近断层脉冲地震作用下偏心基础隔震结构的地震反应研究

RESEARCH ON SEISMIC RESPONSE OF ASYMMETRIC BASE-ISOLATED STRUCTURES UNDER NEAR-FAULT PULSE-LIKE GROUND MOTIONS

建立了考虑每个隔震支座变形的偏心基础隔震结构层间剪切模型,提出了合成双向近断层脉冲地震的方法;以此作为输入,对比研究了偏心基础隔震结构在双向近断层脉冲地震和远场地震作用下的非线性地震反应,分析了隔震层偏心、上部结构偏心、上部结构转侧频率比以及近断层脉冲地震脉冲周期等参数对于偏心基础隔震结构地震反应的影响。研究表明:存在隔震层偏心使偏心基础隔震结构对近断层脉冲地震作用更加敏感,并且近断层脉冲地震的脉冲周期对偏心隔震结构在近断层脉冲地震作用下的反应有很大的影响。

In this paper, inter-story shear model of the asymmetric base-isolated structure is built, which incorporates the deformation of each isolation bearing. And a methodology is developed to simulate simultaneously bi-axial near-fault pulse-like and far-field ground motions, Under both near-fault pulse-like and far field ground motions, the nonlinear dynamic responses of the asymmetric base-isolated structure are investigated comparatively. Seismic responses are closely related with isolation eccentricity, superstructure eccentricity, ratio of torsional-to-lateral frequency of superstructure, and pulse period of near-fault pulse-like ground motions, whose effects are discussed in this paper. Results show that the asymmetric base-isolated structure with isolation eccentricity is more vulnerable to near-fault pulse-like ground motions, and its seismic response is mainly governed by the pulse period of near-fault pulse-like ground motions.