Heintz ATC 63

ATC-63

FEMA P -695 Quantification of P-695 Building Seismic Performance Factors LATBSDC Annual Meeting May 7, 2010 Jon A. Heintz Applied Technology Council Director of Projects

ATC-63 Quantification of Building System Performance and Response Parameters

Outline • • • •

Project Context Background/Scope/Basis of Methodology Methodology Overview Example Application to Concrete Moment Frame Systems • General Findings and Observations


ATC -63 Project Context ATC-63


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

ATC -63 Project Context ATC-63 • 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 ATC-63 Quantification of Building System Performance and Response Parameters

ATC -63 Project Context ATC-63 • 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 ATC-63 Quantification of Building System Performance and Response Parameters

ATC -63 Project Context ATC-63 • But how were they determined?

R RW

Ω0 I

3/8RW 0.7R Cd


ATC -63 Project Context ATC-63 • That was then, this is now • Advent of Performance Based Seismic Design SEAOC 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 ATC-63 Quantification of Building System Performance and Response Parameters

ATC -63 Project Context ATC-63 • And asking the question: What performance goals do our building codes achieve? 4

3.5

2

Sa

g.m.

(T=1.0s)[g]

3

2.5

1.5

1

0.5

0 0

0.05

0.1

0.15

Maximum Interstory Drift Ratio

1 0.9 0.8

Pcollapse

0.7 0.6 0.5

2 2 2 2 + β DR + β TD + β MDL βTOT = β RTR

0.4 0.3 0.2 0.1 0 0

1

2

3

4

5

• Objective - replace the smoke with science ATC-63 Quantification of Building System Performance and Response Parameters

Background, Scope, and Basis


FEMA

Project Organization FEMA

Michael Mahoney Robert Hanson

Applied Technology Council

PRP Members

ATC Management Chris Rojahn (PED) Jon Heintz (PQC) William Holmes (PTM) PMC Members Charles Kircher (Chair) Greg Deierlein – Stanford M. Constantinou – Buffalo John Hooper - MKA James Harris – HA Allan Porush - URS

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

Project Review Panel Twelve Members

Working Groups Technical Consultants

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

ATC Staff Technical Support Administration

Working Groups Stanford – NDA Krawinkler – AAC SUNY – NSA/NCA Filiatrault – Wood ATC-63 Quantification of Building System Performance and Response Parameters

ATC -63 Project Objectives ATC-63 • 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 ATC-63 Quantification of Building System Performance and Response Parameters

Scope and Basis of the Methodology • New Buildings – Methodology applies to the seismic-force-resisting system of new buildings and may not be appropriate for nonbuilding 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 Provisions development) 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 705), including site class effects ATC-63 Quantification of Building System Performance and Response Parameters

Ground Motion Record Set 2.4

1.2

• •

Far-Field Record Set: R > 10 km Large Magnitude Events: Moment magnitude, M > 6.5

Spectral Acceleration (g)

2

1.0

1.8 1.6

0.8

1.4 1.2

0.6

1 0.8

0.4

0.6 0.4

0.2

Standard Deviation - Ln (Sa)

Median Spectrum - Far-Field Set

2.2

0.2 0

0.0 0

0.5

1

1.5

2

2.5

3

3.5

4

Period (seconds)

•

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 ATC-63 Quantification of Building System Performance and Response Parameters

Technical Approach of the Methodology • Conceptual Framework – Methodology incorporates cutting edge (nonlinear/probabilistic) performancebased 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) Performance-Based Analysis Methods ASCE 7-05/NEHRP Design Provisions (e.g., base shear) V = CsW

Probabilistic Collapse Fragility Nonlinear (Incremental) Dynamic Analysis


Overview of the Methodology


Elements of the Methodology

Ground Motions

Analysis Methods

Methodology

Test Data

Design Information

Requirements

Requirements

Peer Review Requirements ATC-63 Quantification of Building System Performance and Response Parameters

Notional Flowchart of Process Develop Test Data

No

Develop Design Rules

Notes “Homework” phase

Define Archetypes

Characterize System Behavior

Develop Archetype Models

Design archetypes (w/trial of R Factor)

Analyze Archetype Models

Perform Pushover and NDA

Evaluate System Performance

Evaluate CMR values (and overstrength)

P[Collapse] < Limit

Trial value of the R factor acceptable?

