大跨度上承式钢筋混凝土拱桥行波效应分析

Analysis on Traveling Wave Effect of Long-span Deck Reinforced Concrete Arch Bridge

摘要:

为探究地震行波效应对大跨度上承式拱桥关键部位内力的影响规律，为同类桥梁抗震设计提供参考，选取云南某115 m上承式钢筋混凝土拱桥工程案例，建立MIDAS Civil空间有限元模型，分析桥梁动力特性，地震输入采用动态时程分析法，对比分析了不同波速工况下拱圈及拱上立柱的内力响应。结果表明行波效应显著影响结构内力分布与幅值，拱脚处轴力、剪力及弯矩变化明显，拱顶弯矩变化尤为显著。得出结论：行波效应可能导致关键截面内力大幅增加，建议在抗震设计中兼顾一致激励与非一致激励分析，以确保结构安全。

Abstract:

To investigate the influence of seismic traveling wave effects on the internal forces in critical sections of long-span deck arch bridges and to provide the references for seismic design of similar structures, a 115-m deck reinforced concrete arch bridge in Yunnan is selected as an engineering example, and a MIDAS Civil finite element model is established to analyze the dynamic characteristics of the bridge. The dynamic time-history analysis method is used for the seismic input, and the comparative analysis is conducted on the internal force responses of arch ribs and spandrel columns under the different wave velocity conditions. The results indicate that traveling wave effects significantly influence the distribution and amplitude of internal forces in the structure. The axial force, shear force and bending moment at the arch foot change significantly. And the change in the bending moment of the vault is particularly significant. The conclusion is that the traveling wave effects may cause the great increases in internal forces at critical sections. It is suggested that both consistent and inconsistent excitation analyses should be taken into account in seismic design to ensure structural safety.