极罕遇地震作用下隔震结构碰撞响应与隔离缝宽度研究

Study on pounding response and width of isolation joint of isolated structure under extreme rare earthquakes

以上部结构分别为3、5、7、9层的LRB(铅芯橡胶隔震支座)基础隔震结构为研究对象,通过大量的弹塑性时程分析,对罕遇和极罕遇地震作用下基础隔震结构无碰撞、与限位墙以及与相邻基础固定结构发生碰撞时的地震响应、隔离缝宽度等进行了研究和对比分析。结果表明,在极罕遇地震作用下,对于上部结构屈服强度比一定、刚度在一定范围内变化的LRB基础隔震结构,会与相邻结构发生碰撞并且上部结构的破坏程度差异很大;当允许基础隔震结构与限位墙或与基础固定结构发生碰撞,上部结构进入一定的塑性状态且具有相同的延性需求时,上部结构刚度较大的基础隔震结构反而需要较大的隔离缝宽度;随着基础隔震结构以及相邻基础固定结构楼层数的增加,避免碰撞所需的隔离缝宽度逐渐增大。

This study focuses on the LRB(lead rubber bearing)base-isolated structures with three-story,five-story,seven-story,and nine-story superstructures as research objects.Through a large number of elastic-plastic time-history analysis,the seismic response and width of isolation joint under the conditions of no pounding,pounding with the limit wall,and pounding with the adjacent fixed structure under rare and extreme rare earthquakes are studied and compared.It is shown that under extreme rare earthquakes,the LRB base-isolated structures which the yield strength ratio of superstructure is certain and stiffness of the superstructure changes within a certain range may collide with the adjacent structures,and the damage degree of the superstructures is very different.When the pounding between the base-isolated structure and the limit wall or the base-fixed structure is allowed,and the superstructure enters a certain plastic state and has the same ductility demand,the LRB base-isolated structure with fewer floors and larger stiffness of the superstructure needs a larger width of isolation joint.With the increase of the number of floors of adjacent structures,the width of isolation joint needed to avoid pounding increases.