荷麻溪大桥动力特性与地震反应谱分析

Dynamic Characteristics and Response Spectrum Analysis of Hemaxi Bridge

为检验双塔单索部分斜拉桥的抗震性能,建立荷麻溪大桥的动力特性分析力学模型,运用有限元方法进行动力特性与地震反应谱分析.采用标准反应谱作为输入的谱曲线,分别考虑纵向、横向和竖向输入下该桥的地震响应,研究地震作用下结构的内力和变形,分析该桥的抗震性能.结构动力特性分析表明:荷麻溪大桥的1阶主振型为对称竖弯,因此大桥受竖向地震响应很大;大桥的2阶振型为纵移,在纵向地震作用下,桥墩和主梁连接处将产生较大的弯矩和剪力.

A three-dimensional finite element model of Hemaxi Bridge is developed in order to verify the seismic performances of single cable plane extradosed bridge.The dynamic characteristics of Hemaxi Bridge are analyzed and the seismic response spectrum analysis is done according to current code.The standard seismic response spectrum is used as input spectrum curve,taking into account of longitudinal,transverse and vertical direction response,respectively.The internal force and displacement response are analyzed.The dynamic characteristics indicate that the first natural mode of Hemaxi Bridge is vertical symmetrical bend of main beam,which shows that the vertical earthquake input has important influence on bridge;the second mode is moving in longitudinal direction,which shows there are larger moments and shear forces in bridge pier under earthquake.