Due to wave passage effect, incoherence effect, local effect and other factors in seismic ground motion, the internal force and deformation of long span continuous rigid framed bridges will be error-estimated when seismic responses analysis is performed under identical support ground motion excitations. A Monte Carlo simulation method was used to establish the random sample for the system of large-span continuous rigid frame bridge under ground motion excitation, by means of considering the uncertainties of structural material and ground motion, both for identical support ground motion excitations and multiple support ground motion excitations. The ductility ratio of piers was defined as the index of damage state of the bridge. The seismic fragility analysis was carried out under the two different modes of excitations and the fragility curves of the bridge were given based on the damage state definition. The peak acceleration relationship between the two different modes of excitations was obtained under the same level damage.%针对地震动存在行波效应、场地效应、不相干效应等因素,分析大跨连续钢构桥在一致地震激励输入响应时结构内力和变形会被偏估问题,考虑结构及地震动不确定性,采用蒙特卡罗方法建立一致激励与多点激励两种工况下大跨连续钢构桥-地震动系统随机样本.以桥墩位移延性比表示桥梁破坏状态阶段,对桥梁易损性进行分析,给出大跨连续钢构桥结构的易损性曲线,得到同样程度破坏的多点地震激励与一致地震激励下加速度峰值关系.
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