弹塑性MDOF系统地震输入能量研究

基于地震作用下弹塑性SDOF(Single Degree of Freedom)和弹性MDOF(Multi-degree of Freedom)系统能量输入研究,本文分析了弹塑性MDOF系统能量输入规律。以实测地震记录为输入,采用弹塑性时程分析方法,计算了一阶初始周期≤3s的5、10、20、30层双线性滞回剪切层模型,不同阻尼比、承载力降低系数情况下4800个结构和一阶初始周期>3s的40层结构能量输入,与弹塑性SDOF系统的输入能量谱进行对比。研究表明:一阶周期在3s以内的弹塑性MDOF系统输入能量EI可用相同阻尼比、初始周期、承载力降低系数的弹塑性SDOF系统计算结果近似确定;一阶周期大于3s的弹塑性MDOF系统,可采用MPA方法等效为多个弹塑性SDOF系统,按照振型叠加法计算总输入能。

Earthquake Energy Input of Inelastic MDOF Systems

Based on the study of the input energy spectra of inelastic SDOF(Single Degree of Freedom) systems and the input energy elastic MDOF(Multi degree of Freedom) system,the calculation method of input energy of inelastic MDOF system is studied in this paper.With nonlinear time history analysis method using the ground motion records,4800 cases with the first mode period less than 3 second and one 40-stories case with the first mode period larger than 3 second are analyzed to obtain their input energy and are compared with the corresponding inelastic SDOF systems with the same first mode period,damping ratio and strength reduction factor.The results show that the input energy of inelastic MDOF system with the first mode period less than 3 second can be obtained based on spectra of the corresponding inelastic SDOF system with the same first mode period,damping ratio and strength reduction factor,while for the inelastic MDOF system with the first mode period larger than 3 second,the input energy can be obtained on the basis of MPA method.