高承台下自由桩长对双薄壁墩连续刚构桥地震响应的影响

Influence of free length of piles under high platform on seismic response of continuous rigid frame bridges with double thin-wall piers

为探究高承台下自由桩长对双薄壁墩连续刚构桥地震响应的影响,基于OpenSees程序建立了实桥有限元模型并进行弹塑性时程分析,通过对比不同自由桩长模型的时程曲线、峰值响应及滞回特性,分析了自由桩长对桥梁地震响应的影响。结果表明:自由桩长增加会减小桥梁刚度;地震作用下,随自由桩长增加,主梁、支座及自由桩顶的水平位移增大,且支座位移增幅大于主梁和桩顶的位移增幅,墩底内力及变形减小;地震作用下,桥梁边墩的横桥向曲率大于中墩,矮墩的纵桥向曲率大于高墩,边墩的内肢墩较外肢墩更易遭受破坏。

To investigate the influence of free length of piles under high platform on seismic response of continuous rigid frame bridge with double thin-wall piers,finite element models were built based on a real bridge by the OpenSees program,and the elastoplastic time-history analysis was performed.By comparing the time-history curve,peak responses and hysteresis characteristics of bridges with different free length of piles,the influence of free length of piles on the bridges’seismic response was analyzed.The results show that the increase of free length of piles will reduce the stiffness of bridges.Under the earthquake,the displacement of main beam,bearing and the top of free piles increases with the increase of free length of piles,the increase of bearing displacement is greater than that of main beam and top of piles,and the internal force and deformation of pier bottom are reduced.The transverse curvature of side piers is greater than that of middle pier under the earthquake,the longitudinal curvature of low pier is greater than that of high pier,and the inner pier of bridge side piers is more vulnerable to damage than the outer piers.