大跨度拱桥地震动输入模式研究

地震动输入是大跨度桥梁地震反应分析的重要一环。从明确大跨度拱桥的临界跨度入手，探讨了大跨度拱桥地震动输入模式中的行波效应、三向输入及其地震动选取问题。基于某大跨度钢管混凝土拱桥，建立了有限元分析模型，考查了行波效应及三向地震动输入对拱关键截面内力、减隔震支座位移及粘滞阻尼器冲程的影响。结果表明:给出的大跨度拱桥临界跨度确定方法合理，行波效应对拱顶轴力有重要影响，不考虑三向地震动同时作用会明显低估大跨度拱桥的地震反应。确定大跨度拱桥地震动输入模式时需考虑行波效应与三向地震动同时输入。

Study on ground motion input mode of long-span arch bridges

Seismic input is an important part of seismic response analysis of long-span bridges. The critical span for long span arch bridge is defined, traveling wave effect, three-dimensional input and selection of ground motion in seismic input mode of long-span arch bridges were investigated. Based on a long-span concrete filled steel tube arch bridge, a finite element analysis model was established and performed. The traveling wave effect and three-dimensional input of ground motion on internal force of key sections for the arch bridge, the displacement of isolation bearings and the stroke of viscous dampers were investigated. The results show that the method of determining the critical span of long-span arch bridges is reasonable. The traveling wave effect has a great influence on the axial force of the vault. Three-dimensional effect and traveling wave effect of ground motion should be considered for the seismic input mode of long span arch bridge. The seismic response of long span arch bridge can be underestimated without considering the effect of three-dimensional input. The input mode of the long span arch bridge should contain the traveling wave effect and the three-dimensional ground motion input.