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Report - PEER - University of California, Berkeley

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Sample derivation <strong>of</strong> vulnerability functions corresponding to variousdisplacement limit states, for the same structures shown in Fig. 5 (elastic-perfectlyplastic,T=0.8 sec. and S.R.=0.1; 0.2;0.3), are presented in Fig. 7.Prob. (x > 20mm)Prob. (x > 60mm)10.80.60.40.2010.80.60.40.20S.R.= 0.1S.R.= 0.2S.R.= 0.30 0.1 0.2 0.3 0.4 0.5PGA (g)(a) L.S. = 20 mmS.R.= 0.1S.R.= 0.2S.R.= 0.30 0.1 0.2 0.3 0.4 0.5PGA (g)Prob. (x > 40mm)Prob. (x > 80mm)10.80.60.40.2010.80.60.40.20S.R.= 0.1S.R.= 0.2S.R.= 0.30 0.1 0.2 0.3 0.4 0.5PGA (g)(b) L.S. = 40 mmS.R.= 0.1S.R.= 0.2S.R.= 0.30 0.1 0.2 0.3 0.4 0.5PGA (g)(c) L.S. = 60 mm(d) L.S. = 80 mmFigure 7. Vulnerability functions for various limit states (L.S.).Sources <strong>of</strong> uncertainty can be categorized as (i) errors <strong>of</strong> ignorance andsimplification, (ii) measurement errors and (iii) statistical errors (Geysken et al.,1993). In each category, various uncertainties exist and their quantification iscomplex (Singhal and Kiremidjian 1998). The uncertainties can be implemented inthe derivation <strong>of</strong> vulnerability function as below:Prob (max. displ. > L.S.) = 1- Φ (ln( L.S.m) − λ)(5)2 22β + β + ⋅⋅⋅ + β1 2nwhere L.S. m is the median value <strong>of</strong> a displacement limit state and β i (i=1, 2, · · ·, n)represent various uncertainties. These can be demand uncertainty, capacityuncertainty and modeling uncertainty as in (Wen et al. 2004) or simply response andcapacity uncertainty (Dimova and Hirata 2000). Modeling <strong>of</strong> uncertainty is notpresented in this paper, though its importance in seismic loss assessment cannot beover-emphasized.193

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