近断层地震对飞鸟式钢管混凝土拱桥作用效应

Effects of Near-fault Ground Motions on Flying Birds Type Concrete-filled Steel Tube Arch Bridge

借助有限元软件ANSYS建立了飞鸟式钢管混凝土拱桥杆系模型,选取近断层强震记录作为输入,讨论了地震动自身频谱特性及其对结构的作用效应。通过非线性时程反应分析,对比研究了飞鸟式钢管混凝土拱桥的内力和位移响应。结果表明,不能简单认为输入地震动的卓越频率更接近于结构基频就认为一定会导致更严重的地震反应。长周期大跨结构更易受低频加速度脉冲的破坏作用,拱肋与桥面交汇处地震作用效应加剧,是脉冲型近断层地震破坏作用的相对薄弱部位。

Based on the finite element software ANSYS,a truss model of flying birds type concrete-filled steel tube（ CFST） arch bridge is established. The near-fault strong earthquake records are selected as the input,and the ground motion spectrum characteristics and its seismic effect on the structure are discussed. Through the nonlinear time-history analysis,the internal force and displacement response of the structure are studied. The results reveal that although the predominant frequency of the input ground motions is more close to the structural fundamental frequency,it will not surely lead to more serious seismic response. The long period large-span structure is tended to be subject seismic action obviously by low-frequency acceleration pulse. The intersection of the arch rib and the deck is a weak position under the action of a pulse-type ground motion,and the seismic effect is aggravated accordingly.