LRB基础隔震结构在极罕遇地震作用下的碰撞响应研究

Impacts of LRB Base Isolation Structure Under Extremely Rare Earthquakes

随着极罕遇地震作用的引入,有必要探讨基础隔震结构在极罕遇地震作用下是否还具有良好的抗震性能。采用改进的Kelvin碰撞分析模型和双线性恢复力模型,建立基础隔震结构与周围挡土墙碰撞的运动方程,用MATLAB进行非线性时程分析。基于非线性时程分析的结果,研究基础隔震结构在极罕遇地震作用下的碰撞响应。比较考虑碰撞和不考虑碰撞两种情况下,上部结构平均延性系数和隔震支座平均剪应变随隔震结构力学性能参数的变化曲线;不同碰撞参数下,上部结构平均延性系数和隔震支座平均剪应变随隔震结构力学性能参数的变化曲线。结果表明基础隔震结构在极罕遇地震作用下的碰撞控制了隔震支座的剪应变,但加剧了上部结构的动力响应。提高上部结构或者隔震体系的屈服承载力可以降低上部结构的碰撞响应,增加隔震缝宽度、提高隔震体系屈服承载力或者隔震支座直径可以降低碰撞发生的概率。

Considering extremely rare earthquakes,it is necessary to explore whether the foundation isolation structure still has good seismic performance under extremely rare earthquakes.Using the improved Kelvin collision analysis model and bilinear restoring force model,the motion equation of the collision between the foundation isolation structure and the surrounding retaining wall is established,and MATLAB is used for nonlinear time history analysis.Based on the results of nonlinear time history analysis,the impact response of foundation isolation structures under extremely rare earthquakes is analyzed.Comparing the curves of the average ductility coefficient of the superstructure and the average shear strain of the isolation bearing with the mechanical performance parameters of the isolation structure under different collision parameters with and without considering the collision.The variation curve of the average shear strain of the seat with the mechanical performance parameters of the isolated structure.The results show that the collision of the base isolation structure under the action of the rare earthquake controls the shear strain of the isolation bearing,but aggravates the dynamic response of the superstructure.Increasing the yield bearing capacity of the superstructure or the isolation system can reduce the collision response of the superstructure,and increasing the width of the isolation joint,increasing the yield bearing capacity of the isolation system or the diameter of the isolation bearing can reduce the probability of collision.