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Report - PEER - University of California, Berkeley

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P(DM i|EDP i=IDR)1.00.8Gypsum-board partitions(a)P(DM i |EDP i =P FA)1.00.8Suspended ceilings(b)0.60.60.40.20.0DM1DM2DM30.00 0.01 0.02 0.03EDP [IDR]0.40.20.0DM1DM2DM30.0 1.0 2.0 3.0 4.0EDP [PFA (g)]Figure 4. Fragility functions <strong>of</strong> drift-sensitive and acceleration-sensitive nonstructuralcomponents at different damage measures; (a) gypsum-boardpartitions, (b) suspended ceilings.placements that lead to a dynamic instability in the structure. In the second approachit was assumed that the structure could collapse even if the lateral displacements werenot very large but enough to cause damage states that could trigger the loss <strong>of</strong> verticalcarrying capacity in structural members. The second type <strong>of</strong> collapse triggeringmechanism is particularly important in the case <strong>of</strong> non-ductile structures. In order toget an estimate <strong>of</strong> the probability <strong>of</strong> collapse due to the loss <strong>of</strong> vertical carryingcapacity <strong>of</strong> structural components it was assumed that if a loss <strong>of</strong> vertical carryingcapacity occurred in either a column <strong>of</strong> a slab column connection, such failure wouldtrigger a progressive collapse <strong>of</strong> the structure. As shown in Aslani and Miranda(2004b), with this assumption the probability <strong>of</strong> collapse due loss <strong>of</strong> vertical carryingcapacity (LVCC), P(C LVCC |IM), is equal to the largest probability <strong>of</strong> any individualstructural element that can loose its vertical carrying capacityP( C | IM ) = max [ P ( LVCC IM )]LVCC i |∀iwhere ( LVCC IM )P i | is the probability <strong>of</strong> losing the vertical carrying capacity in theith component conditioned on IM and is computed asP( LVCC | IM ) P( LVCC | EDP ) ⋅ dP( EDP IM )=∫ ∞ (9)|i i ii0where P ( LVCC i | EDP i ) is the probability <strong>of</strong> the ith component losing its verticalcarrying capacity given that it is subjected to a deformation level equal to edp.P ( LVCC i | EDP i ) is computed from fragility surfaces, developed for LVCC damagedP EDPi | IMstates on the basis <strong>of</strong> experimental studies on structural components. ( )is the probability density function <strong>of</strong> EDP i conditioned on IM, which can be estimatedfrom a probabilistic response analysis. Figure 5, presents a graphical presentation <strong>of</strong>the steps to estimate P(C LVCC |IM), using Eqs. (8) and (9).(8)156

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