COSMOS Annual Meeting. ATC-63 Quantification of Building System Performance and Response Parameters

Transcription

1 COSMOS Annual Meeting ATC-63 Project Quantification of Building System Performance and Response Parameters Charlie Kircher Kircher & Associates Curt Haselton Professor, CSU-ChicoChico November 9, 2007

2 Overview Presentation Topics Background and Project Statust Methodology Key Concepts Ground Motions Objectives and Selection Criteria Record Sets (Far-Field and Near-Field) Scaling of Records Spectral Shape Adjustment

3 ATC-63 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 of buildings having different structural systems (i.e., different lateral-force- resisting systems) Secondary Evaluate Level a Playing sufficient number Field 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) i that t would more reliably achieve the inherent earthquake safety performance objectives of building codes

4 TOP Management Chris Rojahn (PED) Jon Heintz (PTM) William Holmes (PQC) PMC Members Charles Kircher (Chair) Greg Deierlein Stanford M. Constantinou Buffalo John Hooper - MKA James Harris HA Allan Porush - URS Project Organization Project Review Panel Twelve Members FEMA Applied Technology Council TOP Management Committee Project Executive Director (Chair) Project Technical Monitor Project Quality Control Monitor ATC-63 Project Management Committee Project Technical Director (Chair) Five Members FEMA Michael Mahoney Robert Hanson (Adv.) PRP Members Phipps (Chair) Elnashai - MAE Ghosh - SKGA Gilsanz- GMS Hamburger - SGH Hayes - NIST Holmes R&C Klingner - UT Line - AFPA Manley - AISI Reinhorn - UB Rojahn - ATC Sabelli - DASSE Working Groups Technical Consultants Working Groups Stanford NDA Krawinkler AAC SUNY NSA/NCA Filiatrault Wood ATC Staff Technical Support Administration

5 Project Tasks and Schedule MONTHS Task 1: Development of Project Work Plan Task 2: Project Management and Oversight Task 3: Review Relevant Research- Task 4: Development of a Recommended Seismic Performance Factor Methodology Task 5: Conduct Benchmark Evaluations of Recommended Seismic Performance Factor Methodology Task 6: Sample Evaluation of Selected Structural Systems (Verification Process) Task 7: Development of a Draft Guidance Document Task 8: Plan and Conduct Workshop (Year 3) Task 9: Preparation of Project Report and Related Outreach Materials (Year 3) ATC-63 PMC Meetings: X X X X X X ATC-63 PRP Meetings Y Y : Task milestone/completion

6 Seismic-Force Force-Resisting Systems (Tasks 5 and 6) Reinforced-Concrete Structures 4-Story SMF, IMF and OMF 12-Story IMF/OMF and Shear Wall (Core Wall) Parametric Study of RC Frames 1, 2, 4, 8, 12 and 20 stories Space vs. perimeter configurations Drift Limits (1% - 4%) Weak story irregularities (Code limits: 80%, 65%) Concrete Stanford Gregory Deierlein Curt Haselton Abbie Liel Brian Dean Jason Chou Ashpica Chhabra John Hooper (MKA) Brian Morgan (MKA)

7 Seismic-Force Force-Resisting Systems (Tasks 5 and 6) Wood Structures (CUREE): Townhouse Superior, typical, poor quality Apartment Superior, typical and poor quality Other (Japanese Home, Templeton Hospital) Autoclaved Aerated Concrete (AAC) Test Structures Steel Structures: 4-Story (RBS) SMF (IMF, OMF) Wood - Buffalo Andre Filiatrault Ioannis Christovasilis Assawin Wanitkorkul k Kelly Cobeen (C&A) Michael Constantino AAC - Stanford Helmut Krawinkler Farzin Zareian Kevin Haas Dimitiros Lignos Steel - Stanford Greg Deierlein Abbie Liel Helmut Krawinkler Dimitiros Lignos Curt Haselton

8 Seismic-Force Force-Resisting Systems (Special Studies) Low Seismic Structures Parametric Study RC OMF s 2, 4, 8 and 20 stories Space/perimeter configurations SDC B and SDC C designs Low Ductility Structures Steel SCBF systems Non-Conventional Structures Parametric Study Base Isolation Special Studies Stanford Gregory Deierlein Abbie Liel Steve Cranford Charlie Kircher (CKA) Curt Haselton (CSU) 4-Story RC SMF and RC OMF Superstructures Superstructure Strength (vary effective R I factor) Moat Wall Gap Size (1.0, 1.2 and 1.4 x minimum)

