考虑碰撞和支座影响的桥梁近场竖向地震响应分析

Near-fault vertical earthquake response analysis of bridge considering pounding and bearing

为了精确计算带支座桥梁的近场竖向地震响应,研究了桥梁支座和竖向碰撞现象对桥梁地震响应的影响。建立了针对双跨连续梁桥的梁-弹簧-杆连续体模型,运用瞬态波特征函数展开法和组合体瞬态内力法求解了桥梁结构中地震响应和碰撞响应耦合的理论解。计算结果表明,该文方法能计算多次碰撞后桥梁结构复杂的内力响应。在近场竖向地震和多次碰撞作用下,桥梁跨中正弯矩、支座处负弯矩和桥墩底部应力高频高幅值振荡可能超过其承载能力。竖向地震提前于水平地震激励的时间越长,由单独的竖向地震引起桥梁破坏的可能性就越大。

To precisely calculate the near-fauh vertical earthquake response of bridge with bearings, the effect of the bridge bearing and the vertical pounding on the bridge seismic response is researched. A continuous model of beam-spring-rod is applied to analysis earthquake responses of a two-span continuous beam bridge. The theoretical solutions of coupling responses of earthquake and pounding are obtained by the expansion of transient wave functions in series of eigenfunctions and the transient internal force of the contact surface of the combined impact body. The numerical results show that the present model and method can simulate reasonably the pounding phenomenon and calculate the complex responses of bridge with poundings. The positive moment of the bridge mid- span section, the negative moment of bridge above bearing section and the axial force of pier are sig-nificantly enhanced by near-fauh vertical earthquakes, which even exceed ultimate carrying capacity of the bridge and lead to its damage. The longer the time of vertical earthquake ahead of horizontal earthquake is, the greater the probability leading to bridge damage only under the vertical earthquake is.