纵向横系梁对双薄壁高低墩连续刚构桥抗震性能影响分析

Influence of Longitudinal Tie Beam on Seismic Performance of Continuous Rigid Frame Bridge with Slender Double-wall High and Low Piers

为研究纵向横系梁对双薄壁高低墩连续刚构桥抗震性能的影响,以跨径组合为58m＋100m＋58m的贵州省坞家塆大桥为工程背景,采用有限元软件Midas Civil建立全桥三维模型,通过时程分析法对不同横系梁设置数目、设置位置及不同刚度条件下,桥梁关键截面的地震响应进行分析。分析结果表明,纵向横系梁对结构纵向、竖向振动影响较大,横向振动无影响;随着横系梁设置数目增加,受力较大的薄壁墩弯矩显著减小,结构内力分配趋于合理,三道横系梁设置较优;低墩与高墩高度比值为0.75时,三道横系梁（上、中、下）的最优组合为0.3 H/0.5 H/0.7 H（H为桥墩高度）;当纵向横系梁与单肢薄壁墩刚度比在0.9-1.6时,桥墩结构受力是较为合理的。地震荷载下,纵向横系梁可作为耗能构件,保护主要桥墩结构,提高桥梁整体抗震性能。

In order to study the effect of longitudinal tie beam on the seismic performance of continuous rigid frame bridge with slender double-wall high and low piers,the Wujiawan Bridge with span layout of（58＋100＋58）m being the engineering background,the three-dimensional model of full bridge is built by using finite element software Midas Civil,the seismic responses of the key sections of the bridge are analyzed under the conditions of different tie beam number,location and rigidity by time-history method.The results show that：the longitudinal tie beam has a great influence on the longitudinal and vertical vibration of the structure,and the lateral vibration has no impact;with the increase of the number of the tie beam,the bending moment of the pier which has great inner force is significantly reduced,the internal force distribution of the structure is reasonable,and the three beam system is better;when the ratio between the low pier and the high pier is 0.75,the optimum combination of the three tie beam（top,middle,bottom）is 0.3H/0.5H/0.7H（H is the pier height）;when the stiffness ratio between the longitudinal tie beam and the single thin-walled pier is between 0.9 and 1.6,the force of the pier structure is reasonable.Under seismic loading,the longitudinal tie beam can be used as the energy dissipation component to protect the main pier structure and to improve the overall seismic performance of the bridge.