公轨两用大跨度单索面钢桁梁斜拉桥动力特性研究

Study on Dynamic Characteristics of Rail-Cum-Road Cable-Stayed Bridge with Long Span, Single Cable Plane and Steel Truss Girder

以某公轨两用大跨度单索面钢桁梁斜拉桥为背景,采用有限元结构分析软件MIDAS/Civil 2019建立考虑施工阶段的全桥3维有限元模型,考虑几何非线性并采用子空间迭代法对桥梁振型进行分析,对索面布置、恒载集度、塔刚度、索刚度、梁刚度、辅助墩数量进行参数改变,研究其对桥梁动力特性的影响。结果表明:单索面钢桁梁双塔斜拉桥抗弯、抗扭刚度较弱,将单索面布置改为双索面布置,可增强斜拉桥的抗扭刚度,并在一定程度上避免弯扭耦合振型的出现;选择轻型2期恒载可增强桥梁的抗震、抗风稳定性;提高塔和梁的刚度可增强桥梁的抗震和抗风稳定性,但索刚度的变化对桥梁动力特性影响较为复杂;科学地增设辅助墩可优化桥梁的动力性能。

A rail-cum-road cable-stayed bridge with long span, single cable plane and steel truss girder was taken as the background. Midas/Civil 2019, the finite element structural analysis software, was used to build a 3D finite element model of the whole bridge considering the construction stage. Taking account of the geometric nonlinearity, the subspace iteration method was used to analyse the vibration mode of the bridge. The influence of cable layout, dead load concentration, tower rigidity, cable rigidity, girder rigidity and the number of auxiliary piers on the dynamic characteristics of bridge was studied by parameter transformation. Results show that the bending and torsional rigidities of the double-tower cable-stayed bridge with single cable plane and steel truss girder are weak. Changing the layout of single cable plane to that of double cable plane can enhance the torsional rigidity of the cable-stayed bridge and avoid the occurrence of bending torsional coupling vibration mode to a certain extent. The second stage light dead load can enhance the anti-seismic and anti-wind stability of the bridge. The improvement of the rigidities of the tower and girder can enhance the anti-seismic and anti-wind stability of the bridge, but the change of cable rigidity has complex influence on the dynamic characteristics of the bridge. The dynamic performance of the bridge can be optimized by adding auxiliary piers scientifically.