Report - PEER - University of California, Berkeley

OPEOPEOPEBaseShear000IO LS CP25% 50% 100%0.0001 0.001 0.01 0.251 7 30 180Figure 1. Schematic of PBEE assessment process and performance metrics.As with the introduction of any new technologies, there are limitations in thefirst-generation PBEE procedures that warrant further development. Among these arethe following: (1) Engineering demands and the calibrations between demands andcomponent performance are based on simplified analysis techniques, which are notamenable to the use of more realistic inelastic time-history simulation technologies;(2) Associations between engineering demands and component performance arebased somewhat inconsistently on relations between laboratory tests, analyticalmodels, and engineering judgment; (3) Relationships between building systemperformance and component limit states (e.g., definition of “Life Safety” performancebased on a single component deformation) are tenuous; and (4) Except for theprobabilistic definition of the seismic hazard, the methods are largely deterministicand do not rigorously account for the uncertainties in performance prediction.One of the key improvements of the PBEE approach under development byPEER is to provide a more explicit and transparent evaluation of system performancemetrics, that are more informative to stakeholders. Referring to the lower axes inFigure 1, these metrics provide quantitative measures of economic loss, life safetyrisks (casualties), and downtime. Metrics of this sort are common in regional seismicloss assessment. In this sense, the proposed framework will help unify detailedbuilding-specific engineering provisions with more empirically based regional lossassessment methods, such HAZUS (Kircher et al. 1997a,b).2. PERFORMANCE ASSESSMENT FRAMEWORKAs outlined in Table 1, the proposed assessment methodology is articulated by fourprocesses, which are roughly distinguished along disciplinary lines. Associated witheach process is an output variable, which provides for a systematic transfer ofinformation from one process to another. The assessment begins with definition of a16DeformationFEMA 273/356 Performance Levels$, % replacementCasualty rateDowntime, days