atc-63 fema pfema p--695 quantification of building...

ATC-63 Quantification of Building System Performance and Response Parameters

ATC-63

FEMA P-695 Quantification of

Building Seismic Performance

Factors

LATBSDC Annual Meeting

May 7, 2010

ATC-63

FEMA PFEMA P--695 Quantification of 695 Quantification of

Building Seismic Performance Building Seismic Performance

FactorsFactors

LATBSDC Annual Meeting

May 7, 2010

Jon A. Heintz

Applied Technology Council

Director of Projects


• Project Context

• Background/Scope/Basis of Methodology

• Methodology Overview

• Example Application to Concrete Moment

Frame Systems

• General Findings and Observations

OutlineOutlineOutline


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


• 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

(Ω0, Cd) and design requirements

are covered

ATC-63 Quantification of Building

System Performance and Response

Parameters

ATCATC--63 Quantification of Building 63 Quantification of Building

System Performance and Response System Performance and Response

ParametersParameters


• R-factors were first introduced in 1978

ATC 3-06 Tentative Provisions for the

Development of Seismic Regulations for New

Buildings

• 1988 NEHRP Recommended Provisions for

the Development of Seismic Regulations for

New Buildings

• 1988 Uniform Building Code (UBC)

• 1985 UBC and earlier utilized K-factors



• 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



• But how were they determined?

RR

II

ΩΩΩΩΩΩΩΩ00000000

3/8R3/8RWW

RRWW

CCdd

0.7R0.7R



• That was then, this is now

• Advent of Performance Based Seismic DesignSEAOC Vision 2000 (1995)

FEMA 273 NEHRP Guidelines for the Seismic Rehabilitation of Buildings (1997)

• More than a decade of maturation and development of advanced analytical procedures

• We are now attempting to quantify the seismic performance of buildings



• 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

Sa

g.m

.(T=

1.0

s)[

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

Pco

llap

se

2222

MDLTDDRRTRTOT ββββββββββββββββββββ ++++++++++++====

• Objective - replace the smoke with science



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


Project OrganizationProject OrganizationProject OrganizationFEMA

Applied Technology Council

ATC Management Committee

Project Executive Director (Chair)

Project Technical Monitor

Project Quality Control Monitor

ATC-63 Project Management Committee

Project Technical Director (Chair)

Five Members

Working Groups

Technical Consultants

ATC Staff

Technical Support

Administration

Project Review Panel

Twelve Members

PMC Members

Charles 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 - AFPA

Bonnie 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)


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

• Primary – Create a methodology for determining Seismic

Performance Factors (SPF’s) “that, when properly

implemented in the design process, will result in the

equivalent earthquake performance for buildings different

lateral-force-resisting systems”

• Secondary – Evaluate a sufficient number of different

lateral-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

SPF’s (and related design criteria) that would more reliably

achieve the inherent earthquake safety performance

objectives of building codes


• New Buildings – Methodology applies to the seismic-force-resisting system 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 functionality issues (e.g., I = 1.0 will be assumed)

• Structure Collapse – Life safety performance is achieved by providing an acceptably low probability of partial collapse and global instability of the seismic-force-resisting system for MCE ground motions

• MCE Ground Motions – MCE ground motions are based on the spectral 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


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)

Spectral Acceleration (g)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Standard Deviation - 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


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

• Conceptual Framework – Methodology incorporates cutting edge (nonlinear/probabilistic) performance-based analysis methods while remaining true to the basic concepts and definitions of seismic performance factors of ASCE 7-05 and the NEHRP Provisions(e.g., global pushover concept as described in the Commentary 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


Overview of the MethodologyOverview of the MethodologyOverview of the Methodology


Peer ReviewRequirements

Test Data Requirements

Design Information Requirements

Analysis

Methods

Ground

Motions

Methodology

Elements of the MethodologyElements of the MethodologyElements of the Methodology


Notional Flowchart of ProcessNotional Flowchart of ProcessNotional Flowchart of Process

Develop

Design Rules

Develop

Test 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 NDAAnalyze Archetype Models

Design archetypes

(w/trial of R Factor)Develop Archetype Models

No


Notional Collapse Fragility – One Data PointNotional Collapse Fragility Notional 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)

Acceleration (g's)

1989 Loma Prieta - Corralitos (128 deg.)

Scaled Ground

Motion Record

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=

Evaluation of a individual structure (one configuration/set

of performance properties) to failure using one ground

motion record scaled to effect incipient collapse


-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=-0.6

-0.3

0

0.3

0.6

0 2 4 6 8 10 12 14 16 18 20

Time (Seconds)

Acceleration (g's)


Ground Motion

+Joe’s

Beer!Beer!

