钢塔斜拉桥地震反应特性分析

针对一个实际钢塔斜拉桥工程,采用有限元软件SAP2000进行了动力特性和地震反应分析,并以主塔为混凝土塔的苏通大桥作为参照,对斜拉桥的动力特性、主塔地震反应和抗震性能等进行了比较分析。结果表明:相对于混凝土塔,钢桥塔的刚度和质量较小,轴压比略大,斜拉桥纵飘和主塔侧弯振型周期较长,主塔重力几何刚度对桥梁动力特性的影响较大,从而显著增大了塔顶及主梁的纵向地震位移,但对主塔及其基础的地震内力影响较小。钢塔斜拉桥的抗震性能较好,在7度地震区,地震作用不会控制钢塔及其基础的结构设计。

Seismic Response Analysis of Steel-Tower Cable-Stayed Bridges

In this paper,dynamic characteristics and seismic responses of a steel-tower cable-stayed bridge are analyzed using finite element software SAP2000.In addition,a comparative analysis is conducted on Sutong Bridge with reinforced concrete(RC)towers to study the dynamic characteristics,seismic responses of main tower and seismic performance of cable-stayed bridge.The results show that steel towers have smaller stiffness and mass,while slightly larger axial compression ratio as compared to RC towers.Steel-tower cable-stayed bridges present a longer period of longitudinally floating and transversally bending modes of the main tower as compared to RC tower cable-stayed bridges.The geometric stiffness of the main tower has a significant impact on the dynamic characteristics of bridges,causing larger longitudinal seismic displacement of the tower top and main beam.However,it has little impact on the seismic force demands at the main tower and its foundation.Overall,steel-tower cable-stayed bridge presents a good seismic performance.Seismic responses do not control the structural design of the steel-towers and foundations in seismic region of magnitude 7.