【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。更多还原

【Abstract】 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 elasticplastic seismic responses of the bridge was analyzed by the nonlinear dynamic time-history method.The results of the analysis suggest that the yielding of the piers of the bridge takes place ahead 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+Ezin 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 El-Centro seismic wave and the critical input directions of the combination,the nonlinear displacement ductility ratios of both the Fuzhou and Pingtan sides of the piers No.9and No.10 increase and the maximum value can reach 3.38 that is not advantageous 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.更多还原