Food!Food!

Building

(Joe’s Bar)

Incipient

Collapse

=

Notional Collapse Fragility – Comprehensive DataNotional Collapse Fragility Notional Collapse Fragility –– Comprehensive DataComprehensive Data

Robust analytical

models of building

configuration/performance

properties evaluated with

representative earthquake records

Comprehensive

collapse data


0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sa

g.m

.(T=

1.0

s)[

g]


36 records

Notional Collapse FragilityNotional Collapse FragilityNotional Collapse Fragility


Notional Collapse FragilityNotional Collapse FragilityNotional Collapse Fragility

• Order collapse data from least to greatest

• Plot as a cumulative distribution function

Probability versus collapse intensity

0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sa

g.m

.(T=

1.0

s)[

g]



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)

Collapse Probability .

Comprehensive Collapse Data

Lognormal Distribution

Notional Collapse Fragility CurveNotional Collapse Fragility CurveNotional Collapse Fragility Curve

50% probability

of 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 Ratio

CMR = 1.6g / 0.9g


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


Illustrative ExampleIllustrative ExampleIllustrative Example


Develop

Design Rules

Develop

Test 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 SystemExample Example –– RC SMF SystemRC SMF System

ATC-63 Quantification of Building System Performance and Response Parameters27

• Office occupancy

• Frame System

• High seismic regions

• Design Code: IBC / ACI / ASCE 7

Typical Frame Members

Beams: 32” to 40” deep

Columns: 24”x28” to 30”x40”

Governing Design Parameters

- Beams: minimum strength

- Column size: joint strength

- Column strength: SCWB

- Drift: just meets limit

8 inch PT slab

System ConceptionSystem ConceptionSystem Conception


System ConfigurationSystem ConfigurationSystem Configuration

Space Frame Perimeter Frame

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


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


Performance GroupsPerformance GroupsPerformance Groups

Performance Group Summary

Grouping Criteria

Design Load Level Group

No. Basic Configuration Gravity Seismic

Period

Domain

Number of

Archetypes

PG-1 Short ≥ 3

PG-2 Max SDC

Long ≥ 3

PG-3 Short ≥ 3

PG-4

High

Min SDC Long ≥ 3

PG-5 Short ≥ 3

PG-6 Max SDC

Long ≥ 3

PG-7 Short ≥ 3

PG-8

Type 1

Low

Min SDC Long ≥ 3

20-foot bays

Repeat for 30-foot bays

Space frame

Perimeter frame

High seismic design

Low seismic design


Deterioration Modes and Collapse

Scenarios

Deterioration Modes and Collapse Deterioration Modes and Collapse

ScenariosScenarios

1. Deterioration Modes of RC Elements

- Shear, flexure, joint degradation

2. Building System Collapse Scenarios

- Sidesway Collapse (SC)

- Loss in Vertical Load Carrying Capacity (LVCC)

3. Likelihood of Collapse Scenarios


Deterioration ModesDeterioration ModesDeterioration Modes

A Flexural hinging of beam-column elements

B Column compressive failure

C Beam-column shear failure

D Joint shear failure

E Pull-out and bond-slip of rebar at

connections

F Slab-column connection punching

shear


Nonlinear Analysis ModelsNonlinear Analysis ModelsNonlinear Analysis Models

2D multistory model to capture likely sidesway

collapse scenarios and component behavior

Joints with both bond-slip springs and shear springs

Column bond-slip springs

Lumped plasticity beam-columns


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

Sh

ea

r F

orc

e (

kN

)

