减隔震规则桥梁的模态分析方法研究

Research on Modal Analysis Method of Isolated Regular Bridges

为改善模态分析方法应用于减隔震规则桥梁的计算精度,以高速铁路典型简支梁桥为研究背景,基于位移反应谱提出一种能够考虑高阶模态的分析方法。通过选取强震记录调整后进行非线性时程分析,与现有的基于加速度反应谱和基于位移反应谱的单模态简化分析方法进行计算精度的比较。分析结果表明,相比常规的单模态分析方法,考虑了高阶模态后的基于位移反应谱多模态分析方法更为准确。基于加速度谱的单模态分析方法严重低估了墩顶位移,误差超过60%;仅考虑基阶模态的基于位移反应谱的分析方法将低估墩底剪力,误差超过30%,造成设计偏于不安全;而基于位移反应谱的多模态分析方法能够更为准确地估算各项地震响应参数。

In order to improve computational accuracy of the modal analysis method for isolated regular bridges,taking simply-supported girder bridges of high-speed railway as the research background,a modal analysis method including higher order mode based on displacement response spectrum is presented.Through nonlinear time-history analyses with adjusted strong earthquake records,this method is compared with the existing simplified single mode analysis method based on acceleration response spectrum and displacement response spectrum,The results show that the multimode analysis method considering higher order mode based on displacement response spectrum is more accurate than conventional single mode analysis method.The pier top displacement is underestimated by the single mode analysis method based on acceleration response spectrum with error exceeding 60%,and the shear force at the pier bottom is underestimated with error over 30%,resulting in unsafe seismic design.Seismic response parameters are accurately estimated by multimode analysis method based on displacement response spectrum.