地震动输入方向对铁路部分斜拉桥地震响应的影响  

Effect of Input Directions of Seismic Ground Motion on Seismic Responses of a Railway Extradosed Bridge

作　　者：李小珍[1] 洪沁烨 雷虎军[2] 刘桢杰 

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]福建工程学院土木工程学院,福建福州350118

出　　处：《桥梁建设》2015年第1期26-32,共7页Bridge Construction

基　　金：国家自然科学基金项目(51378429);国家重点基础研究发展计划(973)课题(2013CB036301);国家高科技研究发展计划(863)课题(2011AA11A103)~~

摘　　要：为研究竖向地震动分量对部分斜拉桥地震响应的影响及最不利地震动输入方向,以某跨度为(144+288+144)m的铁路部分斜拉桥为背景进行分析。采用MIDAS Civil建立全桥弹塑性有限元模型,采用Clough模型模拟塑性铰,由非线性动态时程法分析竖向地震动及水平地震动输入方向对部分斜拉桥弹塑性地震响应的影响。结果表明:考虑竖向地震动后桥墩屈服时刻提前;墩顶最大位移增大,墩底弯矩减小、轴力增大。三向地震动Ex+Ey+Ez和0.3Ex+0.3Ey+Ez两组合工况下,地震动最不利水平输入方向均为140°;El-Centro波作用时,两组合工况的最不利方向下,9号、10号墩福州和平潭两侧墩身的非线性位移延性比均增大,最大值达到3.38,不利于延性抗震。地震反应分析应当考虑竖向地震动、水平地震波最不利输入方向的影响。To study the effect of the vertical seismic ground motion component on the seismic responses of extradosed bridge and the critical input directions of the ground motion, a railway extradosed bridge with span arrangement （144＋288＋144） m was cited as an example and was analyzed. The MIDAS Civil was used to establish the elastic-plastic finite element model for the whole bridge of the bridge, the Clough model was used to simulate the plastic hinges and the effect of the input directions of the vertical and horizontal seismic ground motion on the elastic- plastic seismic responses of the bridge was analyzed by the nonlinear dynamic time-history meth- od. The results of the analysis suggest that the yielding of the piers of the bridge takes place a- head of time when the vertical seismic ground motion is considered. The maximum displacement of the pier tops increases, the bending moment of the pier footings decreases and the axial force increases. Under the combination of the two kinds of the ground motion of the Ex＋Ey＋Ez in three directions and the 0.3Ex＋0.3Ey＋Ez., the critical input directions of the ground motion are all 140°. Under the action of the EI-Centro seismic wave and the critical input directions of the combination, the nonlinear displacement ductility ratios of both the Fuzhou and Pingtan sides ofthe piers No. 9 and No. 10 increase and the maximum value can reach 3.38 that is not advanta- geous to the ductility seismic resistance. In the seismic response analysis, the effect of the critical input directions of the vertical and horizontal seismic waves should be considered,

关 键 词：铁路部分斜拉桥 塑性铰 竖向地震动 输入方向 地震响应 非线性分析 有限元法 

分 类 号：U448.27[建筑科学—桥梁与隧道工程] U442.59[交通运输工程—道路与铁道工程]