考虑碰撞效应的近断层斜拉桥地震响应研究

Seismic Responses of Cable-Stayed Bridge Considering Ponding Effect under Near-Fault Ground Motions

为了研究碰撞效应对近断层斜拉桥地震响应影响,该文以一座双塔斜拉桥为工程背景,分析近断层地震动作用下斜拉桥主桥和引桥主梁碰撞响应及碰撞响应对结构地震响应的影响,研究黏滞阻尼器和弹性索对近断层地震动作用下斜拉桥碰撞效应影响,并与远场地震动下斜拉桥地震响应进行对比,探讨碰撞效应对斜拉桥减震率影响。结果表明:与无脉冲地震动相比,近断层脉冲地震动作用下在脉冲时段内斜拉桥主桥与引桥更易发生碰撞,碰撞效应对斜拉桥地震响应影响更显著;设置黏滞阻尼器和弹性索后,斜拉桥主桥与引桥在脉冲时段内仍发生碰撞,但碰撞响应减小,且脉冲地震动作用下碰撞效应对斜拉桥地震响应影响明显降低;在分析脉冲地震动作用下斜拉桥减震率时须考虑碰撞效应。

To study the influence of the ponding effect on seismic responses of the cable-stayed bridge under near-fault ground motions,taking a double-tower cable-stayed bridge as the engineering background,this paper analyzed the ponding response of the main bridge and the main beam of the approach bridge of the cablestayed bridge under near-fault ground motions and the influence of the ponding response on the structural seismic response.Besides,the influence of viscous dampers and elastic cables on the ponding effect of the cable-stayed bridge under near-fault ground motions was studied,which was compared with the seismic response of the cable-stayed bridge under far-fault ground motions to discuss the influence of the ponding effect on the seismic mitigation rate of the cable-stayed bridge.The results show that compared with non-pulse ground motions,under near-fault pulse-type ground motions,the main bridge and approach bridge of the cable-stayed bridge are more likely to collide within the pulse period,and the influence of the ponding effect on the seismic response of the cable-stayed bridge is more significant.When viscous dampers and elastic cables are installed,the main bridge and approach bridge still collide within the pulse period,but the ponding response decreases.Besides,the influence of the ponding effect on seismic responses of the cable-stayed bridge under pulse-type ground motions is significantly reduced,and the ponding effect should be considered when the seismic mitigation rate of the cable-stayed bridge under pulse-type ground motion is analyzed.