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Report - PEER - University of California, Berkeley

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Step (i)Step (ii)RepairoptionsStiffnessStrengthResponseDatabaseMean and standard deviation <strong>of</strong>maximum responsesDuctility Limit States Instant Derivation <strong>of</strong>Vulnerability FunctionsStep (iii)Figure 1. Overall procedure <strong>of</strong> the parameterized vulnerability function.It is noteworthy that response estimation (Step (ii)) can be performed withoutconsidering the effect <strong>of</strong> ductility supply. This is due to the fact that once the yieldpoint is determined by stiffness and strength ultimate displacement capacity does notaffect the shape <strong>of</strong> the capacity curve which, in this study, determines the response <strong>of</strong>a structure. The effect <strong>of</strong> ductility is implemented in determining the limit states(L.S.) to derive vulnerability functions. If the limit states are determined bydisplacement or displacement based damage index, it is very easy to determine limitstates according to the ductility variation. Otherwise, the relationship betweenductility and limit states needs to be defined before deriving vulnerability functions.3. DEMAND ESTIMATION METHODOLOGYEMPLOYING RESPONSE DATABASESThe objective <strong>of</strong> this study is to provide a tool for the construction <strong>of</strong> vulnerabilityfunctions for a wide range <strong>of</strong> structures with known response parameters. In theproposed method, the vulnerability function is constructed using parameterizedstructural response characteristics (stiffness, strength and ductility) and the ResponseDatabase. Simulation is therefore no longer needed. The structural responseparameters are defined for the single-degree <strong>of</strong> freedom (SDOF) system that isequivalent to the complex structure. The response database is a collection <strong>of</strong> pre-rundynamic analysis results for a range <strong>of</strong> structural response parameters. The proposedmethodology has conceptual analogy with earthquake response spectra, because it (i)utilizes simplified structural models (SDOF system), (ii) obtains maximum value <strong>of</strong>response history and (iii) constructs curves which replace dynamic response historyanalyses.3.1 Structure <strong>of</strong> the Response DatabaseThe database is designed to store information <strong>of</strong> structural responses as statisticalparameters and its structure is represented in Fig. 2. The basic element <strong>of</strong> structuringthe database is the process <strong>of</strong> obtaining a set <strong>of</strong> mean and standard deviation <strong>of</strong>maximum responses and this is the first step <strong>of</strong> constructing the response database.187

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