纵向阻尼器对大跨度斜拉桥桥塔的抗震性能影响分析

Effect of longitudinal damper on seismic performance of long-span cable-stayed bridge tower

为确定大跨度斜拉桥在阻尼器抗震约束体系作用下的减震性能,文章以某大跨度斜拉桥为研究对象,采用通用有限元软件SAP2000建立全桥有限元模型,采用非线性时程分析方法,研究主塔在有、无阻尼器的情况下内力变化情况。研究结果表明:该桥动力特性分析表明,第1阶周期为7.821s,对应的振型为主梁纵漂+主塔纵向弯曲振动,远远大于结构的竖向、横向振动周期2.798、2.049s,抗震需求明显;设置纵向阻尼器的方式能有效地减小主塔在地震荷载作用下的内力,达到内力重新分布的目的,尤其是对弯矩的减小最为明显,从而改善结构的受力性能。

In order to determine the seismic performance of a long-span cable-stayed bridge under the seismic restraint system of dampers,this paper takes a long-span cable-stayed bridge as the research object,establishes the finite element model of the whole bridge by using the general finite element software SAP2000,and uses the non-linear time history analysis method to study the internal force variation of the main tower with or without dampers. The dynamic characteristics analysis of the bridge show that the first-order period is 7.821 s,and the corresponding mode of vibration is longitudinal drift of the main girder and longitudinal bending vibration of the main tower. It is much larger than the vertical and transverse vibration periods of 2.798 s and 2.049 s,and the seismic demand is obvious. It is shown that installing longitudinal dampers is an effective way to reduce the internal force of the main tower under seismic load and achieve the purpose of redistribution of the internal force,in particular for the reduction of bending moment,which can improve the mechanical performance of the structure.