1. 1 Holmes IRCC Workshop October 18, 2006 Motivation and Development of PBEE for Existing and New Buildings William T. Holmes Structural Engineer Rutherford & Chekene

2. 2 Holmes IRCC Workshop October 18, 2006 Three areas of interest Retrofit of existing buildingsRetrofit of existing buildings Performance based codes (primarily new buildings)Performance based codes (primarily new buildings) Broad viewBroad view

3. 3 Holmes IRCC Workshop October 18, 2006 Performance Based Seismic Design: Why the emphasis in the last decade? The high cost of seismic retrofit, if done to comply with the prescriptive code requirements developed for design of new buildings, The high cost of seismic retrofit, if done to comply with the prescriptive code requirements developed for design of new buildings, -may be too high for economic feasibility -may not provide the performance intended Economic losses were higher than expected by owners due to both damage repair costs and business interruption in the Loma Prieta, and Northridge earthquakes (in this country).Economic losses were higher than expected by owners due to both damage repair costs and business interruption in the Loma Prieta, and Northridge earthquakes (in this country).

4. 4 Holmes IRCC Workshop October 18, 2006 FEMA 237: Issues Resolution Predecessor to FEMA 273 Phase 1 Project (1991-92) Identified major issues and recommended solutionsPhase 1 Project (1991-92) Identified major issues and recommended solutions On Performance Goals (Issue 11.2):On Performance Goals (Issue 11.2): -Incrementalize and prioritize strengthening activities to the greatest extent possible. Identify the performance expectation of each increment. -Specify requirements for Life Safety, which would form the core of the Guidelines Issues Identification and Resolution

5. 5 Holmes IRCC Workshop October 18, 2006 Building Performance Levels from FEMA 273 Operational Level Immediate Occupancy Level Life Safety Level Collapse Prevention Level Damage Control Range Limited Safety Range higher performance lower performance Code for new buildings 1-B 1-A 3-C 5-E

6. 6 Holmes IRCC Workshop October 18, 2006 Performance Objective Performance Level Hazard Characterization Performance Requirements Means of Verification Prescriptive Criteria Method (Improve current code) Traditional Performance Based Code Process Applied to Seismic Design Serve as an effective “Alternate Means” For Superior Performance For Equivalent Performance Introduction of Innovative Systems Alternate to Prescriptions

7. 7 Holmes IRCC Workshop October 18, 2006 Conclusions/Opinions Regarding Performance Based Codes Near term use of performance based design concepts in codes will be:Near term use of performance based design concepts in codes will be: -tuning the prescriptive provisions -enabling development of “standards” for acceptance of new systems -Providing method to determine equivalence for “alternate means” -facilitating designs “over code” (voluntary) Performance based design (at least using the detailed probabilistic methods, will not be the primary code method for a long time--if ever.Performance based design (at least using the detailed probabilistic methods, will not be the primary code method for a long time--if ever.

8. 8 Holmes IRCC Workshop October 18, 2006 A Broader View of Earthquake Engineering Design of New BuildingsDesign of New Buildings -Prescriptive “complete” method -Simplified methods Individual Existing BuildingsIndividual Existing Buildings -Evaluation -Retrofit -Determination of expected losses Groups of BuildingsGroups of Buildings -Risk analysis -Economic portfolio analysis -Regional loss studies Research and ReconnaissanceResearch and Reconnaissance

9. 9 Holmes IRCC Workshop October 18, 2006 Integration of all Uses Groups Of Buildings: Portfolio Analysis Regional Loss Studies Mitigation Studies Casualties Repair Costs Downtime Individual Buildings: Evaluation Retrofit Performance Objective Building Rating Systems: Probable Maximum Loss Other Percentage or Dollars

10. 10 Holmes IRCC Workshop October 18, 2006 Integration of all Uses Groups Of Buildings: Portfolio Analysis Regional Loss Studies Mitigation Studies Casualties Repair Costs Downtime Building Rating Systems: Probable Maximum Loss Other Percentage or Dollars Individual Buildings: Evaluation Retrofit Performance Objective

11. 11 Holmes IRCC Workshop October 18, 2006 Unified Performance System Groups Of Buildings: Portfolio Analysis Regional Loss Studies Mitigation Studies Casualties Repair Costs Downtime Building Rating Systems: Probable Maximum Loss Other Evaluation Retrofit Building Rating Portfolio Analysis Loss Studies Mitigation Studies Means of Verification

12. 12 Holmes IRCC Workshop October 18, 2006 Interest and Demand from Stakeholders Considering Broad Perspective

13. 13 Holmes IRCC Workshop October 18, 2006 Needed Extension of FEMA 356 Concepts for Broader View Base Shear Force Displacement Performance Level IOLSCP $, % replacement 0 25% 50% 100% Casualty rate 0.0 0.0001 0.001 0.01.25 Downtime, days 0 1 7 30 180 Elastic Limit Collapse

14. 14 Holmes IRCC Workshop October 18, 2006 Uncertainty is Big Issue

15. 15 Holmes IRCC Workshop October 18, 2006 Desirable Characteristics of the Verification Method Core of “Performance Engine” Ground Motion Structural Response Component and global damage level Losses: Casualties Cost of Repair Loss of use Consider uncertainty Extend over all ground motions P M Average Annual Loss Cost Benefit Analysis Death, Dollars, and Downtime