三维远场长周期地震下考虑SSI层间隔震结构地震响应分析

Seismic response analysis of inter-story isolation structures considering SSI under three-dimensional far-field long-period ground motions

实际地震具有多维特性,只考虑水平向作用往往不够真实全面,而且远场长周期地震动不同于普通地震动,具有周期长、持时长、低频成份丰富等特征,对周期较大的隔震类结构会产生不利影响,在考虑SSI效应(soil-structure interaction,SSI)中尤为复杂,需深入探讨。基于此,建立大底盘层间隔震结构,在三维地震动激励下,探讨普通地震与远场长周期地震对层间隔震结构的不同影响,并分析考虑SSI效应对结构的不同程度影响。结果表明:三维地震下,远场长周期对层间隔震结构产生的地震响应远大于普通地震;考虑SSI效应时,随着土体变软,结构响应增大;针对传统水平隔震支座,在三维远场长周期地震下出现层间位移角和支座位移超限问题,设置三维隔震支座,解决了超限问题,分析结果表明其隔减震效果明显优于传统水平隔震支座。

Earthquake excitation is a kind of complicated multi-dimensional motion,so it is not safe and accurate enough to only consider horizontal earthquake excitation.Unlike ordinary ground motions,far-field long-period ground motions have characteristics such as long period,long duration,and rich low-frequency components.They will have adverse effects on structures with large isolation periods.The soil-structure interaction(SSI)is particularly complicated and needs further discussion.Therefore,a large chassis inter-story isolation structure was established in this paper.Under the excitation of three-dimensional ground motion,the different effects of ordinary earthquakes and far-field long-period earthquakes on the inter-story isolation structure were discussed,and the different effects of SSI on the structure were analyzed.The results show that the seismic response of three-dimensional long-period far-field ground motion on the inter-story isolated structure is far greater than that of ordinary ground motion.When the SSI effect is considered,the structural response increases with increasing soil softness.Three-dimensional isolation bearings were set to solve the problems of traditional horizontal isolation bearing under three-dimensional far-field long-period ground motion,i.e.,story drift ratio and bearing displacement beyond limits.The analysis results show that the isolation effect of three-dimensional isolation bearings is better than that of traditional horizontal isolation bearings.