矩形脉冲激励下高层隔震结构提离摇摆界限谱模型及参数影响分析

Dynamic model and parametric analysis of high-rise isolation structure under rectangular pulse excitation

判别高层结构所处的摇摆状态是分析地震作用时隔震层是否处于安全状态以及结构是否处于稳定状态的重要基础。根据隔震层橡胶支座的竖向变形计算结果,将高层隔震结构的摇摆状态分为未提离、提离、摇摆、倾覆状态,提出了基于简化刚体模型的提离摇摆状态分类方法。通过分析矩形激励下竖向屈重比、水平屈重比、竖向周期、水平周期、高宽比、激励幅值系数、激励频率比等参数对高层隔震结构摇摆响应的影响,得到了高层隔震结构未提离、提离、摇摆的界限谱以及主要参数对界限谱的影响规律,进一步分析了高层隔震结构倾覆状态与激励幅值、频率比之间的关系。研究结果表明:摇摆响应随竖向屈重比、水平屈重比、激励频率比的增大而减小,其中水平屈重比的影响最大;摇摆响应随激励幅值系数、竖向周期、水平周期及高宽比的增大而增大,摇摆响应较小时高宽比的影响最大,摇摆响应较大时竖向周期的影响最大,控制摇摆响应的最有利措施是增大水平屈重比、减小高宽比和竖向周期;对提离界限影响程度从大到小的顺序为高宽比、水平屈重比、竖向周期、竖向屈重比、水平周期,对摇摆界限影响程度从大到小依次为竖向周期、水平屈重比、高宽比、水平周期、竖向屈重比;结构倾覆与激励幅值系数、激励输入时间呈正相关。

The determination of rocking state for a high-rise structure is a fundamental issue to estimate whether the isolated layer is safe under seismic excitation.In this study,by using the tensile deformations at the vertical direction of the rubber support,the rocking states of a high-rise structure were divided into ones with unuplifting,in uplifting,in rocking and in overturning,and a classification method was then proposed for estimating the rocking state.Inspired by the influences of the vertical yield-weight ratio,horizontal yield-weight ratio,vertical cycle,horizontal cycle,aspect ratio,excitation amplitude coefficient,excitation frequency ratio on the swing response of high-rise isolated structures under rectangular excitation,boundary spectrum of high-rise isolation structures and the relationship between the overturning state of high-rise isolation structure,excitation amplitude coefficient and excitation frequency ratio were achieved.It shows that swing response decreases with the increase of vertical yield-weight ratio,horizontal yield-weight ratio and excitation frequency ratio,where the effect of horizontal yield-weight ratio is the most significant.Swing response increases with the increase of excitation amplitude coefficient,vertical cycle,horizontal cycle and aspect ratio.When swing response is small,the effect of aspect ratio is the most significant,otherwise,the effect of vertical cycle is the most significant.And the most advantageous measure to control the swing response is increasing the horizontal yield-weight ratio,or decreasing aspect ratio and vertical cycle.The great-small influence degree on boundary of unuplifting and uplifting is aspect ratio,horizontal yield-weight ratio,vertical cycle,vertical yield-weight ratio,horizontal cycle.The great-small influence degree on boundary of uplifting and rocking is vertical cycle,horizontal yield-weight ratio,aspect ratio,horizontal cycle,vertical yield-weight ratio.The structure overturning is proportional to excitation amplitude coefficient and excitation input time.