大跨度斜拉拱桥地震响应分析

以湘潭市在建的一种新颖钢管混凝土拱桥——斜拉钢管混凝土拱组合桥梁为研究对象,通过大型有限元软件建立空间结构有限元模型,利用子空间迭代法对其进行了模态求解,得到并分析了结构的动力特性。在此基础上分别运用反应谱法和时程反应法分析了该桥的纵向、横向和竖向地震响应,采用了5条实际记录地震波,讨论其主要结构形式、不同的地震波、各种场地以及各参数对地震反应的影响和规律。研究结果表明,大跨度斜拉钢管混凝土拱桥横向稳定性突出,整体抗震性能较好,这为大跨度斜拉拱桥的抗震设计和研究提供了理论依据。

Analysis of Seismic Response for Cable-Stayed Arch Bridge

The forth bridge of Xiangtan with a main span of 400 m is a long span cable-stayed concrete-filled steel tubular arch bridge.In this paper,a 3-dimensional finite element model for the bridge is established.Based on the model and the dynamical equation of MDOF structural system,model analysis is carried out by use of subspace method.Then the dynamic characteristics of the bridge is obtained and analyzed.In addition,3D seismic response of this bridge is studied by means of seismic response spectrum method and time history method.With more than five selected seismic records,the effects of the main structural form,different seismic waves and several soil sites on seismic response have been discussed.Conclusions can be drawn as follows:1.The lateral stability of long span cable-stayed concrete-filled steel tubular arch bridge is notable.2.The whole aseismic capabilities of the bridge is better than long span concrete-filled-steel-tube(CFST) arch bridge.The internal force of arch is evenly distributed,under plane earthquake input or vertical earthquake input.The internal force of tower is also very small.3.The structural seismic response is influenced greatly by the characteristics of different seismic waves,such as natural vibration period and soil sites.4.The maximum seismic response of long span cable-stayed concrete-filled steel tubular arch bridge appears in arch spring and transition section,which should be considered in bridge design.The results obtained in this paper also provide theoretic basis for seismic design and study of cable-stayed arch bridge.