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Report - PEER - University of California, Berkeley

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structure remains elastic. This is equivalent to having no significant intersect betweenthe probabilistic response surface and the structural limit states in Figure 5a.However, such intersect exists in the limit space for the non-structural components,and the magnitude <strong>of</strong> this intersect (i.e., probability <strong>of</strong> exceeding the limit space) canbe calculated, and is expected to increase as a function <strong>of</strong> the earthquake returnperiod. Figure 6c expresses the resulting probability <strong>of</strong> exceeding the limit space as afunction <strong>of</strong> the earthquake hazard (itself expressed in probability <strong>of</strong> exceedence over50 years, in a manner compatible with code documents — 50%, 10% (500 yearsreturn period), and 2% probability <strong>of</strong> exceedence.. The probable non-structural loss,P NSL , can be expressed by the product <strong>of</strong> the probability <strong>of</strong> exceeding the limit state,P LS , and <strong>of</strong> the value <strong>of</strong> the non-structural investment, NS INV . For the probableexceedence <strong>of</strong> the limit space shown in Figure 6c for a design level corresponding toa 500-year return period, Figure 6b shows the resulting non-structural resiliencecurve, with the probable non-structural losses at time t o . The time at full recovery topre-earthquake conditions, t 1 , is entirely related to repair <strong>of</strong> non-structural damage.Quantification <strong>of</strong> the seismic resilience curve for the case <strong>of</strong> non-linear inelasticstructural response differ from the previous case by the presence <strong>of</strong> a structural loss(i.e., a drop in the value <strong>of</strong> structural investment due to damage) measurable from thefragility concept since there is now a quantifiable intersect between the probabilisticresponse surface and the structural limit states in Figure 5b. Figure 7b expresses theresulting probability <strong>of</strong> exceeding the limit space, P LS , as a function <strong>of</strong> the earthquakehazard, and Figure 7a the corresponding probable loss in the structural investment,P LS . If another earthquake was to occur at time t o + , the probability <strong>of</strong> exceeding thelimit state would be significantly greater (as shown in Figure 7b), and a further loss inthe structural investment (possibly to collapse) would occur.N INVNS INVStructuralInvestmentP SL = 0Probable Structural LossP SL = P LS x N INVNon-StructuralInvestmentP NSLProbable Non-Structural LossP NSL = P LS x NS INVt 0t 1Timet 0t 1TimeP LSP LS50% in50 Years10% in50 Years2% in50 YearsHazardFigure 6. Probable non-structural loss in case <strong>of</strong> linear-elastic structuralresponse.167

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