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Report - PEER - University of California, Berkeley

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Nonlinear time history analyses are performed using the same 32 ground motions andfragility curves are generated with the resulting 256 (8 floors x 32) motions. Benchamplification is accounted for, considering representative values <strong>of</strong> f = 10Hz andnζn= 10%. Figure 5(a) and (b) show a comparison <strong>of</strong> the fragility curves for a meansliding displacement <strong>of</strong> 5 cm, considering the three different buildings. It may beobserved from these curves that for a damage measure <strong>of</strong> 5 cm mean sliding, themedian values and the log-standard deviations <strong>of</strong> the lognormally distributed fragilitycurves are smaller for the steel buildings, than that <strong>of</strong> the RC building. This impliesthat given a particular value <strong>of</strong> the PHFA, sliding distances are more for longer periodstructures. This can be attributed to the motion amplification at the floor levels for thecomparatively flexible steel buildings. From these analyses, the mean absoluteacceleration amplification was 1.52, 2.19 and 1.00 for Steel-1, Steel-2, and RC, withassociated cov values <strong>of</strong> 0.35, 0.39, and 0.21, respectively.Ro<strong>of</strong>8 Story Flexible Frame8 Story Rigid Frame32.415.64 6.225@4.116.02 5.89 6.0231.854.52Level 6Level 5Level 4Level 3Level 2Level 1W14x74 W14x48 W14x38 W14x30W14x109 W14x82 W14x68 W14x53(a) RC (b) Steel-1 (c) Steel-2Figure 4. Building models used in this study: (a) transverse bay <strong>of</strong> a seven-storyreinforced concrete building, modeled by Lee and Mosalam (2002) (RC), (b) and(c) two eight-story steel moment frame buildings (Steel-1 and Steel-2). (units inmeters).Probability <strong>of</strong> exceedence1.00.80.60.40.2(a)φ = 0.5, RCφ = 0.9, RCφ = 0.5, Steel-1φ = 0.9, Steel-1φ = 0.5, Steel-2φ = 0.9, Steel-20.00.0 0.5 1.0 1.5 2.0 2.5Peak horizontal floor acceleration (g)Probability <strong>of</strong> exceedence1.00.80.60.40.2W21x44W21x50W21x57W21x68(b)5.49m 25.62mW14x68W14x176 W14x120 W14x74W14x109W14x233 W14x193 W14x120W27x84W27x84W27x102W27x1140.00.0 0.5 1.0 1.5 2.0 2.5Peak horizontal floor acceleration (g)25.62m5.49mφ = 0.5, RCφ = 0.9, RCφ = 0.5, Steel-1φ = 0.9, Steel-1φ = 0.5, Steel-2φ = 0.9, Steel-2Figure 5. Effect <strong>of</strong> different building types on fragility curves for DM = 5cmand: (a) µ = 0.3 and (b)sµ = 0.7. (s f n= 10Hz and ζ = 10%).n4.3 Development <strong>of</strong> Generalized Fragility CurvesAlthough fragility curves may be developed on a per-equipment basis, generalizedcurves, with broader applicability to categories <strong>of</strong> equipment, and considering a range205

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