罕遇地震下大跨隔震结构随机地震响应

Random Seismic Response Analysis of Large Span Isolated Structures Subjected to Rare Earthquake

为研究大跨隔震结构在多维多点地震输入下的复杂性态,首先人工合成了同时考虑地震动场空间相关性和非平稳特性的多维多点随机加速度时程,然后采用绝对位移输入法计算多维多点和多维一致激励下大跨隔震网架结构地震反应,最后以结构跨度、视波速为主要变量系统地研究两种地震动输入模式下大跨隔震结构网架屋盖水平向和竖向地震反应的差异。结果表明:大跨隔震结构多点输入效应随着视波速的增大逐渐减弱,当视波速达到500 m/s之后可忽略,即得到“界限视波速”;多点输入效应随着跨度的增大而增强,得到可以忽略和必须考虑多点输入效应的“界限跨度”分别为60 m和120 m;水平变形隔震效果随着结构跨度的增大呈现出整体变好的趋势,没有明显的竖向隔震效果;大跨隔震结构网架屋盖周边支座附近响应较大,易出现隔震后响应较大的情况,在工程设计时应予以需要加强。

In order to study the complex behavior of large span isolated structures under multi-dimensional and multi-point earthquake input,the multi-dimensional and multi-point random acceleration time histories considering the spatial correlation and non-stationary characteristics of the ground motion field are synthesized artificially,and then the absolute displacement input method is used to calculate the seismic response of large span isolated grid structures under the multi-dimensional and multi-point excitation or the multi-dimensional and uniform excitation.At last,the structural span and apparent wave velocity are taken as the main variables to investigate the difference of horizontal and vertical seismic responses of the truss roof of the large span isolated structures under two seismic input modes systematically.The results show that the multi-point input effect of large span isolated structures weakens reduces with the increase of apparent wave velocity.When the apparent velocity of a seismic wave reaches 500 m/s,the multi-point input effect can be neglected,that is,its boundary value is obtained.The multi-point input effect strengthens gradually with the increase of the span,and the boundary values of the span to ignore or consider this effect are 60 m and 120 m respectively.With the increase of structural span,the isolation effect of horizontal deformation of structures shows a tendency to be better,and there is no obvious vertical isolation effect.Those nodes near the boundary supports of the large span truss roof show greater responses after the isolation,which need be strengthened in the engineering design.