荷麻溪大桥动力特性与地震反应谱分析

Analyses of Dynamic Characteristics and Seismic Response Spectrum of Hemaxi Bridge

研究目的:为检验双塔单索面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。研究结论: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;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。地震反应谱分析结果表明,主桥结构关键部位基本保持弹性,满足抗震设计要求。

Research purposes： A three-dimensional finite element model was developed in order to verify the seismic performances of the Hemaxi Cable-stayed Bridge with double towel and single cable plane.The dynamic characteristics and seismic response spectrum of Hemaxi Bridge were analyzed.By using the standard seismic response spectrum as the input spectrum curve and on consideration to the seismic response of the bridge under the effects of the longitudinal,transverse and vertical responses inputs respectively,the research was done on the internal force and deformation of the bridge structure under the seismic effect and the seismic performance of the bridge was analyzed.Research conclusions：The analysis of the dynamic characteristics indicated that the first order vibration mode of the Hemaxi Bridge was of vertically symmetrical bend,so the bridge had much response to the vertical earthquake.The second vibration mode was of move in longitudinal direction,so larger bend and shear forces could appear in the joint of the bridge pier and main girder under longitudinal earthquake.The response spectrum results showed that the important components of bridge still remained the elasticity that could satisfy the requirements of seismic design.