层间隔震结构减震机理的数值模拟分析

以振动台试验模型为背景,隔震垫采用铅芯橡胶隔震支座双线性滞回阻尼和粘滞阻尼的粘塑性分析模型,隔震层采用粘塑性分析模型,建立层间隔震结构的动力运动方程.同时,使用有限元分析软件ANSYS对该试验模型进行非线性有限元动力分析,获得层间隔震结构在地震动下的响应.分析结果表明,隔震层位置越低,隔震效果越好.随着隔震层设置位置下移,层间隔震体系在结构动力特性上体现为前两阶模态质量参与系数的比例发生变化.在中间层隔震区域,隔震层上部子结构反应基本上由一阶振型决定,而下部子结构反应却以二阶振型为主.隔震层上部子结构层间位移较稳定,可以近似为平动;下部子结构层间位移呈现抛物线状,且下部结构最大层间位移常出现在下部结构的中间位置.

Numerical simulation and analysis of damping mechanism of inter-storey anti-seismic structure

Taking a test model on shaking table as background,the lead-rubber antivibration bearings were used as isolation pad with bilinear hysteretic damping and visco-plastic damping in its analysis model.The visco-plastic analysis model was adopted for the isolation layer.Then the dynamic motion equations of inter-storey anti-seismic structure were established.Meanwhile,finite element analysis software ANSYS was used to carry out nonlinear finite element dynamic analysis for this test model.The responses of inter-storey isolation structure to seismic ground motion were obtained.The analysis result showed that the lower the location of the isolation layer was,the better the isolation effect would be.With the location of the isolation layer removing down,the proportion of the first two order modal mass participation factor of the inter-storey isolation system would change as its dynamic characteristics.In the isolation area of the middle storeys,the reaction of the upper substructure of the isolation layer was essentially determined by the first-order vibration mode,but the reaction of the lower substructure is mainly determined by the second-order mode.The inter-storey displacement of upper substructure above the isolation layer was more stable,which could be approximated as translational;the inter-storey displacement of the lower substructure exhibited a shape of parabola,and the maximum inter-storey displacement of the lower structure often occurred in its middle position.