System seismic fragility analysis methods for bridge structures
WU Wenpeng1,2,3, LI Lifeng2
1.College of Civil Engineering and Mechanics, Xiangtan University, Xiangtan 411105, China;-
2.College of Civil Engineering, Hunan University, Changsha 410082, China;
3. Key Laboratory of Dynamics and Reliability of Structures, College of Hunan Province,Xiangtan University, Xiangtan 411105, China
A bridge is a structural system consisting of various interrelated and interacting components, and any component’s damage under earthquake affects the bridge’s functional integrity.Adopting a single component fragility to express the bridge’s system fragility may over-estimate the bridge’s aseismic capacity.A multi-span RC continuous girder bridge was taken as an example, and its finite element model was constructed with the software OpenSEES to conduct a great number of nonlinear time-history analyses.Simultaneously considering seismic damages of bridge pier, lead core rubber bearing, plate-type rubber bearing and bridge abutment, the bound estimation method, Monte-Carlo simulation one and the product of conditional marginal (PCM) one were applied to establish the bridge’s system seismic fragility curves.These fragility curves were contrastively analyzed to judge the applicability and reasonability of the three methods.The results showed that the traditional bound estimation method and the PCM one depend on component fragility analysis results, while Monte-Carlo simulation method is able to directly construct the bridge’s system fragility curve and to independently consider effects of various uncertainties; the PCM method can be used to quickly construct the bridge’s accurate system fragility curve, and it is more applicable for the bridge system fragility analysis considering multiple failure modes.
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