不对称双塔斜拉桥多点激励作用下地震响应分析

Research on the Seismic Performance of Asymmetric Double-Tower Cable Stayed Bridge under Multi-support Excitation

针对某一大跨度不对称双塔斜拉桥"塔高且不等高、桩较长、跨度大、弱阻尼"的特点,首先建立了基于大质量法的结构地震动方程。考虑到该桥桥址处局部场地人工填土土层较厚,两岸地质相异,对该桥进行了多点激励和局部场地效应分析,重点对比了主塔塔顶、梁端纵向位移及塔底根部弯矩等地震响应规律。结果表明,考虑行波效应后该桥结构内力响应和位移响应均略小于一致激励的结果,而考虑场地效应后结构位移响应增加明显但内力响应略有减小。研究成果可为类似工程提供有益的参考。

For a long-span asymmetric cable-stayed bridge with two pylons,with the feature of unequal high pylon,long pile,long span and weak damping,the equations of structural ground motion are first established based on the large mass method. Considering the thick artificial filling of local site and the both sides＇ different geology,the effect of multi-support excitation and local site are analyzed,the contrast of the seismic response law of the longitudinal displacement of the tops of main pylon,the longitudinal displacement of the beam end and the moment of the pylon footings is carried out. The results show that： the structure force response and displacement response of the bridge are slightly less than the results of uniform excitation after considering the traveling wave effect,but the structure displacement response increases obviously and force response decreases slightly after considering the site effect. The results can provide a useful reference for similar projects.