基于概率性地震需求模型的桥梁易损性分析

采用概率性地震需求分析方法，建立了汶川地区典型简支梁桥的分析型地震易损性模型。基于汶川地震桥梁震后调查资料，评估了桥梁结构参数的不确定性，抽样并生成一系列桥梁的有限元模型样本。利用汶川地震实测地震波对所建立的桥梁有限元模型进行非线性动力时程分析，并记录每一组分析中桥梁构件的地震峰值响应，通过回归分析建立地震动强度和桥梁构件地震需求之间的关系。在确定桥梁不同损伤状态对应的构件极限状态后，基于对数正态分布假设生成不同损伤状态对应的地震易损性曲线，最后基于可靠度理论计算得到桥梁系统易损性的上下确界。生成的地震易损性曲线可以进一步用于地震风险评估和震后加固优先级决策。

Bridge Vulnerability Analysis Based on Probabilistic Seismic Demand Models

Analytical seismic vulnerability model of typically simply supported girder bridge was developed using the probabilistic seismic demand analysis approach. Based on collected data of damaged bridges from the 2008 Wenchuan Earthquake, a set of finite element model samples of bridges were produced by considering uncertainties with bridge parameters. Nonlinear dynamic transient analysis was preformed using the Wenchuan Earthquake ground motions, in which seismic peak responses of bridge components were recorded. By using the regression analysis method, a relationship between the ground motion intensity and components seismic demand is established. Once the limit states of bridge components at each bridge damage state were determined, seismic fragility curves were generated based on the logarithmic normal distribution assumption. Finally, by adopting the reliability theory and calculation, the lower and upper bounds of bridge system vulnerability were obtained. The generated seismic fragility curves can be used for seismic risk assessment and bridge retrofit prioritization.