不同激励下大跨度CFST拱桥地震反应时程分析

Time-history Analysis on Seismic Response of Long-span CFST Arch Bridge under Different Excitations

以茅草街大桥为研究对象,基于ANSYS软件建立了该大跨度中承式钢管混凝土(CFST)系杆拱桥的三维有限元模型,并对其进行了自振特性分析,获得了结构的自振频率和振型。以此为基础,结合以Fortran PowerStation 4.0为平台编制的计算程序对茅草街大桥的地震反应进行了空间非线性时程分析,计算了一致、行波和多点输入下该桥的地震反应,分析比较了不同激励方式对于大跨度CFST拱桥地震反应的影响。结果表明,行波输入对该桥地震反应最为不利,使得结构关键截面内力显著增加;多点输入对结构地震反应的影响比较复杂,使有些构件内力反应增加,有些减小,但增加和减小的幅度不大。

The demonstrated Maocaojie Bridge is a concrete-filled steel tube（CFST） arch bridge with a main span of 368m. It is the 3 largest CFST arch bridge in the world. Based on ANSYS, a 3-dimensional finite element model for the bridge is established and the dynamic behavior of the bridge is then analyzed. On the basis of which the seismic response time-history analysis of the bridge under consistent excitation, multiplepoint excitation and traveling wave excitation are carried out. The response of forces and displacements in key sections of the bridge under different excitations are investigated and compared with each other. Results show that the structural responses are closely related to the way of seismic excitations. The bridge is most dangerous by use of the traveling wave excitation, under which the structural responses of key sections are increased obviously ; while the structural responses is complicatedly affected by the multiple-point excitation, under which the structural responses of some sections are increased, but others are decreased.