隔震框架结构的Pushover方法分析

Pushover method analysis of isolation frame structure

Pushover分析作为结构抗震性能评估的静力非线性分析方法,可有效评估结构罕遇地震作用下的抗震性能。目前国内Pushover分析应用于抗震结构的研究较多,但用于隔震结构相对较少。本文先对高烈度区的5层和7层的框架结构,进行了分别采用倒三角和均匀加载方式的Pushover分析,并与非线性时程分析结果进行对比。针对相应的5层和7层隔震模型,进行了同样的对比分析。结果表明:对于抗震结构,Pushover方法的倒三角加载方式更合适;对于隔震结构,Pushover方法的均匀分布加载方式具有更高的精度。采用隔震设计后,结构层间位移和剪力大大降低,大震下上部结构基本弹性。对于隔震框架结构,采用均匀加载模式的Pushover分析在层间位移、隔震层位移等指标与非线性动力时程分析结果基本一致。推荐采用Pushover分析方法进行隔震框架结构抗震性能评估和优化设计。

As a simple and practical method to evaluate the seismic performance of structures,pushover analysis method can effectively evaluate the seismic performance under the action of rare earthquakes. At present,pushover analysis of conventional seismic structures has been widely used in China,but the research on isolated structures has not attracted sufficient attention. In this paper,the pushover and nonlinear time-history analysis results for the framework structure of 5 and 7 storey with two inverted triangle and uniform pushover loading modes are compared.Then the corresponding 5 and 7 storey isolation models are established for the same comparative analysis. The results show that the inverted triangular loading mode of Pushover method is more suitable for seismic structures,and the uniform distributed loading mode of Pushover method is more accurate for isolated structures. After the isolation design, the story drifts and shear force of the structure are effectively reduced,even after major earthquake,the superstructure is almost elastic. Pushover analysis of isolation structure with appropriate loading mode could have enough accuracy in the result of story drifts,isolation layer displacement and other indicators,compared with the results of nonlinear dynamic time history analysis. It is recommended to use Pushover analysis method to evaluate the performance of isolated structures or optimize the design.