DRAFT: US-JAPAN PBEE PAPER BY CORDOVA ... - PEER

6 @ 4m = 24mW530x92W610x101W610x101600 x700mm650 x750mmS a (g)432RCS PerimeterT1 = 1.50 secIV79-A6LP89-LGLP89-LXEZ92-EZNR94-NHNR94-RSNR94-SYKB95-JM2%in50yr12 @ 6.4m 9.6m35.2m2 @ 6.4mFigure 2 –Elevation of RCSperimeter frame.00.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0Period (sec)Figure 3 – Near FaultResponse Spectrum4. COLLAPSE ANALYSIS TECHNIQUESIncremented Dynamic AnalysisSeismic performance is assessed through nonlinear time history analyses using two sets ofground motions – one comprised of eight general records and another of eight near-fault recordswith forward directivity. Response spectra for the near-fault records are superimposed on the2% in 50-year design hazard spectrum used to design the case study buildings in Fig. 3.Acceleration components of the records are scaled, where the resulting ground motion intensityis reported in terms of either spectral acceleration, T ) , or the proposed new index,S a( 1aR SaαS .Shome and Cornell (1997) have demonstrated that such scaling of records will not bias theresults and is an appropriate technique for multi-level hazard analysis. More details on theground record properties and scaling issues for the records are summarized by Mehanny (2000).Results of the time history analyses are summarized by plotting the scaled intensity measureversus maximum Interstory Drift Ratio (IDR), creating what are referred to herein asIncremented Dynamic Analysis (IDA) curves. Shown in Fig. 4 are examples of the IDA curvesfor the RCS perimeter frame building subjected to the general records, where each data pointcorresponds to the peak IDR resulting from a single time history analysis. The collection of datapoints for a single ground record scaled to multiple hazard levels forms the IDA curve. Resultsare plotted in terms of the S aT ) intensity in Fig. 4a and( 1aR SaαS in Fig. 4b.7