考虑SSI效应的层间隔震结构自振特性及随机响应分析

Natural vibration characteristics and the stochastic response of inter-story isolation structures considering the SSI effect

基于水平摇摆阻尼系统模型,建立土-层间隔震结构简化分析模型,将地基土等效到上部结构,推导得到简化模型动力特性参数表达式,并通过对结构周期比及振型参与位移进行分析,讨论质量比及土体剪切波速对层间隔震结构自振特性的影响规律。利用虚拟激励法及均匀调制非平稳随机响应分析方法,分别从时域和频域角度分析不同场地条件下SSI效应对层间隔震结构的振动响应影响。结果表明:在刚性地基下,结构质量比对结构周期比及振型参与位移的影响较小,SSI效应放大了各子结构响应,尤其对下部子结构响应影响最大,各子结构在场地土差异下变化明显,软土场地下各子结构响应变大。

A simplified analysis model of a soil-inter-story isolation structure was established in this paper based on the lateral-rocking damping system model.The foundation soil was equivalent to the superstructure,and then the expression for dynamic characteristic parameters of the simplified model was derived.The influence of the mass ratio and shear wave velocity of soil on the natural vibration characteristics of the inter-story isolation structure was discussed by analyzing the period ratio and modal participation displacement.Then,the influence of the soil-structure interaction(SSI)effect on the vibration response of inter-story isolation structures under different site conditions was analyzed in the time and frequency domains using virtual excitation and nonuniformly modulated nonstationary random response analysis,respectively.Results show that the structural mass ratio has little effect on the period ratio and modal participation displacement of the structure on a rigid foundation.The SSI effect enlarges the response of each substructure,particularly the response of the lower substructure.The response of each substructure changes significantly with different soil sites,and it increases in soft soil sites.