土与隔震结构共同作用的随机地震反应分析

采用子结构法,把地基土视为置刚性基础于其上的匀质、各向同性的粘弹性半空间,用Bouc-Wen光滑型滞变恢复力模型来模拟隔震层的弹塑性,上部结构采用剪切型结构模型建立土-结构动力相互作用的隔震结构非线性运动方程;利用状态空间法,将地震波以功率谱密度的形式输入,通过随机等效线性化获得隔震结构反应的统计值.分析表明,基于刚性地基假定的隔震结构设计并不总是保守的,地基土的类型和隔震结构的隔震度都在一定范围内对结构地震反应有显著影响.

Random Earthquake Responses of Base Isolation Structures Considering Soil-Structure Interaction

In this paper,the nonlinear equations of motion of the base isolation structures considering soil-structure interaction(SSI) are established by means of the substructure method.The soil is regarded as a uniform visco-elastic half space,and the hysteretic restoring force of isolation bearing is modeled by a smooth nonlinear differential equation(Bouc-Wen),and superstructure is a shear type of masses in series.By using the state space method,the ground acceleration is described through the power spectral density function,and the response statistics of structure are determined by equivalent linearization.The results imply that the design of base-isolated structure based on the rigid foundation is not always safe,and the characters of soil and degree of isolation can affect earthquake responses dramatically.