高层隔震结构在长周期地震动作用下的响应分析  

Structural Response of High-rise Base-isolated Buildings under the Action of Long-period Ground Motions

作　　者：赵益彬[1] 吕西林[1] 

机构地区：[1]同济大学结构工程与防灾研究所,上海200092

出　　处：《结构工程师》2016年第3期77-85,共9页Structural Engineers

摘　　要：将地震波进行经验模态分解（EMD）求得固有模态函数（IMF）并做希尔伯特一黄变换，求得地震动记录的累积能量谱以及边际谱。通过边际谱的平均特征周期或口谱2～10S的加权平均值的定量方式区分出普通地震动和长周期地震动。为了考察高层隔震结构在长周期地震作用下的响应，建立一有实际工程背景的基础隔震的高层建筑模型；输入经过长周期地震波和反应谱与规范反应谱相符的地震波进行时程分析，比较两者作用下结构响应的异同。分析结果表明：定量的方式可以区分长周期地震动和普通地震动，将经过区分的长周期地震波作为输入，算例在长周期多遇地震及罕遇地震作用下，底部固定高层结构和高层隔震结构的楼层剪力平均值、层间位移角以及高层隔震结构的隔震层位移均较与反应谱相符的地震作用下大，隔震层位移的增大尤其明显。从隔震系数和层间位移角而言，长周期地震作用下的隔震效果较差。符合规范反应谱的时程分析表明该高层隔震结构本身隔震性能良好，上部结构性能接近大震弹性。因此高层隔震结构在等值PGA的输入下，长周期地震作用下，高层隔震结构在小震和大震下都很难满足设计要求，对于存在长周期地震动风险的情况下，需要开发适合于高层隔震结构的隔震体系。同时，拟输入地震动为长周期地震动时，等值PGA不是一个合理的指标。Selected earthquake waveswere decomposed into intrinsic mode function （IMF） by using empirical mode decomposition （EMD） and IMF were transformed by using Hilbert-Huang transform so that cumulative energy spectrum and marginal spectrum can be obtained. The average characteristic period of marginal spectrum along with weighted average value of spectrum can be used as a tool to differentiate long-period ground motion record from the ordinary records. An engineering based model is made to analysis the response of high-rise isolated building. Selected ground motions are inputted to find out the difference between the response under the action of long-period ground motion and normal ground motion. The results show that quantitative measures in the article can distinguish long-period ground motions from ordinary one. Long-period waves distinguished were used as input in analysis. Under the action of long-period ground motions, average storey shear, inter-storeydrift angle of fixed base structure and base isolated structure and displacement of isolation layer of base-isolated building is larger than that of under the action of ground motions fitted with code; especially for the displacement of isolation layer. From the prospective of earthquake reduction coefficient and inter-storeydrift angle, long-period ground motions cause worse effect of isolation. In the time history analysis fitted with code specified response spectrum, the high-rise base-isolated structure performedwell whose upper structure almost remain elastic when earthquake with rare intensity was applied. Consequently, in the analysis with same PGA, the response of high-rise base isolated structure under long- period ground motion is hard to satisfy the requirement of code. For the structure that under the threat of long- period ground motion, it is required to develop isolation system suitable for high-rise base-isolated buildings. Meanwhile, when using long-period ground motions as input, same PGA is not a good criteria.

关 键 词：长周期地震动 高层隔震结构 时程分析 

分 类 号：TU973.31[建筑科学—结构工程] TU352.12