基于非线性土桩作用的高速公路斜拉桥直塔和折线塔抗震性能分析

Seismic Performance Analysis of Straight Tower and Broken Line Tower of Expressway Cable Stayed Bridge Based on Nonlinear Soil Pile Action

以某高速公路斜拉桥为研究对象,对非线性土桩相互作用下的斜拉桥抗震性能进行了研究。结果表明,高速公路上的斜拉桥中土桩的塔型变化对于整个斜拉桥无论是从组成结构、质量水平上均无太大影响,我们通过对塔型进行了两种改变模式,直塔和折线塔从模型形态、震动频率等方面并无差异。在振型频率相同时,结构体系2的频率压比结构体系1的低,采用不对称体系,结构抗震性能变化较小。在地震荷载作用下,两种体系梁端位移和塔顶位移相差较小;在结构体系1条件下,受纵向地震的作用,在塔梁墩固结边跨侧,折线塔斜拉桥拉索索力略比结构体系2的要高,在其它位置则基本吻合;相比于直塔斜拉桥相应索索力,折线塔斜拉桥边跨边索索力略高,中跨边索索力则略低;而在直塔和折线塔的结构塔型上分析而得,当我们纵向的感受到地震波动的时候,两种塔型斜拉桥所受到拉伸力呈现基本对称状态。

In this paper,the seismic behavior of a cable-stayed bridge under nonlinear soil-pile interaction is studied.The results show that the change of pylon shape has little effect on the overall quality and stiffness of cable-stayed bridge,and the modal and natural vibration frequency of the straight tower and the broken-line tower are basically identical under the two structural systems.When the mode frequencies are the same,the frequencies and pressures of structural system 2 are lower than those of structural system 1.Under seismic load,the difference between the two systems is small;under the condition of structural system 1,under the action of longitudinal earthquake,the cable force of the cable-stayed bridge with broken-line tower is slightly higher than that of the structural system 2,and basically coincides with that of the straight-tower cable-stayed bridge.The side-span cable forces of the two pylon-type cable-stayed bridges are slightly higher than that of the middle-span cable-stayed bridges.