Empirical CDF

Lognormal CDF (RTR Var.)Lognormal CDF (RTR + Modeling Var.)

Median = 2.2g

, .

Adjusted Collapse Fragility CurveAdjusted Collapse Fragility CurveAdjusted Collapse Fragility Curve

MCE = 0.8g

CMR = ??

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Acceptable Collapse Margin RatiosAcceptable Collapse Margin RatiosAcceptable Collapse Margin Ratios

Collapse ProbabilityTotal System

Collapse

Uncertainty5% 10%

(ACMR10%)

15% 20%

(ACMR20%)

25%

0.275 1.57 1.42 1.33 1.26 1.20

0.300 1.64 1.47 1.36 1.29 1.22

0.500 2.28 1.90 1.68 1.52 1.40

0.525 2.37 1.96 1.72 1.56 1.42

0.550 2.47 2.02 1.77 1.59 1.45

0.575 2.57 2.09 1.81 1.62 1.47

For any one archetypeOn average per performance group

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Example Results RC SMF SystemExample ResultsExample Results

RC SMF SystemRC SMF System

Design Configuration Computed Collapse Margin Acceptance CheckArch.

Design IDNumber

No. ofStories

Framing /GravityLoads

SeismicSDC

Static CMR c SSF ACMRAccept.ACMR

Pass/Fail

Maximum Seismic (Dmax) and Low Gravity (Perimeter Frame) Designs, 20' Bay Width2069 1 P Dmax 1.6 1.18 16.1 1.34 1.58 1.59 Near Pass

2064 2 P Dmax 1.8 1.50 19.5 1.34 2.01 1.59 Pass

1003 4 P Dmax 1.6 1.61 9.2 1.42 2.29 1.59 Pass

1011 8 P Dmax 1.6 1.25 7.9 1.62 2.02 1.59 Pass

1013 12 P Dmax 1.7 1.45 10.0 1.62 2.35 1.59 Pass

1020 20 P Dmax 1.6 1.66 7.2 1.59 2.64 1.59 Pass

Mean/Acceptable: -- -- 1.7 -- -- 2.15 2.02 Pass

Maximum Seismic (Dmax) and High Gravity (Space Frame) Designs, 20' Bay Width

2061 1 S Dmax 4.0 1.96 16.1 1.34 2.62 1.59 Pass

1001 2 S Dmax 3.5 2.06 14.3 1.34 2.76 1.59 Pass

1008 4 S Dmax 2.7 1.78 9.6 1.42 2.53 1.59 Pass

1012 8 S Dmax 2.3 1.63 6.2 1.55 2.52 1.59 Pass

1014 12 S Dmax 2.1 1.59 5.8 1.53 2.44 1.59 Pass

1021 20 S Dmax 2.0 1.98 9.1 1.62 3.21 1.59 Pass

Mean/Acceptable: -- -- 2.8 -- -- 2.68 2.02 Pass

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RC SMF Example - ConclusionsRC SMF ExampleRC SMF Example --ConclusionsConclusions

A value of R=8 provides an acceptable level

of collapse safety The Methodology is reasonably well-

calibrated to current design provisions

RC SMF systems didnt fail miserably

RC SMF systems didnt pass easily

This was true of all systems tested

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Peer Review ConsiderationsPeer Review ConsiderationsPeer Review Considerations

Implementation involves:

Uncertainty

Judgment

Potential for variation

Peer Review is critical for:Testing

Archetype development

Analytical modelingQuality rating assessment




Analysis

Methods

Ground

Motions

Methodology







Analysis

Methods

Analysis

Methods

Ground

Motions

Ground

Motions

Methodology

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Observations and FindingsObservations and FindingsObservations and Findings

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Methodology was developed considering:

special concrete moment frames

ordinary concrete moment frames

special steel moment frames

wood shear walls

Some trends in our current design process

have become apparent

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Performance assessment is a difficult challenge

fraught with much uncertainty

Buildings located in the near-field have higher

collapse probabilities

Short period buildings have higher collapse

probabilities Collapse performance varies by Seismic Design

Category

Secondary systems influence collapse capacity There is no practical difference in performance

between R=6 and R=6.5

SSS

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SummarySummarySummary

Recommended Methodology provides a rationalbasis for establishing global seismic performancefactors (e.g., Rfactors)

Intended to support and improve Seismic Codes:

Adoption of new systems that must be assigned valuesof seismic performance factors

Improvement of current values of seismic performancefactors of existing systems

Collapse evaluation of a specific building designed

using alternative performance-based methods

FEMA P-695 is now available online and in print

(App. F)

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Thank you!Thank you!Thank you!

Heintz ATC 63

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