不同场地及地震输入下的土-框架结构相互作用体系地震反应分析

Seismic response analysis of frame structures considering soil-structure dynamic interaction

为了研究框架结构在不同场地及不同地震波输入的地震反应,本文建立了土-结构相互作用(SSI)体系有限元模型。对模型进行了模态分析及时程分析,得出以下结论:土-结构相互作用体系的结构频率低于框架结构自振频率,土层刚度越低,结构频率越低。不同波速的场地对地震波的放大效应不同,刚度较大的场地土对低频有明显的过滤作用。场地基频小于结构一阶频率时,结构振动以一阶振型为主。场地基频大于结构一阶频率时,结构峰值加速度沿高度分布与输入地震波相关。框架结构层间位移角大小的变化是由场地频率与输入地震波频谱特性共同决定的。

In order to study the seismic response of frame structures in different stiffness sites and different seismic wave inputs,the model of soil-structure interaction(SSI)system is established.The modal analysis and time history analysis of the model are carried out.The results indicate that the structural frequency of SSI system is lower than that of frame structure,and the structural frequency decreases with the decrease of soil stiffness.The site soil has different amplification effect on seismic wave with different seismic velocity.The site with higher stiffness has obvious filtering effect on low frequency.When the site fundamental frequency is less than the first-order frequency of the structure,the first-order vibration mode is dominant.When the site fundamental frequency is greater than the first-order frequency of the structure,the distribution of the peak acceleration along the height of the structure is related to the input waves.The change of the inter story displacement angle of frame structure is determined by the site frequency and the spectrum characteristics of input seismic wave.