9 Draft Report (90%) Sections (Task 7) 1. Introduction Background and 2. Methodology Overview Material 3. Required System Information 4. Structure Archetypes 5. Models and Criteria for Collapse Assessment e Methodology 6. Nonlinear Analysis of Archetype Models Guidelines 7. Performance Evaluation 8. Administrative Requirements 9. Example Applications 10. Supporting Studies Supporting 11. Summary and Conclusions Material Appendices, Glossary, References

10 Scope and Basis of the Methodology New Buildings Methodology applies to the seismic-force-resisting 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 7-05), including site class effects

11 Elements of the Methodology Ground Motions Analysis Methods Methodology Test Data Requirements Design Information Requirements Peer Review Requirements

12 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) ASCE 7-05/NEHRP Design Provisions (e.g., base shear) V C s W Performance-Based Analysis Methods Probabilistic Collapse Fragility Nonlinear (Incremental) Dynamic Analysis

13 Lateral Se eismic Fo orce (Bas se Shear) Definition of Seismic Performance Factors (SPF s) (from FEMA 450 Commentary) V E V Y V Design Earthquake Ground Motions C d R Response Modification Coefficient V E /V C d Deflection Amplification Factor (δ/δ E )R Ω O Overstrength Factor V Y /V Ω 0 R Notional Pushover Curve δ E /R δ δ E Lateral Displacement (Roof Drift)

14 SPF s and MCE Collapse Margin Ratio ATC-63 Spectr ral Accele eration (g ) Ŝ CT S MT S Y C s CMR 1.5R MCE Ground Motions (ASCE 7-05) ) T Median Collapse Ground Motions CMR 1. 5R ŜS S S C 1.5C d CMR C d R Ω Ω S C Y C s CT MT MT s SD MT /1.5R Spectral Displacement SD MT ŜD CT

15 Notional Collapse Fragility One Data Point Building (Joe s Bar) Scaled Ground Motion Record Joe s Loma Prieta - Corralitos (128 deg.) Time (Seconds) Beer! Food! Acceleration (g's) Incipient Collapse Evaluation of a single structure (one configuration/set of performance properties) to failure using one ground motion record scaled to effect incipient collapse

16 Example NDA Results Collapse (1 archetype analysis model 1 ground motion record)

17 Notional Collapse Fragility Comprehensive Data Building Incipient (Joe s Building Bar) Collapse Incipient (Joe s Building Bar) Collapse Incipient (Joe s Building Bar) Ground Motion Collapse Incipient Loma Prieta - Corralitos (128 deg.) (Joe s 0 Joe s Building Bar) Ground Motion Collapse Incipient Loma Prieta - Corralitos (128 deg.) (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + Food! (Joe s A+ - 0 i Joe s Building Bar) Ground Motion Collapse Incipient Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Bar) Ground Motion Collapse 06 0 Incipient Joe s Building Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Joe s Building Bar) Ground Motion Collapse Incipient Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) + - Food! (Joe s Bar) Ground Motion Collapse Joe s Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + - Food! Ground Motion Joe s Beer! Time (Seconds) Loma Prieta - Corralitos (128 deg.) 03 + Ac+ - Food! Ground Motion Joe s Time (Seconds) Beer! Loma Prieta - Corralitos (128 deg.) + - Food! Joe s Time (Seconds) - Robust analytical Food! models of building configuration/performance properties evaluated with representative earthquake records Acceleration (g's) Acceleration (g's) Acceleration (g's) Acceleration (g's) cceleration (g's) Acceleration (g's) Acceleration (g's) Acceleration (g's) Acceleration (g's) Acceleration (g's) Accelera ation (g's) Acceleration (g's) Acceleration (g's) Acceleration (g's) Acceleration (g's) Beer! Food! Beer! Food! cceleration (g's) Acceleration (g g's) + Acceleration (g's) - Comprehensive collapse data Time (Seconds)

18 Notional Collapse Fragility Curve llapse Pro obability. Co Comprehensive Collapse Data Lognormal Distribution 50% probability of collapse at S CT 1.6g CMR Collapse Margin Ratio CMR 1.6g / 0.9g 10% probability Acceptably low of collapse at probability of S CT 0.9g (S MT ) collapse given MCE spectral acceleration Collapse Spectral Acceleration (g)