Column Drift (displacement/height)

Experimental Results

Model Prediction

Identify and Test Key Parameters:

• 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


0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sa

g.m

.(T=

1.0

s)[

g]

Maximum Interstory Drift Ratio0 0.05 0.1 0.15

0

0.5

1

1.5

2

2.5

3

3.5

4

Sa

g.m

.(T=

1.0

s)[

g]


36 records

Simulation ResultsSimulation ResultsSimulation Results


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

40% of collapses27% of collapses

17% of collapses

**Predicted by Static Pushover

12% of collapses

5% of collapses 2% of collapses

0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sa

g.m

.(T=

1.0

s)[

g]


Incremental

Dynamic Analysis


0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4S

ag

.m.(T

=1

.0s)[

g]


Capacity Stats.:

Median = 2.2g

σLN = 0.36

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

MCE = 0.8 g

Mediancol = 2.2g


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

(ββββRTR = 0.4)

2. Design Requirements

3. Quality of Test Data

4. Quality of Analytical Model

2222

MDLTDDRRTRTOT ββββββββββββββββββββ ++++++++++++====

Greater uncertainties will require larger median collapse margins

to satisfy maximum collapse probability at MCE

Collapse

Probability at

MCE?

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 Low

High. Extensive safeguards against poor behavior. All important design and quality assurance issues are addressed.

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

Medium. Reasonable safeguards against poor behavior. Most of the important design and quality assurance issues are addressed.

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

Low. Questionable safeguards against poor behavior. Many important design and quality assurance issues are not addressed.

(C) Fair (D) Poor --

Quality RatingsQuality RatingsQuality Ratings


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 Requirements Uncertainty - Quality of Test 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 0.85

C - Fair 0.65 0.70 0.80 0.90

D - Poor 0.80 0.85 0.90 1.00


0 0.05 0.1 0.150

0.5

1

1.5

2

2.5

3

3.5

4

Sa

g.m

.(T=

1.0

s)[

g]


Incremental

Dynamic Analysis

Results0 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]

Cu

mm

ula

tiv

e P

rob

ab

ility

of

Co

llap

se

Empirical CDF

Lognormal CDF (RTR Var.)

Lognormal CDF (RTR + Modeling Var.)

Median = 2.2g

σσσσLN, Total = 0.36

Adjusted Collapse Fragility CurveAdjusted Collapse Fragility CurveAdjusted Collapse Fragility Curve

MCE = 0.8g

CMR = ??


Acceptable Collapse Margin RatiosAcceptable Collapse Margin RatiosAcceptable Collapse Margin Ratios

Collapse Probability Total System

Collapse

Uncertainty 5% 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


Example Results – RC SMF SystemExample Results Example Results –– RC SMF SystemRC SMF System

Design Configuration Computed Collapse Margin Acceptance Check Arch.

Design ID Number

No. of Stories

Framing / Gravity Loads

Seismic SDC

Static Ω CMR µc SSF ACMR Accept. ACMR

Pass/Fail

Maximum Seismic (Dmax) and Low Gravity (Perimeter Frame) Designs, 20' Bay Width

2069 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


RC SMF Example - ConclusionsRC SMF Example RC 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 didn’t fail miserably

RC SMF systems didn’t pass easily

• This was true of all systems tested


Peer Review ConsiderationsPeer Review ConsiderationsPeer Review Considerations

• Implementation involves:

Uncertainty

Judgment

Potential for variation

• Peer Review is critical for:

Testing

Archetype development

Analytical modeling

Quality rating assessment




Analysis

Methods

Ground

Motions

Methodology







Analysis

Methods

Analysis

Methods

Ground

Motions

Ground

Motions

Methodology


Observations and FindingsObservations and FindingsObservations and Findings



• 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…



• 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


SummarySummarySummary

• Recommended Methodology provides a rational basis for establishing global seismic performance factors (e.g., R factors)

• Intended to support and improve Seismic Codes:

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

Improvement of current values of seismic performance factors 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)


Thank you!Thank you!Thank you!

atc-63 fema pfema p--695 quantification of building...

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