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Report - PEER - University of California, Berkeley

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Expected Loss∫∫( Loss DS ) P( DS δ )= PVj j iP(δ ) d(DS)d(δ )(1)The average annual value <strong>of</strong> the loss can be obtained by realizing that theexpected loss calculated in equation (1) is actually the probable loss given that aspecific intensity <strong>of</strong> ground motion is experienced. Equation (1) can be used toevaluate the expected loss at each <strong>of</strong> a number <strong>of</strong> ground motion intensity levels, andthe average annual loss can be calculated as the sum <strong>of</strong> the expected loss at eachintensity level (EL k ) factored by the annual probability <strong>of</strong> experiencing each intensitylevel, and summing this over all possible intensity levels, or, in equation form:∫∫∫( Loss DS ) P( DS δ ) P( ( δ Sa ) P( Sa ) d(DS)d( ) d( Sa)Average Annual Loss = PVδ (2)jThe average annual loss can be summed, statistically, to provide the expectedloss over any desired interval <strong>of</strong> years. By calculating the combined uncertainty inthe losses associated with the hazard, response, damage and loss functions, it ispossible to estimate the expected losses at specified levels <strong>of</strong> confidence to produceother performance measures such as the popular Probable Maximum Loss (PML).3. SUMMARYWhen completed, the ATC-58 guidelines have the potential to revolutionize thepractice <strong>of</strong> performance-based design. They will introduce the practicing structuralengineer to the use <strong>of</strong> probabilistic structural reliability techniques and in the process,clarify the likelihood that performance-based designs will actually achieve intendedperformance. More important, they will enable the engineer to provide decisionmakers information that will be directly useful in selecting appropriate performancecriteria for building design and upgrade projects.REFERENCESAmerican Society <strong>of</strong> Civil Engineers (ASCE). 2002. Prestandard and Commentaryfor Seismic Rehabilitation <strong>of</strong> Buildings, <strong>Report</strong> No. FEMA-356, FederalEmergency Management Agency, Washington, D.C.Deierlein, G. G. 2004. “Overview <strong>of</strong> a Comprehensive Framework for EarthquakePerformance Assessment.” In Proceedings <strong>of</strong> the International Workshop onPerformance-Based Seismic Design, Bled, Slovenia, p.15.Earthquake Engineering Research Institute (EERI). 2000. Action Plan forPerformance-Based Seismic Design, <strong>Report</strong> No. FEMA-349, Federal EmergencyManagement Agency, Washington, D.C.Roeder, C. 2000. State <strong>of</strong> Art <strong>Report</strong> on Connection Performance, <strong>Report</strong> No. FEMA355D, Federal Emergency Management Agency, Washington, D.C.Structural Engineers Association <strong>of</strong> <strong>California</strong> (SEAOC). 1999. RecommendedLateral Force Requirements and Commentary, Appendix G, Performance-basedDesign, International Code Council, Whittier, CA, 1999.jiikk100

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