斜交简支梁桥地震碰撞反应参数分析

摘要

为研究斜交简支梁桥地震碰撞反应，采用开放式地震模拟软件 OpenSees，建立能够考虑梁体与桥台间纵向碰撞、摩擦作用及梁体与挡块间横向碰撞效应的斜交简支梁桥精细化动力计算模型，分析水平地震动输入方向、竖向地震动和斜度等对斜交简支梁桥地震碰撞反应的影响规律。结果表明：忽略横向碰撞时，斜度为α的简支梁桥梁端纵向最大位移、上部结构峰值转角在水平地震动以角度θ＝90°－α输入时达到极小值；考虑横向碰撞后，由于挡块的有效限位作用，梁端纵向最大位移、上部结构峰值转角会减小，竖向地震动对地震碰撞反应的数值有一定影响，但对其随斜度的变化规律没有明显影响，钝角处支座上拔力随斜度增大而增大，锐角处支座上拔力随斜度增大而减小，且支座上拔力由钝角处向锐角处逐渐减小，考虑水平地震动输入方向影响时，梁端纵向最大位移随斜度增大而增大，上部结构峰值转角、梁端纵向最大碰撞力随斜度增大呈先增大后减小的变化规律，梁体与挡块间横向最大碰撞力随斜度的增大总体变化不大。%To study seismic pounding responses of a skewed simply-supported girder bridge (SSGB),a refined dynamic calculation model considering effects of longitudinal impact and friction between girder and abutment,and transverse impact between girder and retainer for SSGB was built with the open style seismic simulation software OpenSees.The effects of horizontal direction ground motion,vertical ground motion and skew degree on the seismic pounding responses of SSGB were analyzed.The results indicated that if neglecting the transverse pounding effect,the maximum longitudinal displacement of the girder bridge end and the peak rotation angle of the superstructure for SSGB with the skew degree αreach their minimum values when the input direction of horizontal ground motion is θ=90°-α;if considering the transverse pounding effect,the maximum longitudinal displacement and the peak rotation angle decrease because the retainer can limit effectively the displacement of the superstructure;the vertical ground motion has a certain impact on the values of the seismic pounding responses,but has no obvious impact on the responses change law versus skew degree;the uplift forces of bearings in obtuse angle zone increase,those in acuteangle zone decrease with increase in skew degree,and those decrease from obtuse angle zone to acute angle zone;considering the effect of input direction of horizontal ground motion,the maximum value of the longitudinal displacement of the girder bridge end increases with increase in skew degree,the peak rotation angle of the superstructure and the maximum longitudinal pounding force firstly increase and then decrease with increase in skew degree,the maximum transverse pounding force between girder and retainer changes less with increase in skew degree.