大跨度连续梁拱桥多点多维地震响应分析

为研究多点多维地震动作用下大跨度连续梁拱桥的动力响应，以我国南方某主跨为139 m的钢管混凝土连续梁拱桥为研究对象，基于有限元软件OpenSEES建立桥梁的三维有限元分析模型，人工合成空间非一致地震动，探究地震动的失相干程度、场地条件及行波波速对桥梁动力响应的影响. 研究结果表明:地震波的空间变异性效应会对连续梁拱桥的地震响应产生明显影响，仅考虑一致地震动激励会高估桥梁结构的地震响应；场地效应对桥梁地震响应的影响规律最为突出，随着支撑点处的场地越来越松软，桥梁各个部位的内力及位移响应均大幅增加；地震动的失相干效应越明显，桥梁拱肋的内力越大，位移越小；行波效应对桥梁结构的地震反应没有较为明确的影响规律，但不可忽略其作用，仅考虑行波效应会严重低估下部结构的地震响应；在大跨度桥梁结构的地震响应分析中，应着重考虑地震动的空间变异性效应，并且准确衡量各因素的作用. 

Seismic Response of Continuous Beam-Arch Bridge under Spatially Varying Ground Motions

In order to investigate the dynamic responses of a long-span continuous beam-arch bridge subjected to multi-support and multi-dimensional ground motions, a finite element model for a concrete-filled steel tubular arch bridge with a span of 139 m in South China was built using OpenSEES software. The spatially varying ground motions were artificially simulated to investigate the effects of the coherency loss, local site conditions, and wave-passage. The results show that the spatially varying ground motions have significant influence on the dynamic responses of bridge, and considering uniform excitations only might overestimate the responses. The influence of the local site effect on the seismic responses of the bridge is the most prominent. With softer site conditions at the support points, the inner forces and displacements responses of each part of the bridge are greatly increased. Weakly correlated ground motions can lead to larger arch inner forces and smaller arch peak displacements. Although the wave-passage effect has no obvious tendency, its influence is not negligible. Only considering the wave-passage effect may seriously underestimate the seismic responses of the bridge substructure. Therefore, the spatially varying ground motions should be considered in the seismic responses analysis of long-span bridges, and the effect of each factor should be accurately measured.