Issues and Needs for Implementing Performance-based Approaches in Engineering Practice

Transcription

1 2003 PEER Annual Meeting Issues and Needs for Implementing Performance-based Approaches in Engineering Practice By: Ronald O. Hamburger, S.E. Consulting Engineers Boston / San Francisco / Washington DC

2 Discussion Topics Current State of Practice Procedure Problems ATC-58 Project Vision Needs

3 Issues & Needs for Implementing Performance-based Approaches in Engineering Practice Current State of Practice ATC-40 ASCE-31 FEMA-356

4 Current Process Step 1 Define Performance Objective Performance Objective = Ground Motion x% - 50 years + Performance Level Operational Immediate Occupancy Life Safety Collapse Prevention

5 Step 2 Perform Analysis D t Predict Response Parameters: Strength demand on elements Inelastic deformation or ductility demand on elements Interstory drift ratios

6 3- Evaluate Performance Lateral Force - V 0 D LS D CP Lateral Displacement - D Comparing individual element strength and deformation demands against tabulated acceptable values Acceptable values based on: Element type & detailing Element importance Performance Level

7 Current Practice - Benefits Relatively simple to implement Encourages engineers to think in nonlinear manner Identify damage/failure modes Evaluate significance Clear improvement over past linear, codebased approaches

8 Current State Problems Standard Performance Levels don t directly relate to consequences of interest to consumer Number of lives lost $ repair cost Days lost occupancy Operational Immediate Occupancy Life Safety Collapse Prevention 0% Damage or Loss 99% none Time out of service permanent

9 Current State - Problems Performance evaluation is based on element behavior, not global behavior Much of the acceptance criteria is based on judgment rather than data Reliability of guidelines is unknown Potential liability problems associated with owner perception of performance warranty Guidelines appear to produce designs that are quite conservative compared with traditional practice

10 ATC-58 Project Develop a next-generation of performancebased seismic design guidelines Applicable to: Design of new buildings Upgrade of existing buildings Compatible with parallel efforts in: Blast Engineering Fire Engineering

11 ATC-58 Project Tasks Performance communication lexicon that is meaningful to stakeholders Building performance prediction engine Using performance communication lexicon Design performance levels and objectives Using performance communication lexicon Practical design procedures Comparison with current prescriptive approaches New prescriptive procedures

12 ATC-58 Limitations No Basic Research Draw upon and incorporate latest research performed by others Reach engineering consensus as to suitability and appropriate application of available technologies Develop practical guidelines for use in engineering applications

13 Project Work Plan PMP PBSD Guidelines SPP/NPP RMP Stakeholder Guide Federal Emergency Management Agency FEMA-349 Action Plan: Performance-based Seismic Design YEAR 1 YEAR 2 YEAR 3 YEAR 4 YEAR 5 YEAR 6 YEAR 7 YEAR 8 YEAR Team Development 1.1: Plan and administer PBSD program 1.4: Establish & implement education/outreach program 1.2, 1.3, 1.5: Set goals and meet with stakeholders, assess project progress, define responsibilities 5.1: Guidelines Format 5.1, 5.3, 5.6: Guideline outline, Verification, 25% 5.2, 5.3, 5.5, 5.6: Provisions, Nonstruct. QA, Verification, 50% 5.2, 5.3, 5.4, 5.6: Provisions, QA procedures, Verification, 75% Formal stakeholder review process 2.1, 2.2, 2.5: State of the art, Characterize performance, Interim Post EQ program 2.1, 2.2, 2.3, 2.6: Quantify performance and, hazard, Report 2.2, 2.3, 2.4, 2.6: Quantify performance and hazard ID uncertainties, Report 2.2, 2.3, 2.4, 2.6: Design and analysis methods, Reliability tools, Report 2.2, 2.3, 2.4, 2.6: Design and analysis methods, Reliability tools, Report 3.1, 3.2, 3.4: State of the art, Characterize performance, Report 3.1, 3.2, 3.4: Quantify performance, Report 3.2, 3.4: Quantify performance, Testing protocols Report 3.2, 3.3, 3.4: Design and analysis methods, Testing protocols, define responsibilities Report 3.2, 3.3, 3.4: Design and analysis methods, Testing protocols, define responsibilities Report 4.1: 4.5 ID and Quanitfy performance objectives, Report 4.1, 4.2, 4.4, 4.3: 4.5 Quanitfy loss, Develop financial tools, ID legal issues,report 4.2, 4.4, 4.3: 4.5 Develop financial tools, Educate, Report Formal stakeholder review process 6.1: Guide content 6.2, 6.6: Financial tools, Verification, 25% 6.2, 6.5, 6.6: Financial tools, PO maintenance, Verification, 50% 6.3, 6.4, 6.6: Examples,Design & construction process, Verification, 75% Operational Immediate Occupancy Life Safety Collapse Prevention YEAR , 5.6, 5.7: Verification, Revision process 100% 2.5: Final post-eq assessment program 3.3, 3.4: Post-eq assessment and innovative design 6.6, 6.7: Revision process 100% $20-27 Million 10 year Development Schedule

