考虑地震动持时效应的结构拟静力试验加载制度研究

Study on loading protocol of structural quasi-static test considering strong motion duration effect

历次大地震震害表明,地震动持时对工程结构累积损伤有显著影响,长持时地震动作用下结构损伤明显加重,因此确定地震动持时对结构地震反应及损伤的定量影响成为近来一个热门研究课题。拟静力试验是模拟结构地震反应的重要手段,但目前其加载制度很少考虑地震动持时的影响。鉴于此,文中建立了7种周期、4种目标延性、2种本构模型共计56个单自由度体系结构,以114对长、短持时地震动为输入,计算了其位移反应时程,并通过雨流计数法统计分析了自振周期、目标延性及本构模型等参数和结构往复循环次数之间的关系。结果表明,结构非弹性循环圈数与周期和目标延性相关性较强,而结构振幅分布与周期相关性较小,但与目标延性相关性较强。根据统计结果拟合了不同周期结构在长持时地震动作用下的位移振幅分布公式,进而提出考虑地震动持时效应的结构拟静力试验加载制度确定方法,结果可供确定结构拟静力试验加载制度参考。

The earthquake damage investigation shows that the strong motion duration has significant effects on the cumulative damage of engineering structures,and the structural damage is more serious under the excitation of long duration ground motion.To determine the quantitative effect of strong motion duration on structural response and damage has been a hot research topic recently.The quasi-static test is one of the important means to simulate the seismic response of structures,but the loading protocol seldom considers the effects of strong motion duration in most cases.Therefore,a total of 56 single degree of freedom structural models with 7 periods,4 ductility levels and 2 hysteretic models are established in this paper,and the seismic displacement responses are computed under the excitation of 114 pairs of long and short duration ground motions.Then,the relationship between the number of reciprocating cycles and the natural period,target ductility,hysteretic model is statistically analyzed by the rain flow cycle counting algorithm.The results show that the number of inelastic reciprocating cycles of the structure has a strong correlation with the structural period and target ductility,while the displacement amplitude distribution has a weak correlation with the structural period,but has a strong correlation with the target ductility.According to the results,the displacement amplitude distribution equation of structures with different periods under long duration ground motion are fitted and obtained,then the method of formulating the structural quasi-static test loading protocol is proposed to consider duration effect.The results and conclusions can be used for structural quasi-static test.