Report - PEER - University of California, Berkeley

analytical models generally have significant limitations due to simplicity of themodels, use of response spectra or other simple representations of ground shaking(Calvi 1999).Table 1. Comparison of vulnerability assessment methods (Lang 2002)MethodsEffortPrecision1 2 3 4 5observedvulnerabilityexpertopinionssimpleanalyticalmodelsscoreassignmentincreasing time and computation effortaccuracy of the assessmentdetailedanalysisprocedureApplicationbuilding stockindividualbuildingThe aim of the method proposed in this paper is to obtain precise assessmentresults closing up to those of the vulnerability assessment using detailed analysisprocedure with a very quick and simple procedure.2. OVERVIEW OF THE PROPOSED METHODOLOGYVulnerability functions may be derived analytically by simulation. Even for a limitednumber of random variables and for modest ranges of variation, the simulation effortis very considerable, reaching several hundreds of thousands of analyses. Every timethe structure is replaced or even modified, the repetition of the simulation is required.It is hereafter proposed to parameterize the problem in such a manner that a genericset of vulnerability functions will be derived. The parameters influencing the shape ofthe functions are related to (i) stiffness, closely related to serviceability limit state, (ii)strength, closely related to damage control limit states and (iii) ductility, closelyrelated to collapse prevention. By using the latter parameters with a response databasewhich is a collection of pre-run inelastic response analyses of structures with a widerange of response parameters, the vulnerability functions are directly obtained withoutthe need for simulation. This feature, allows consideration of various structuralconfigurations in the decision making of earthquake mitigation strategies, by reducingthe time and effort in the derivation of vulnerability functions.Fig. 1 represents the procedure to derive parameterized vulnerability functions. Inthe latter figure, the effect of a specific repair method on the vulnerability curve iscalculated through three main steps: (i) determination of response parameters afterrepair, (ii) response estimation using Response Database (RD) of which the detail ispresented in the following section and (iii) construction of vulnerability functionswith various limit states (L.S.).186