基于试验的串联隔震体系非线性力学性能有限元分析

Finite element analysis of nonlinear mechanical behavior of series seismic isolation system based on tests

为研究由铅芯橡胶支座(LRB)和钢筋混凝土(RC)柱组成的串联隔震体系(SIS)的非线性力学性能,以LRB的试验和SIS的振动台试验为基础,建立8组带LRB的SIS模型。首先用有限元软件MARC对LRB进行分析,LRB的等效刚度和滞回曲线与试验结果基本一致。在此基础上,对8组SIS模型进行Pushover分析和不同幅值的循环荷载分析,研究SIS的力和位移曲线、特征承载力、刚度、阻尼比和破坏特点,分析RC柱的高宽比对SIS的特征承载力、刚度、阻尼比和破坏形式等力学性能的影响,并对比SIS等效刚度的有限元分析结果和试验分析结果,变化趋势基本一致。结果表明,SIS的非线性力学性能受LRB力学性能影响较为明显,而当高宽比大于4时,RC柱对SIS的力学性能随着高宽比的增大影响逐渐增大,建议柱高宽比损伤限值3.5(含3.5)和安全限值5,为结构设计提供参考依据。

In order to study the nonlinear mechanical behavior of series Seismic Isolation System（ SIS） composed of lead-rubber bearing（ LRB） and reinforcement concrete（ RC） column,8 groups of SIS finite element（ FE） models with LRB were established based on the LRB test and shaking table test of SIS. Firstly,LRB was analyzed using the FE software MARC,and numerical results show that the achieved equivalent stiffness and hysteretic curves are basically identical to the LRB test results. Secondly,8 groups of SIS models were analyzed with Pushover method and under cyclic loads with different amplitude for the nonlinear mechanical behaviors of SIS,including the relationship curve of force and deformation,characteristic bearing capacity,stiffness,damping ratio and damage characteristics. Then,the effects of aspect ratio of RC column on these mechanical behaviors of SIS were investigated. Finally,the equivalent stiffness from the FEA analysis was compared with that of SIS test,the trends are basically consistent. The results indicate that nonlinear mechanical behaviors of LRB have obvious influences on those of SIS,and the effects of RC column on nonlinear mechanical behaviors of SIS may increase with increasing the aspect ratio of RC column when it is larger than4. As a result,the damage limit value and safety limit value for aspect ratio of RC column are suggested to be 3. 5 and5,respectively,which offers reference for structure design.