考虑SSI效应及支座转动的隔震体系性能研究

Performance research on seismic isolated structure considering soil-structure interaction and rotation of isolation layer

土-结构相互作用对结构的地震反应有着重要的影响。隔震支座竖向变形引起的隔震层转动会加剧上部结构的摇摆,进而放大结构的地震响应。提出基于Timoshenko理论的考虑SSI效应及隔震层转动影响的隔震结构通用计算模型,推导并求解结构运动方程,采用虚拟激励法进行随机响应分析,进一步研究隔震层转动刚度、土体参数等对隔震结构地震响应的影响规律。分析表明:SSI效应降低了隔震效果,其对隔震结构楼层转角位移放大的影响与土-结构刚度比有关。隔震层转动刚度变化对隔震结构顶层加速度、基底倾覆力矩等影响较小,但对结构楼层转角位移有较大影响,隔震层转动刚度取值较小时,上部结构楼层转角甚至会出现大于抗震结构的情况。

Soil-structure interaction has important influence on the seismic response of the structure. The rotation of isolation layer caused by vertical deformation of isolation bearing can increase the swing of upper structure,and then the seismic response of structure is enlarged. The calculation model involving SSI effect and rotation of isolation layer is developed based on Timoshenko theory. The equations of motion are formulated. Pseudo excitation method is used in seismic random response calculating. The influences of the rotation stiffness and soil parameters on the seismic response of isolated structures are discussed. Further analysis indicates that SSI affected the isolation effectiveness and the amplification factor on angular displacement of isolated structure is related to the ratio of soil-structure stiffness. The influence of isolation layer rotation stiffness on top acceleration and base overturning moment are not distinct. The vibration of isolation layer rotation stiffness has a great influence on the rotation angle of upper structure. When the rotational stiffness of isolation layer is relatively small,the angular displacement of upper structure is even larger than that of seismic structure.