19 Comparison of Two Hypothetical Systems with Different Fragility Curves Same MCE Design Level (R factor) R 1 CMR 1 1.5R 2 CMR 2 Colla apse Prob bability Collapse Fragility System No. 2 Collapse Fragility System No. 1 C S S MT Ŝ CT,2 Spectral Acceleration (g) ŜCT,1

20 Sources of Collapse Uncertainty Calculated (Incremental Dynamic Analysis): Record-to-Record Variability, β RTR Other Sources (based on Quality Ratings): Design Requirements, β DR Test Data, β TD Nonlinear Analysis Models, β MDL Total Collapse Uncertainty, β TOT : β β + β + β + TOT 2 RTR 2 DR 2 TD β 2 MDL

21 Elements of the Methodology Ground Motions Analysis Methods Methodology Test Data Requirements Design Information Requirements Peer Review Requirements

22 ATC-63 Ground Motion Record Sets - Objectives Code (ASCE 7-05) Consistent Pairs of horizontal components selected and scaled from individual recorded events Section16131ofASCE events of 7-05 Very Strong Ground Motions Ground motions strong enough to collapse new buildings Large Number of Records Enough records in set to estimate median and RTR variability (collapse fragility) Structure-Type Independent Appropriate for NDA (IDA) of variety structures with different dynamic characteristics and performance properties Site/Hazard Independent Appropriate for evaluation of structures located at different sites/hazard levels

23 Record Source - PEER-NGA Database 3,551 records (

24 Record Selection Criteria Two Record Sets: Far-Field Record Set - R > 10 km Near-Field Record Set R < 10 km (w and w/o Pulses) 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 Record Quality - Lowest Useable Frequency < 0.25 Hz

25 Far-Field Field Ground Motion Record Set 22 records (2 components each): 14 Events (8 California, 6 Foreign) Fault Mechanisms and Site Conditions: 15 strike-slipslip faults, 7 thrust faults 16 Site Class D, 6 Site Class C Average Properties (Range of Properties) Magnitude: M7.0 (M6.5 M7.6) Fault Distance: 16.4 km (11.11 km 26.4 km) PGA: 0.43g (0.21g 0.82g) PGV: 46 cm/sec. (19 cm/sec. 115 cm/sec.)

26 Response Spectra and Dispersion of the Far-Field Field Record Set (Normalized) Spectr ral Accelera ation (g) Median Spectrum -- Far-Field Set 2 +1L LnStdDev Spectrum - FFS Set LnStdDev Spectrum - FF Set 1.6 Std Dev Ln(Sa) - Far-Field Set Period (seconds) Standard d Deviation - Ln (Sa)

27 Epsilon Far-Field Field Record Set ation (g) Spectr ral Acceler Epsilon - Median of Far-Field Record Set Period (seconds)

28 Near-Field Ground Motion Record Set 28 records (2 components each): 14 Events (6 California, 1 Alaska, 7 Foreign) 14 Records w/pulses, 14 records w/o pulses (Baker) Fault Mechanisms and Site Conditions: 14 strike-slip faults, 14 thrust/normal faults 11 Site Class D, 15 Site Class C, 2 Site Class B Average Properties (Range of Properties) Magnitude: M7.0 (M6.5 M7.9) Fault Distance: 4.2 km (1.7 km 8.8 km) PGA: 0g (0.22g 1.43g) PGV: 84 cm/sec. (30 cm/sec. 167 cm/sec.)

29 Comparison of Median Spectra Far-Field Field and Near-Field Record Sets Spectr ral Accelera ation (g) Median Spectrum - Near-Field Record Set Median Spectrum - Far-Field Field Record Set Spectra Ratio - Near-Field/Far-Field Near-Source Factors (Tables 16-S/16-T, 1997 UBC) Spectral Fault Distance Domain 2 km 5 km 10 km 15 km Accel Veocity Spectra Rat tio Period (seconds)

30 Comparison of Median Spectra Far-Field Field Set and Near-Field Pulse Subset Spectr ral Accelera ation (g) Median Spectrum - NF Pulse No Pulse Subset Subset Median M Spectrum S t - Far-Field F Field Record R dset S t Spectra Ratio - NF Pulse/Far-Field No Spectra Rat tio Period e (seconds)

31 Comparison of Median Spectra Far-Field Field Set and Near-Field Pulse-Fault Normal (FN) Subset Spectra ral Accelera ration (g) (g) NF Median Pulse Spectrum FN Subset - NF Pulse No Pulse Subset Subset Far-Field Median Fi ldr Spectrum SRecord t ds - Set Far-Field F Field Record R dset S t NF Spectra Pulse Ratio FP/Far-Field - NF Pulse/Far-Field No Period e (seconds) Spectra S Rat atio

