考虑SSI效应的层间隔震与基础隔震结构地震响应对比分析

Comparative analysis of seismic response of story isolation and base isolation structures considering SSI effect

为探究不同地基上的层间隔震和基础隔震结构在考虑SSI效应后的地震响应差异,选取一个适合采用隔震技术的规则结构,以5层缩尺的规则结构模型进行振动台试验,探究结构在刚性地基、硬土(vs=300m/s)与软土(vs=80m/s)地基上结构动力特性与地震响应。结果表明:对于模型,考虑SSI效应时基础隔震结构隔震效果优于层间隔震结构;土性地基上层间隔震结构和基础隔震结构自振周期较刚性地基上延长;地基土体对地震波存在明显的放大作用和滤波效应,软土地基能明显增强地震波中的低频成份、过滤高频成份;对比分析揭示了土性地基上隔震结构,层间隔震体系下部结构的位移响应在考虑SSI效应时显著放大,在工程应用中应予以着重考虑。

In order to explore the difference of seismic response of story isolation and base isolation structures on different foundations after considering SSI effect,a regular structure suitable for isolation technology is selected.Shaking table test is carried out on a 5-layer scale regular structure model to explore the dynamic characteristics and seismic response of the structure on rigid foundation,hard soil(v s=300m/s)and soft soil(v s=80m/s).The results show that for the model,the isolation effect of the base-isolated structure is better than that of the story-isolated structure when considering the SSI effect;the natural vibration period of the upper isolation structure and the base isolation structure on the soil foundation is longer than that on the rigid foundation.The foundation soil has obvious amplification and filtering effect on the seismic wave.The soft soil foundation can obviously enhance the low frequency component and filter the high frequency component in the seismic wave.The comparative analysis reveals that the displacement response of the lower structure of the isolation structure on the soil foundation is significantly enlarged when considering the SSI effect,which should be considered in engineering applications.