中等跨径斜拉桥塔梁弹性约束装置的减震效应研究

Research on the seismic performance of mid-span cable-stayed bridges with elastic constraints between tower and beam

对于高烈度设防区的中等跨径斜拉桥,往往采用漂浮或半漂浮体系结构,为防止梁端位移过大,需在桥塔和主梁之间设置合理的弹性索约束。为了得到合理的弹性索刚度值,以一座中等跨径混凝土斜拉桥为例,首先推导了塔、梁之间弹性约束刚度值的估算公式,并建立桥梁的动力分析模型,利用反应谱方法分析了弹性约束装置刚度参数变化对桥梁动力特性、索塔内力和塔顶、梁端位移的影响规律,通过参数分析得到了与公式计算值相吻合的最优解。分析结果表明:本文的弹性索刚度估算公式可以较准确估算弹性索的刚度初始值;弹性索能有效地控制漂浮、半漂浮体系斜拉桥过大的梁端位移,并改善斜拉桥索塔的受力状况。

The floating and half-floating cable-stayed bridges are often designed in the zones with high seismic fortification intensity. However, in order to control the excessive displacement of girder, we used to set the elastic constraints or dampers between tower and beam. Based on a medium span concrete cable-stayed bridge, this paper proposes the reasonable elastic constraints, and presents the computing method of the elastic stiffness. Then, thedynamic analysis model of the example bridge is built and the response spectrum is used to analyze the effect on dynamic characteristics, the internal force of the tower and the girder displacement due to the varying of stiffness ofelastic constraints. The parametric analysis is adopted to obtain the optimum value, which is coincident perfectly with the computing result. It has been observed that the computing method of the elastic stiffness in this paper canestimate the initial stiffness well, in other words, this stiffness can not only improve the seismic performance but also control the girder displacement in an appropriate range.