32 Example Comparison of Collapse Results Far-Field Field and Near-Field Record Sets RC SMF Building Archetype Far-Field Baseline (SDC Dmax) Near-Field Designs Evaluated for SDC E Seismic Demand (MCE) Near-Field Record Set NF - Pulse FN Record Subset Height CMR CMR NF/FF (%) CMR NF/FF (%) 1-Story % 7 53% 4-Story % % 20-Story % % Far-Field building archetypes designed for SDC D seismic demands Near-Field building archetypes designed for SDC E seismic demands (i.e., SDC E seismic demand 1.2 x SDC D demand at short-periods and SDC E seismic demand 1.6 x SDC D demand at long periods) 20-Story archetype design governed by minimum base shear

33 Scaling of Records ASCE Scaling of records consistent with requirements of Section ASCE 7-05 (e.g., records scaled to match Code-defined defined MCE response acceleration) Two Elements: Normalization of Records. Individual Ground motion records are normalized by their peak respective ground velocity (PGV) Scaling of Record Set. Record set (of normalized records) collectively increased (or decreased) in intensity as required to determine median collapse Record Set Intensity. Based on spectral acceleration at the fundamental period, T,, of the archetype of interest as defined by Section of ASCE 7-05 T C u T a C u C t h x n 0.25

34 Normalization of Records Purpose - Remove unwarranted variability (due to differences in event magnitude, distance to source, source type and site conditions) without eliminating inherent aleatory record-to-record variability Approach - Normalize individual records of set by PGV Effect Comparison of As Recorded and Normalized Properties (Far-Field Record Set): Parameter Value PGA (g) PGV (cm/sec.) As-Recorded Normalized As-Recorded Normalized Maximum Minimum Max/Min Ratio Average

35 Example Scaling of Far-Field Field Record Set to Code MCE Seismic Demands at T 1-Second Spectra al Accelera ation (g) FF Median Scaled to MCE SDC D (max) Far-Field Record Set Median Spectrum FF Median Scaled to MCE SDC B (min) Period (seconds)

36 Spectral Shape Factors Some Background: Spectral shape (ε) dramatically affects collapse capacity Spectral shape (ε)is related dto the ground motion intensity level, with rare motions having a peaked spectral shape (Baker and Cornell) An MCE motion is a rare motion ATC-63 Approach: Record sets do not (can not) have the proper spectral shape (ε) records sets are essentially (ε) neutral To account for spectral shape (ε), simplified correction factors (spectral shape factors) are used to adjust median collapse capacity

37 Illustration of Spectral Shape and ε nt [g] Important for taller buildings sensitive to higher mode a componen effects. Sa Black set selected to have mean ε2.0 20at t1 1sec (20 records) Spectral shape (ε) more important for: Mean of Spectra for ε Neutral Set Mean of Spectra for ε 1.0 Set - highly ductile buildings. - buildings where collapse is sensitive to higher modes. Blue set selected without considering ε (26 records) Period [seconds] Buildings with high deformation capacity will have period elongation into this region. Ground motions selected by Baker

38 Expected ε Values at Site (from USGS) SDC ε 0 SDC B/C 1.00 SDC D 1.50 SDC E

39 ε Values of the ATC-63 Far-Field Field Record Set ords Mean of ε(t),reco Possible target ε (from last slide) Basic Far-Field Ground Motion Set (22x2 records) Simplified Trend How much does this difference in ε affect the median collapse capacity? Period (T) [sec]

40 This Much SSF Formula ˆ β1 μ c ( )( ) 3 ( ) β ε ε SSF exp β ( T ) ( T ) 1 o, records SDC ε 0 Mean of ε(t),records B/C 1.0 D 1.5 E Basic Far-Field Ground Motion Set (22x2 records) Simplified Trend Period (T) [sec]

41 Example Spectral Shape Factors SDC D

42 Collapse Fragility Illustration Median Collapse (2.0g) lapse Pro obability. Col Median Collapse (1.6g) of archetype determined from adjusted NDA using by Spectral scaled 0.7 Shape record Factor set (SSF 1.25) fragility increased 03 Collapse fragility based MCE to account on record-to-record for all sources 0.2 of variability (β TOT RTR ) 0.4) 0.1 Acceptably Low Collapse Probability Collapse Spectral Acceleration (g)