基于增量动力分析和纤维模型的矮塔斜拉桥结构抗震性能研究

Study on the Seismic Analysis of the Lower-tower Cable-stayed Bridge Based on IDA and Fiber Model

基于OpenSees软件及其纤维模型的有限元方法,建立了典型矮塔斜拉桥的非线性数值分析模型,分析各构件的抗震性能指标。采用动力增量分析法(即IDA方法),对结构进行了非线性动力时程分析,分别探讨了在纵桥向和横桥向地震作用下矮塔斜拉桥结构的构件破坏规律。分析了在不同加速度峰值情况下,矮塔斜拉桥主塔和边墩沿高度变化的应变包络图、主梁内力包络图及支座位移包络图。结果表明:与一般斜拉桥性能要求不同,矮塔斜拉桥的主塔可以发生损伤,塔底和边墩墩底为主要控制截面,支座在纵桥向地震组合作用下较易发生破坏,拉索和主梁是不易损伤的构件,主梁内力包络图的分布情况随着地震峰值的增加发生变化。

A nonlinear finite element model of lower-tower cable-stayed bridge is built based on the fiber model. The performance index of the elements is discussed. Incremental Dynamic Analysis is employed in transversal and longitudinal damage analysis concerning the participation of vertical ground motion.Steel strain of the main towers and side piers as well as concrete strain,stress of cables and moment of main beams is presented as seismic response of structural components. Strain and internal force envelope figures are analyzed considering different peak acceleration effect. The results show that the behavior of lower-tower cable-stayed bridge is different with that of the cable-stayed bridge. The tower in the former is allowed to damage. The bottoms of the tower and side pier are the main control section. Bearing supports are more prone to damage in the longitudinal direction. Cable and the girder are not easy to damage. The force envelope diagrams distribution of main beam changes with the increase of peak acceleration of earthquake.