摘要为研究考虑连续刚构桥(rigid-frame bridge ，RFB)不同施工阶段内力状态(internal force state ，IFS)对地震易损性的影响，以一座大跨高墩连续刚构桥为背景，基于等效荷载法提出了适用于连续刚构桥施工阶段的主梁和主墩的内力等效荷载计算公式，通过OpenSees建立了5个典型施工阶段考虑内力状态和不考虑内力状态的动力分析模型；选取40组典型的速度脉冲型近断层地震动记录为输入，采用增量动力分析法开展考虑施工过程与否的各典型施工阶段的动力时程分析，并以曲率延性系数为损伤指标，通过理论易损性方法得到了主墩墩底、墩顶和主梁根部的地震易损性曲线。结果表明：采用提出的内力等效荷载公式能较为准确地计算和模拟各典型施工阶段的等效内力状态；相同地震动强度下主墩墩底、墩顶和主梁根部在不同损伤状态下的损伤概率均随主梁悬臂长度的增加而增大；不考虑内力状态将低估墩底和墩顶的损伤概率，墩底沿纵桥向的损伤低估最为严重，且桥墩损伤概率的低估量随悬臂长度的增大而增大。
Abstract：To investigate the influence of internal force state (IFS) on seismic fragility of rigid-frame bridge (RFB) in different construction process, based on the equivalent load method, the formulas of equivalent internal force load of main girder and piers for RFB during typical construction stages were developed. Dynamic analysis models corresponding to five typical construction stages with and without IFS were simulated via OpenSees. Selecting 40 groups of near-fault ground motion records as input, the incremental dynamic analysis method was used to carry out the dynamic time history analysis of each typical construction stage considering the construction process or not. Taking curvature ductility as damage index, the seismic fragility of pier bottom, pier top and main girder root were obtained by theoretical fragility method. The results show that the formulas for equivalent internal force loads can be used to accurately calculate and simulate the IFS of the main bridge. The damage probability of the pier bottom, pier top and the main girder root under the same seismic level increases with the increase of the cantilever length in different damage states. Without considering the IFS, the damage probability of pier bottom and pier top will be underestimated, and the underestimation of pier bottom along the longitudinal direction is the most significant. The underestimation of the damage probability of piers will increase with the increase of cantilever length.
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