Yes

Review and Documentation

Peer Review applies to total process


Notional Collapse Fragility – One Data Point Building (Joe’s Bar)

Incipient Collapse Scaled Ground Motion Record

+

Joe’s Beer! Food!

Acceleration (g's)

0.6

1989 Loma Prieta - Corralitos (128 deg.)

0.3

=

0 -0.3 -0.6 0

2

4

6

8 10 12 Time (Seconds)

14

16

18

20

Evaluation of a individual structure (one configuration/set of performance properties) to failure using one ground motion record scaled to effect incipient collapse ATC-63 Quantification of Building System Performance and Response Parameters

Notional Collapse Fragility – Comprehensive Data Incipient Building Collapse (Joe’s Bar) Incipient Building Collapse (Joe’s Bar) Incipient Building Ground Motion Collapse (Joe’s Bar) Incipient Building Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Beer! Ground Motion Collapse (Joe’s Bar) Incipient Food! Building Joe’s Beer! Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Food!Beer! Ground Motion Collapse (Joe’s Bar) Incipient Food! Building Joe’s Beer! Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Food!Beer! Ground Motion Collapse (Joe’s Bar) Incipient Food! Building Joe’s Beer! Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Food!Beer! Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Food!Beer! Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Food!Beer! Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Food!Beer! Ground Motion Collapse (Joe’s Bar) Incipient Food! Building Joe’s Beer! Ground Motion Collapse (Joe’s Bar) Incipient Building Joe’s Food!Beer! Ground Motion Collapse (Joe’s Bar) Incipient Food! Building Joe’s Beer! Ground Motion Collapse (Joe’s Bar) Joe’s Food!Beer! Ground Motion Joe’s Food!Beer! Ground Motion Joe’s Food!Beer! Joe’s Food!Beer!

Comprehensive collapse data


0.3


4

-0.6

+

0

0.6 6


0.3

2

0

4

-0.3 -0.6

+

0

18

=

0.6 6

14

16

2


0

4

-0.6

+

0

18

0.6 6

14

16

2


0

4

-0.6

+

0

18

0.6 6

14

16

2


0

4

-0.6

+

0

18

0.6 6

14

16

2

0


4

-0.6

+

0

18

0.6 6

14

16

2


0

4

-0.6

+

0

18

0.6 6

14

16


0

4

-0.3 -0.6

+

0

0.6 6

14

16

0

4

-0.6

0

18

0.6 6

14

16

2


0

4

-0.6

+

0

18

0.6 6

14

16


0

4

-0.3 -0.6

+

0

18

=

0.6 6

14

16

2


0

4

-0.6

+

0

Food! Beer! Food!

18

=

0.6 6

14

16

0


4

-0.6

+

0

18

=

0.6 6

14

16

2

0


4

-0.6

+

0

18

0.6 6

14

16

0


4

18

=

20

=


0.3

2

20


0.3

-0.3

=

20


0.3

2

-0.3

20


0.3

-0.3

20


0.3

2

20


0.3

-0.3

=

20


0.3

2

=

20


-0.3

+

Robust analytical models of building configuration/performance properties evaluated with representative earthquake records

18


0.3

2

=

20


0.3

-0.3

=

20


0.3

-0.3

=

20


0.3

-0.3

=

20


0.3

-0.3

=

20


0.3

-0.3

=

20

Acceleration (g's)

0

16

Acceleration (g's)

2

-0.3

14


Acceleration (g's)

0


0.3

Acceleration (g's)

-0.6

+

0.6 6

20

Acceleration (g's)

4

18

Acceleration (g's)

0

16

Acceleration (g's)

0.3

2

-0.3

14


Acceleration (g's)

+

0


Acceleration (g's)

-0.6

0.6 6

Acceleration (g's)

4

Acceleration (g's)

0

Acceleration (g's)

0.3

2

-0.3

Acceleration (g's)

0

Acceleration (g's)

-0.6

Acceleration (g's)

-0.3

+

=

0.6

Acceleration (g's)

0

Acceleration (g's)

+

Acceleration (g's)

0.6

6

14


-0.3

16

18

20

=

1989 Loma Prieta - Corralitos (128 deg.) 14

16

18

20

-0.6 0

2

4

6


14

16

18

=

20


Notional Collapse Fragility 4 36 records

3.5

Sag.m. (T=1.0s)[g]

3 2.5 2 1.5 1 0.5 0 0

0.05

0.1


0.15


Notional Collapse Fragility • Order collapse data from least to greatest • Plot as a cumulative distribution function Probability versus collapse intensity 4 3.5

Sa g.m. (T=1.0s)[g]

3 2.5 2 1.5 1 0.5 0 0

0.05

0.1

0.15



Notional Collapse Fragility Curve 1.0

Collapse Probability .