14 ATC-58 Products Performance Evaluation Method Guidelines for Performance Design Prescriptive Criteria for Design

15 ATC-58 Products Many types of stakeholders Developers Corporate Tenants Insurers Lenders Institutions Public Agencies Building Regulators

16 Building Performance Engine Annual Probability of Exceedance Hazard Function for Earthquake Intensity Foundation Earthquake Intensity Measure MMI pga S a (T 1 ) Sa{T 1, T 2 } Sa{T 1, T 2 }, Duration Run Analysis t Annual Probability of Exceedance Hazard Function for Earthquake Intensity Measure In Structure Earthquake Intensity Measure Engineering Demand Parameters Interstory Drift Plastic Rotation Element Force Cumulative Energy

17 Building Performance Engine Damage Function Engineering Demand Parameters EDP 0 D LS D CP Structural Performance Fragility Functions for Damage States Fragility for Damage State Y Fragility for Collapse Probability of Failure Engineeringi Demand Parameter Probability of Failure Engineeringi Demand Parameter

18 Building Performance Engine Fragility Functions for Damage States Fragility for Damage State Y Fragility for Collapse Probability of Failure Engineeringi Demand Parameter Probability of Failure Engineeringi Demand Parameter Loss Function Probability of Loss Exceedance Given Damage State - 100% 80% 60% 40% 20% 0% $1 $100 $10,000 $1,000,000 Loss - $1,000 Incipient Damage Damage State 2 Damage State 3 Damage State 4 Damage State 5

19 Building Performance Engine Annual Probability of Exceedance Hazard Function for Earthquake Intensity Measure In Structure Earthquake Intensity Measure Loss Function Fragility Probability of Loss Exceedance Given Damage State - 100% 80% 60% 40% 20% 0% $1 $100 $10,000 $1,000,000 Loss - $1,000 Incipient Damage Damage State 2 Damage State 3 Damage State 4 Damage State 5 Fragility for DamageLoss of Function Fragility for Overtrurning Probability of Failure Engineeringi Demand Parameter Probability of Failure Engineeringi Demand Parameter

20 Loss Functions Probability of Loss Exceedance Given Damage State - 100% 80% 60% 40% 20% 0% $1 $100 $10,000 $1,000,000 Loss - $1,000 Incipient Damage Damage State 2 Damage State 3 Damage State 4 Damage State 5 Average annual loss Probability of exceeding loss of given amount Probable loss given scenario event Maximum probable loss Maximum forseeable loss

21 Needs Intensity Measures Annual Probability of Exceedance Hazard Function for Earthquake Intensity Foundation Earthquake Intensity Measure MMI pga S a (T 1 ) Sa{T 1, T 2 } Sa{T 1, T 2 }, Duration Identification of most suitable intensity measures Different for different types of structures? Different for nonstructural components? Methods of developing hazard functions for intensity measures Quantification of uncertainties

22 Needs Analysis Procedures & Modeling Guidelines t Analytical methods that: Are reliable: unbiased low variability Consider soil-foundationstructure-component system Are practical: Can be implemented in design office

23 Needs- Damage Functions EDP Damage Function 0 D LS D CP Structural Performance Optimal demand parameters for characterizing damage: Different structural elements Global structural systems Acceptance criteria Values of demand parameters that indicate different levels of damage

24 Needs - Fragilities Probability of Failure Fragility for Overtrurning Engineeringi Demand Parameter Procedures to convert structural analysis into structural fragilities Standardized fragilities for nonstructural components and systems

25 Needs- Loss Functions Procedures for converting from damage to loss Probability of Loss Exceedance Given Damage State - 100% 80% 60% 40% 20% 0% $1 $100 $10,000 $1,000,000 Loss - $1,000 Incipient Damage Damage State 2 Damage State 3 Damage State 4 Damage State 5 Standardized loss functions for various structural and nonstructural systems and damage states

26 Needs Engineering Office Simple procedures Straight forward explanation of process Software to aid implementation of procedures