空间变化地震作用下钢管混凝土拱桥的抗震分析

为了研究空间变化地震作用下钢管混凝土拱桥的抗震性能，以一座钢管混凝土拱桥的实际工程为例，采用虚拟激励法对此拱桥在空间变化地震作用下的抗震性能进行了系统的理论分析。提出了考虑非一致土层分布条件下的空间三维地震动的合成方法，在综合考虑地震动的多维性、不相干效应、行波效应，特别是一致和非一致土层分布条件下局部场地效应的基础上，对钢管混凝土拱桥进行了多维多点随机振动分析。研究结果表明:场地效应会对结构产生显著的影响，软土场地会导致结构产生较大的响应，同时非一致的土层分布也会对结构响应产生不可忽略的影响；地震动的多维性，特别是竖向地震激励会对拱桥结构响应产生较大影响；在抗震分析中应考虑这些因素的影响，以免错误的估计结构的响应。

STOCHASTIC SEISMIC ANALYSIS OF A CFST ARCH BRIDGE UNDER SPATIALLY VARYING GROUND MOTIONS

This paper presents a comprehensive theoretical analysis of an actual concrete-filled steel tubular (CFST) arch bridge under tridirectional spatial motions using the pseudo-excitation method (PEM). Formulations for modelling tridirectional spatial motions at varying sites are derived. Then, stochastic seismic analysis of the CFST arch bridge is conducted, by considering the dimensionality, incoherence effect, wave-path effect of ground motions, and local site effects with different and irregular site conditions. It is concluded that 1) the site effect can significantly affect structural responses; 2) the softer site conditions can amplify the larger structural responses; 3) the varying and irregular site conditions can induce significant variations of structural responses; 4) effect of dimensionality of earthquake motions and inclusion of the vertical ground motions should be considered in the seismic analysis to avoid erroneous response predictions.