0.9

Comprehensive Collapse Data Lognormal Distribution

0.8 0.7 0.6 0.5

50% probability of collapse at SCT = 1.6g

CMR

Collapse Margin Ratio CMR = 1.6g / 0.9g

0.4 0.3 0.2 0.1

10% probability of collapse at SCT = 0.9g (SMT)

Acceptably low probability of collapse given MCE spectral acceleration

0.0 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) ATC-63 Quantification of Building System Performance and Response Parameters

Performance 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 Example


Example – RC SMF System Develop Test Data

Develop Design Rules

Define Archetypes Develop Archetype Models Analyze Archetype Models Evaluate System Performance No

P[Collapse] < Limit

Reinforced Concrete Special Moment Frame System

Yes

Review and Documentation ATC-63 Quantification of Building System Performance and Response Parameters

System Conception Typical Frame Members Beams: 32” to 40” deep Columns: 24”x28” to 30”x40” Governing Design Parameters

8 inch PT slab

- Beams: minimum strength - Column size: joint strength - Column strength: SCWB - Drift: just meets limit •

Office occupancy

•

Frame System

•

High seismic regions

•

Design Code: IBC / ACI / ASCE 7


27

System Configuration Space Frame

Perimeter Frame

Bay Width (e.g., 20 or 30 feet) ATC-63 Quantification of Building System Performance and Response Parameters

System Design Space 20-story

Number of Stories 12-story

Story Height

8-story

4-story 2-story 1-story

13' (typ.) 15'

3 bays @ 20'

3 bays @ 20'

3 bays @ 20'

3 bays @ 20'

3 bays @ 20'

3 bays @ 20'


Performance Groups 20-foot bays

Space frame

High seismic design

Performance Group Summary Grouping Criteria Group No.

Basic Configuration

Design Load Level Gravity

PG-1

Max SDC

PG-2

High

PG-3 PG-4 PG-5 PG-6 PG-7 PG-8

Seismic

Min SDC Type 1 Max SDC Low Min SDC

Period Domain

Number of Archetypes

Short

≥3

Long

≥3

Short

≥3

Long

≥3

Short

≥3

Long

≥3

Short

≥3

Long

≥3

Repeat for 30-foot bays Perimeter frame Low seismic design ATC-63 Quantification of Building System Performance and Response Parameters

Deterioration Modes and Collapse Scenarios

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 ATC-63 Quantification of Building System Performance and Response Parameters

Deterioration Modes

A Flexural hinging of

B Column compressive C Beam-column shear

beam-column elements

failure

failure

D

E Pull-out and bond-

F Slab-column

slip of rebar at connections

connection punching shear

Joint shear failure


Nonlinear Analysis Models Joints with both bond-slip springs and shear springs Column bondslip springs

Lumped plasticity beam-columns

2D multistory model to capture likely sidesway collapse scenarios and component behavior ATC-63 Quantification of Building System Performance and Response Parameters

Concrete Hinge Model Calibration Identify and Test Key Parameters: • strength • initial stiffness • post-yield stiffness • plastic rotation (capping) capacity • post-capping slope • cyclic deterioration rate

Example Data Set:

300

Shear Force (kN)

200

Experimental Results Model Prediction

• 250+ columns (PEER database) • flexure & flexure-shear dominant • calibrated to median (characteristic) values

100

0 -100 -200

-300 -0.1

-0.05

0

0.05

0.1

Column Drift (displacement/height)


Simulation Results 4 36 records 3.5

Sag.m. (T=1.0s)[g]

3

2.5 2 1.5 1 0.5 0 0

0.05

0.1


0.15


Simulation Results: Collapse Modes

4

40% of collapses

3.5

27% of collapses

Sa g.m . (T = 1.0s )[g]

3

2.5

2

1.5

1

17% of collapses

12% of collapses

**Predicted by Static Pushover

0.5

0 0

0.05

0.1

0.15


Incremental Dynamic Analysis 5% of collapses

2% of collapses


Simulation Results: Collapse Data 4

3.5

Capacity Stats.: Median = 2.2g σLN = 0.36

2.5

Mediancol = 2.2g

2

Sa

g.m.

