5跨连续中承式钢管混凝土拱桥抗震性能分析

钢管混凝土拱桥由于桥型优美在城市桥梁中得到广泛应用，对某正在设计的5跨连续巾承式钢管混凝土拱桥进行了动力特性和抗震性能分析，根据该桥的结构特点，建立了’该桥的空间有限元分析模型，计算桥梁的自振特性，基于反应谱方法计算了该桥在横向、纵向水平地震反应，计算结果表明：该桥拱肋的面外刚度相对较小，在桥梁振动中首先出现拱肋的面外振动；桥梁的竖向振动表现为拱肋与桥面的整体竖向振动，其基频明显比拱肋面外振动大；主拱肋的轴力由横桥向地震动控制，其他内力由纵桥向地震动控制；地震作用对弯矩的影响较大，故主拱的内力计算应考虑地震力的影响；在设计计算中除常规关键点应作为控制点外，内外拱连接处也应作为控制点。计算结果已为该桥的抗震设计提供了参考。

Seismic behavior analysis of a 5-span continuous half-through CFST arch bridge

CFST(concrete filled steel tube) arch bridges with elegant configuration are widely applied in city bridges. In this paper the dynamic property and seismic response behavior of a 5-span continuous half-through CFST arch bridge during design are analyzed. According to the structural feature of the bridge, spatial finite element analysis model is established to calculate its natural vibrations. The longitudinal and transverse seismic responses in the plane of the bridge deck are calculated by the response spectrum method. The calculated results show that the stiffness of arch ribs out of plane is smaller. The out of plane vibrations of the arch ribs first happen in the bridge vibration; the vertical vibrations of the bridge reveal the integral vertical vibrations of the arch ribs and the bridge deck system, the fundamental frequency of the bridge's vertical vibrations are larger than that out of plane; the axial forces of main arch ribs are controlled by seismic forces in the transverse direction of the bridge whereas the rest are controlled by seismic forces in the longitudinal direction of the bridge; seismic actions exert a considerable effect on bending moments, so the influence of seismic actions on internal forces of main arch should be considered; besides routine key points which should be regarded as reference points, the points at the joint of inside and outside arch ribs should also be regarded as reference points. The computational results of the paper have been applied to seismic design of the bridge.