地震动关键特性对隔震连续梁桥碰撞响应的影响

为考虑地震动特性对隔震连续梁桥顺桥向主梁与桥台碰撞响应的影响,以某三跨混凝土隔震连续梁桥为例,基于ABAQUS建立了考虑混凝土材料损伤及三维接触碰撞的有限元模型。采用12条典型地震动输入,分析了不考虑碰撞时地震动峰值加速度与峰值速度的比值(PGA/PGV)对主梁顺桥向最大位移的影响;并进一步分析了考虑碰撞效应时PGA/PGV对主梁碰撞响应的影响;在此基础上,以一条典型地震动为例,分析了地震动峰值加速度对碰撞响应的影响。结果表明,当不考虑碰撞效应时,主梁顺桥向最大位移随着PGA/PGV的增大而呈现减小趋势;考虑碰撞时,碰撞次数和最大碰撞力的变化具有一定的相似性,但随PGA/PGV的变化并不明显。随着伸缩缝间隙的不同,最大碰撞力随着峰值加速度的增加既可能表现出线性增加的特征,也可能表现出较大波动。

Effect of Seismic Characteristics on the Pounding Responses of an Isolated Continuous Girder Bridge

To analyze the influence of seismic characteristics on the pounding responses of isolated continuous girder bridges, the finite element program ABAQUS is used to build an analytical model for a three-span concrete bridge as an example, which considers the concrete damage plasticity (CDP) and the spatial arbitrary pounding. First, twelve typical seismic waves are used in the analysis to investigate the effect of the ratio of peak ground acceleration to peak ground velocity (PGA/PGV) on the simulated results. The maximum displacement of the girder with no pounding effect, the pounding times, and maximum pounding force with pounding effect are derived. Then, a typical ground motion is chosen to analyze the effect of PGA on the pounding response. The simulated results indicate that the maximum pounding forces and pounding times vary insignificantly with PGA/PGV, though the maximum displacement of the deck increases with the reduction of PGA/PGV when the pounding effect is ignored. With different lengths of the joint expansion, the maximum pounding force may increase linearly with PGA, or it may fluctuate with PGA.