南京江心洲大桥主桥的地震反应谱分析

Seismic Response Spectrum Analysis of Main Bridge of Jiangxin Island in Nanjing

以南京江心洲大桥主桥为研究对象,采用大型有限元分析软件ANSYS建立了该独塔自锚式悬索桥的三维有限元模型,采用子空间迭代法对该桥模型进行了自振特性的分析,在其中考虑了几何非线性的影响。对该桥模型进行模态分析。在此基础上运用反应谱法计算了该桥的纵向、横向、竖向、纵向+竖向以及横向+竖向的地震响应,并针对其主要截面位置进行分析。结果表明,横向地震下的塔底应力比纵向、竖向输入下大,竖向地震作用下主梁地震应力要比横向、纵向地震作用下的大,塔顶位移在纵向+竖向地震动输入时的位移值最大等。研究结果对同类桥型的工程抗震研究具有参考意义。

A 3D finite element model of the single-tower and self-anchored suspension bridge, the main bridge of Jiangxin island in Nanjing, was established with the software ANSYS to analyze its natural vibration property with the subspace iteration method considering the influence of the geometrical nonlinearity. The method of response spectrum analysis was used to calculate the seismic responses of the bridge under earthquakes in longitudinal, transversal, vertical, longitudinal＋vertical, and transversal＋vertical directions; and the seismic response on main cross-sections of the bridge were further analyzed in detail. The result shows that the stress at the tower bottom under the transversal earthquake is greater than that under the longitudinal or the vertical earthquake; the stress on the bridge deck under the vertical earthquake is greater than that under the transversal or the longitudinal earthquake; the displacement at the tower top assumes its maximum value under the combination of longitudinal＋vertical earthquakes. And it can offer a reference for the seismic analysis of the same type of bridges.