大跨钢箱梁悬索桥地震响应有限元分析

Finite element analysis on seismic response of large-span steel box girder suspension bridge

根据某大跨钢箱梁悬索桥的设计图纸,采用ANSYS建立其有限元模型,采用壳单元对主梁进行模拟.通过不断调试找出最佳的主缆初始应力,完成悬索桥的初始找形分析.对悬索桥进行预应力模态分析,采用瑞利阻尼理论,通过悬索桥有限元模型的前2阶圆频率计算模型的质量阻尼和刚度阻尼.采用动力时程分析法对悬索桥进行地震响应有限元分析.结果表明:横桥向位移的最大峰值由横桥向地震波输入决定,纵桥向位移的最大峰值以及竖桥向位移的最大峰值主要由重力载荷工况决定,地震载荷工况对其贡献非常小.

According to the design drawings of a large-span steel box girder suspension bridge, ANSYS is used to build its finite element model and its main girder is simulated by shell element. Through continuous debugging, the best initial stress of the main cables is found out and the initial form-finding analysis is achieved for the suspension bridge. The prestressed modal analysis is performed on the suspension bridge. Using the Rayleigh damping theory, the mass damping and the stiffness damping of the model are calculated through the first two order circular frequencies of the finite element model of suspension bridge. The dynamics time history analysis method is used to perform the seismic response finite element analysis of the suspension bridge. The results show that, the maximal peak value of displacement in the transverse direction of the bridge is determined by the seismic wave input in the transverse direction of the bridge; the maximal peak values of displacement in the longitudinal direction and the vertical direction of the bridge are determined by the gravity load condition, while the seismic load condition makes a little contribution on them.