极罕遇地震下大底板双塔楼PC隔震结构抗震性能分析

Seismic performance analysis of PC base-isolated double-tower structure with a large base floor under extremely rare earthquake

为研究极罕遇地震作用下大底板双塔楼PC隔震结构的抗震性能,采用ANSYS有限元软件对大底板双塔楼RC隔震结构和PC隔震结构进行了有限元模拟.对比分析了罕遇、极罕遇地震作用下两种结构的楼层位移响应、底板应力分布等动力响应和能量耗散情况.结果表明:相比RC结构,PC结构的自振周期和楼层位移响应增大,顶层加速度减小,上部结构塑性耗能增加,损伤严重;极罕遇地震作用下,两结构的隔震层变形显著增大,但耗能能力相对降低,上部结构耗能占比增大,建议在隔震设计时考虑使用较大直径隔震支座;极罕遇地震作用下,两结构塔楼连接位置处的大底板应力峰值均明显增大,故设计时应对塔楼连接位置采取相应的加强措施.

In order to study the seismic performance of PC base-isolated double-tower structure with a large base-floor under extremely rare earthquakes,the software ANSYS was used to carry out the finite element analysis of PC and RC base-isolated double-tower structure with a large base-floor.The floor displacement,base-floor stress distribution,other dynamic responses,and energy dissipation of the above two structures under rare and extremely rare earthquakes were compared and analyzed.The results show that compared with the RC structure,the natural vibration period and floor displacement response of the PC structure increase,while the top floor acceleration decreases.The plastic energy dissipation of the superstructure increases,and the damage is serious.Under the extremely rare earthquake,the isolation layer deformation of the two structures increases significantly,while the energy dissipation capacity decreases relatively,and the proportion of energy absorbed by the superstructure increases.Therefore,it is suggested that isolation bearing with a larger diameter should be considered in the isolation design as far as this situation is concerned.Under the extremely rare earthquake,the peak stress at the connection position of the two towers and the large base plate significantly increases,so corresponding strengthening measures should be taken in the design of the connection position of the towers.