考虑行波效应的大跨度结合梁斜拉桥地震响应分析

Seismic Response Analysis of Long Span Composite Girder Cable-Stayed Bridge Considering Traveling Wave Effect

为研究行波效应非一致激励对大跨度结合梁斜拉桥地震响应的影响,以西部高烈度地区某高速公路上一座跨径为(67+110+360+110+67)m的结合梁斜拉桥为研究对象,利用ANSYS建立其空间动力模型,采用非线性时程分析法对比分析了非一致激励与一致激励作用下斜拉桥的地震响应。研究结果表明:行波效应总体上使主梁与塔顶纵向位移响应减小,随着波速的增大,位移逐渐趋于一致激励;在波速较小时,考虑行波效应的塔底截面弯矩及剪力比一致激励要小,但墩底截面的弯矩和剪力略微增大;当波速较大时行波输入与一致激励的地震响应基本相同。考虑行波效应后墩梁和塔梁间相对位移均有所增大,墩梁和塔梁间相对位移变化不规律,震荡次数减少。

In order to study the inf luence of non-uniform excitation of traveling wave effect on the seismic response of long span composite girder cable-stayed bridge,a(67+110+360+110+67)m bridge on a highway in western high seismic intensity area was selected as the research object.The spatial dynamic model was established using ANSYS,and the nonlinear time-history analysis method was used for the seismic response of the cable-stayed bridge under non-uniform and unanimously excitation.The results show that the traveling wave effect reduces the longitudinal displacement responses of the main girder and the tower top,and the displacement gradually converges with the increase of the wave velocity.When the wave velocity is small,the bending moment and the shear at the tower bottom considering travelling wave effect are smaller than those in the case of unanimously motivation,while the moment and the shear at the pier bottom are slightly larger.On the other hand,when the wave velocity is high,the seismic responses in both two cases are the same.Besides,considering the traveling wave effect,the relative displacement between the pier girder and the tower girder is increased,and the relative displacement between the pier beam and the tower beam is irregular and the times of shocks decreases.