不同高宽比基础隔震高层结构振动台试验研究及对比分析

摘要

Due to the development of isolation material and improvement of design concept and analysis method, the application of base isolation is extending to high-rise buildings with large aspect ratios.Shaking table tests were carried out to investigate the dynamic characteristics and seismic responses of high-rise base-isolated buildings with different aspect ratios when subjected to different earthquake records of various intensity.The comparison of dynamic characteristics between base-fixed and base-isolated buildings was performed simultaneously.A scaled 7-story steel frame was built as a specimen model and six lead-core laminated rubber bearings were selected as isolation devices.In tests,the aspcet ratio of model can be changed by shifting the bearings.The results of the shaking table tests convey that the natural periods of base-isolated models with aspect ratios 3,5 and 7,compared with that of base-fixed model,prolong from 0.267 s to 0.549 s,0.719 s and 0.8 s respectively.On the other hand,the maximum peak accelerations of top story under designed earthquake level decrease from 0.61g to 0.15g,0.16g and 0.18g.Moreover,it is found that the structural global drift angle increases and anti-overturning performance degenerates with the increase of aspect ratio.As a supplement,a three-dimensional finite element (FE)model was created and a good consistency between the results of FE analysis and test is observed.%为研究基础隔震高层结构的动力特性及地震响应规律，进行不同高宽比基础隔震高层结构在不同地震水准、不同地震激励下的模拟振动台试验，并与非隔震结构对比。模型采用缩尺7层钢框架结构，隔震支座用6件铅芯叠层橡胶支座，通过移动支座位置实现不同隔震高宽比。结果表明，高宽比为3、5、7基础隔震结构较非隔震结构自振周期从0．267 s 分别延长至0．549 s、0．719 s、0．800 s，设防地震作用下结构顶层最大加速度响应从0．61 g 减小至0．15 g、0．16 g、0．18 g。隔震后上部结构整体侧移角随高宽比增大而增大，结构整体抗倾覆性能随高宽比增大而减小。用三维实体有限元模型对试验进行数值模拟分析，试验结果与数值结果吻合较好，说明试验具有良好的准确性且可反映基础隔震结构的真实动力特性。