(T=1.0s)[g]

3

1.5

1

MCE = 0.8 g 0.5

0 0 0.05 0.1 0.15 Maximum Interstory Drift Ratio ATC-63 Quantification of Building System Performance and Response Parameters

Effect of Uncertainties FOUR CONTRIBUTORS: 1. Record-to-Record Variability (βRTR = 0.4) 2. Design Requirements

1 0.9 0.8

= 0.4

0.7

> 0.4

0.6 0.5 0.4 0.3

3. Quality of Test Data 4. Quality of Analytical Model

0.2 0.1

CMR

0 0

1

2

3

4

Sa/SMT

2 2 2 2 + β DR + βTD + β MDL βTOT = β RTR

Collapse Probability at MCE?

Greater uncertainties will require larger median collapse margins ATC-63 Quantification of Building System Performance and Response Parameters to satisfy maximum collapse probability at MCE

5

Quality Ratings Table 3-1 Quality Rating for Design Requirements Completeness and Robustness High. Extensive safeguards against poor behavior. All important design and quality assurance issues are addressed.

Confidence in Basis of Design Requirements High

(A) Superior

Medium

Low

(B) Good

(C) Fair

M edium. 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

--


Total Collapse Uncertainty • Design Requirements: • Test Data: • Nonlinear Model:

A-Superior B-Good A-Superior

Uncertainty - Nonlinear Model

A - Superior

Uncertainty - Quality of Uncertainty - Quality of Design Requirements 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


Adjusted Collapse Fragility Curve 1 0.9

3.5

Sa g.m . (T = 1.0s )[g]

3

2.5

2

1.5

1

0.5

0 0

0.05

0.1


Incremental Dynamic Analysis Results

0.15

Cummulative Probability of Collapse

4

0.8

CMR = ??

0.7 0.6 0.5

Median = 2.2g

0.4

σLN, Total = 0.36

0.3 0.2

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

0.1 0 0

0.5

1

1.5

2

Sa

2.5 g.m.

3

3.5

4

(T=1.0s) [g]

MCE = 0.8g


4.5

5

Acceptable Collapse Margin Ratios Total System Collapse Uncertainty

Collapse Probability 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

On average per performance group

For any one archetype


Example Results – RC SMF System Design Configuration Arch. Design ID No. of Framing / Seismic Static Ω Number Stories Gravity SDC Loads 2069 2064 1003 1011 1013 1020

Computed Collapse Margin CMR

µc

SSF

ACMR

Acceptance Check Accept. ACMR

Pass/Fail

Maximum Seismic (Dmax) and Low Gravity (Perimeter Frame) Designs, 20' Bay Width 1 P Dmax 1.6 1.18 16.1 1.34 1.58 1.59 Near Pass 2 P Dmax 1.8 1.50 19.5 1.34 2.01 1.59 Pass 4 P Dmax 1.6 1.61 9.2 1.42 2.29 1.59 Pass 8 P Dmax 1.6 1.25 7.9 1.62 2.02 1.59 Pass 12 P Dmax 1.7 1.45 10.0 1.62 2.35 1.59 Pass 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 1001 1008 1012 1014 1021

1 2 4 8 12 20

Mean/Acceptable:

S S S S S S

Dmax Dmax Dmax Dmax Dmax Dmax

4.0 3.5 2.7 2.3 2.1 2.0

1.96 2.06 1.78 1.63 1.59 1.98

--

--

2.8

--

16.1 14.3 9.6 6.2 5.8 9.1

1.34 1.34 1.42 1.55 1.53 1.62

2.62 2.76 2.53 2.52 2.44 3.21

1.59 1.59 1.59 1.59 1.59 1.59

Pass Pass Pass Pass Pass Pass

--

2.68

2.02

Pass


RC SMF Example - Conclusions • A value of R=8 provides an acceptable level of collapse safety • The Methodology is reasonably wellcalibrated 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 Considerations • Implementation involves: Uncertainty Judgment Potential for variation

• Peer Review is critical for: Testing Archetype development Analytical modeling Quality rating assessment

Ground Motions

Analysis Methods

Methodology

Test Data

Design Information

Requirements

Requirements

Peer Review Requirements


Observations and Findings


Observations 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…


Observations and Findings • 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 ATC-63 Quantification of Building System Performance and Response Parameters

Summary • 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 (App. F)

• FEMA P-695 is now available online and in print ATC-63 Quantification of Building System Performance and Response Parameters

Thank you!


Heintz ATC 63

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