水平初位移条件下实际隔震结构现场测试

Field Test for A Base Isolation Structure Under the Condition of Horizontal and Initial Displacement

已建成的隔震建筑仅有小部分经受过地震考验,由被动控制特点可知,隔震层的动力特性缺乏跟踪调节和控制能力。现场测试了1栋基础隔震幼儿园建筑,检验实际隔震结构的动力特性和抗震性能。隔震层由20个LNR500和26个LRB400橡胶支座组成,测试了水平初位移75 mm(LRB400的109%剪应变)条件下的动力特性,展示了实现水平位移条件的方法及试验所得主要结果。水平位移的实现通过混凝土反力墙、顶杆及液压泵系统配合完成,将建筑推开位移,顶杆爆破卸载使建筑做自由振动。试验结果表明:隔震结构的自振周期比抗震结构显著延长;隔震层滞回曲线饱满;顶杆卸载后隔震层瞬间基本复位,残余变形在48 h内逐渐消除;各楼层动力响应控制效果明显,顶层加速度约放大1.27倍。

Only a few isolated structures have been subjected to the test of earthquakes,due to the technical characteristics of passive control,isolation layer lack the ability of instantaneous adjustment and control. The field testing has been conducted on a kindergarten building with base isolation to analyze the dynamic characteristics and seismic performance of the actual isolated structures. This isolation layer is composed of 20 LNR and 26 LRB,its dynamic characteristics has been tested under the conditions of 75 mm horizontal initial displacement（ 109% shear strain of LRB400）. From the test,the method of achieving horizontal displacement conditions was demonstrated and the main test results were obtained. Horizontal displacement conditions were achieved by combining the joint force of concrete reaction wall,mandrel and hydraulic pump design system. First,the construction was pushed to the designed displacement of 75 mm,and then the mandrel was instantaneously burst and uninstalled to put the construction to the state of one- time one- way free vibration. The results showed that the vibration period of the isolation structure was significantly longer than the seismic structure; isolation layer hysteretic curve was full; isolation layer substantially instantaneously reset after mandrel uninstalling,residual deformation gradually eliminated within 48h; dynamic response damping effect of each floor was noticeable,acceleration responses at the top floor magnified approximately 1. 27 times.