不同地震激励方向下隔震曲线梁桥易损性分析

为进一步评估隔震曲线梁桥在地震激励下的抗震性能，从地震易损性角度出发并兼顾考虑地震激励方向对其易损性的影响。利用APDL建立采用板式橡胶支座的隔震曲线梁桥有限元模型，从PEER中选取同一地震事件中的近断层地震动，按规范规定比例输入水平双向地震动进行非线性动力时程分析，结合地震响应与损伤指标计算得到各构件地震易损性曲线；考虑地震激励方向的变化，通过MATLAB编程绘制得到桥梁结构构件(桥墩与支座)以及整体系统的地震易损性曲面，分析探讨地震激励方向对隔震曲线梁桥易损性的影响。结果表明：不同极限状态下各桥墩切向损伤条件概率明显大于其径向，各支座的切向与径向易损性相差不大，但仍是各支座的切向易损性略大于径向易损性；桥梁各构件(桥墩与支座)切向易损性对地震激励方向均表现出很强依赖性，而径向易损性对其的依赖性相对较弱，且伴随损伤等级的提高，构件易损性对地震激励方向更加敏感；桥梁整体系统易损性对地震激励方向的变化不太敏感，且因各构件响应之间的相关性较高，其系统易损性更接近于易损性最大的构件——易损性下限；当进行隔震曲线梁桥抗震性能评估时，应考虑不同地震激励方向对其地震易损性的影响，从而使得易损性分析...

Fragility analysis of isolated curved girder bridges under different seismic excitation directions

To further evaluate the seismic performance of isolated curved girder bridges under seismic excitation, the influence of seismic excitation direction on their fragility was studied. A finite element model of an isolated curved girder bridge with laminated rubber bearings was established by APDL. Near-fault ground motions in the same seismic event were selected from PEER, and horizontal bidirectional ground motions were input according to the proportion specified in the code for nonlinear dynamic time-history analysis. The seismic fragility curves of the components were calculated by combining the seismic response and damage index. Considering the change in seismic excitation direction, seismic fragility surfaces of the components (pier and bearing) and bridge system were obtained using MATLAB programming and the influence of seismic excitation direction on the fragility of the isolated curved girder bridge was analyzed and discussed. The results show that under different limit states, the tangential damage probability of each pier is obviously greater than that in the radial direction. The tangential fragility of each bearing is slightly greater than the radial fragility, with little difference. The tangential fragility of bridge members (pier and bearing) strongly depends on the seismic excitation direction, whereas the dependence of radial fragility is weaker; with an increasing damage level, the fragility of members becomes more sensitive to the seismic excitation direction. The fragility of the bridge system, which is insensitive to changes in the seismic excitation direction, is closer to that of the most vulnerable component because of the high correlation between the responses of the components. When evaluating the seismic performance of the isolated curved girder bridges, the influence of the seismic excitation direction on their seismic fragility should be considered to make the fragility analysis results more reasonable and reflect their actual damage state more accurately.