脉冲型非一致地震作用下千米级斜拉桥减震研究

Research on the seismic reduction of cable-stayed bridges over kilometers under pulse-type non-uniform earthquake action

首先考虑场地和视波速等因素,从已知脉冲型地震动合成相关点的脉冲型非一致地震动;其次建立了千米级斜拉桥有限元模型,进行了非一致地震反应分析,考虑了几何非线性,结果表明混合场地以及较低的视波速为该类型桥梁的最不利工况;然后对弹性连接和黏滞阻尼器2种减震方式进行了参数分析;最后对2种方式的减震效果进行了比较,结果表明:黏滞阻尼器在脉冲非一致地震动下的减震效果不如在一致地震动输入情况下的明显,对塔底弯矩的减震效果甚至不如弹性连接方式。修建更大跨径的斜拉桥,其脉冲非一致地震动下的减震设计,可能需要另寻它法。

Firstly,the pulse type non-uniform ground motions at related position were synthesized from the recorded pulse ground motions with the factors of ground condition and apparent wave velocity were considered. Secondly,the finite element model of a cable-stayed bridge over kilometers was built; the geometric nonlinearity was taken into account; the non-uniform seismic response analysis was conducted,and the results show that the mixed ground condition and lower apparent wave velocity is the most unfavorable conditions for this kind bridge. Thirdly,parameters analyses were conducted on the elastic connections and viscous dampers devices. Lastly,seismic reduction efficacy of the two devices were compared,and the results show that the viscous dampers under the non-uniform ground motion is poor than that under the uniform ground motion,and its reduction efficacy of bending moment at the tower bottom is even poor than that of elastic connection device. When building longer span cable-stayed bridge,the seismic reduction design under pulse type non-uniform ground motion may need to find another method.