高墩大跨连续刚构桥地震响应需求的模态推倒分析法

摘要

基于结构动力学多自由度体系解耦思想,提出适用于高墩大跨连续刚构桥的模态推倒分析法(MPA).结合现行规范设计反应谱,以某高墩大跨连续刚构桥为工程背景,采用OpenSEES软件建立全桥非线性纤维模型,分别对MPA法和非线性时程法进行对比研究.结果表明:MPA法对高墩剪力的计算误差相对较大,尤其在纵桥向,最大达到34.73％,而横桥向则满足工程应用需求,最大为26.48％;MPA法对高墩弯矩和位移的计算结果在纵、横桥向都非常接近时程结果,计算精度完全满足工程应用要求.总体而言,MPA法可直接用于评估高墩连续刚构桥的横向抗震性能,且精度很高,但用于纵向抗震性能评估时,需考虑剪力的计算误差对评估结果的不利影响.%Based on the mode decoupling method of multi-degree-of-freedom systems in structural dynamics,modal pushover analysis (MPA) was proposed to be used in the seismic performance evaluation of large-span continuous rigid frame bridges with high piers.In combination with the design spectrum in current Chinese code,the OpenSEES platform was adopted to establish the nonlinear fiber analytical model for a large-span continuous rigid frame bridge with high piers.The MPA method and time history method were compared in estimation of seismic response of the bridge.The results showed that the MPA produces relative large errors in determination of the pier shear forces,especially in the longitudinal direction with the maximum error of 34.73％.In the transverse direction,the MPA method can be used in engineering practice and the maximum error is 26.48％.The MPA method leads to results of pier moment and displacement,which are very close to those of the time history method in both longitudinal and transverse directions.And the calculation precision satisfies the requirements of engineering practice.The analysis results show that the MPA method can be used directly to evaluate with satisfactory accuracy the transverse performance of continuous rigid frame bridges with high piers.While applying this method to assess the longitudinal performance,special attention needs to be paid to the influence of calculation error in shear demand on the final assessment results.