考虑行波效应的大跨度矮塔斜拉桥耐震时程分析

耐震时程法（ETM）是一种采用幅值随时间不断增大的人工地震动作为输入的新型动力分析方法，其只需通过少量的数值运算便可得到不同地震强度下的结构响应。基于此优势，该文探索了在考虑行波效应下，耐震时程法预测大跨度矮塔斜拉桥地震碰撞响应的精确性和有效性。以一座两侧建有桥台的典型山谷地带矮塔斜拉桥为研究对象，通过与天然地震输入下的增量动力分析（IDA）结果进行对比，验证耐震时程法捕捉地震碰撞响应的可行性；并采用此方法参数化分析了不同地震动视波速对碰撞力、塔梁位移和墩柱曲率响应的影响。研究结果表明:耐震时程法能够高效地预测出考虑行波效应的矮塔斜拉桥地震碰撞响应；此外，行波效应对大跨桥梁地震碰撞响应的影响存在两面性，与结构是否进入非线性以及地震动强度和视波速大小有关。

APPLICATION OF THE ENDURANCE TIME METHOD TO SEISMIC-INDUCED POUNDING ANALYSIS FOR LONG-SPAN EXTRADOSED CABLE-STAYED BRIDGES CONSIDERING WAVE PASSAGE EFFECTS

The endurance time method(ETM)is a novel dynamic analysis procedure in which artificially intensified accelerograms are used as loading inputs.In this method,various dynamic responses under seismic excitations of different intensity levels are estimated with a reduced simulation effort.Based on these merits,this paper investigated the accuracy and effectiveness of ETM in predicting the pounding responses of long-span extradosed cable-stayed bridges considering wave-passage effects.A typical extradosed cable-stayed bridge with two-side abutments in the valley was selected as the analyzed target,and the incremental dynamic analysis(IDA)results with natural earthquake records were obtained to make a comparison.Parametric analyses on the wave-passage effect with different apparent wave velocities were carried out by ETM.The concerned responses included the pounding force,the displacement of bridge deck and towers and the curvature ductility factors of bridge piers.The results indicate that ETM can efficiently predict the seismic-induced pounding response of long-span extradosed cable-stayed bridges with the inclusion of wave-passage effects.In addition,the dual effects of wave-passage on seismic-induced pounding response,which are related to structural nonlinearity,seismic amplitude and apparent wave velocity,were observed.