考虑周期折减的结构弹性时程分析调整方法

Adjustment method for elastic time-history analysisof structures considering period reduction

针对结构弹性时程分析时无法考虑周期折减的问题展开研究,通过对比结构时程分析的过程中,地震波的选取是否考虑周期折减的差异,提出采用增大系数放大时程分析法输入地震波有效峰值加速度以及地震响应;考虑弹性时程分析过程中,周期折减对结构地震作用的增大效应。理论分析增大系数取值的影响因素,并基于单自由度体系对比两种调整方法的效果及差异,采用实际算例以验证所提出弹性时程分析中考虑周期折减调整方法的有效性。结果表明:增大系数的取值与周期折减系数、结构自振周期及场地特征周期等因素有关;对于单自由度体系,两种调整方法具有完全相同的调整效果;按文章提出方法考虑周期折减的算例结构,弹性时程分析所得各楼层地震剪力及层间位移角与考虑周期折减的反应谱(CQC)计算结果均较为接近。

The problem that the period reduction cannot be considered in a structural time-history analysis was studied.Structural time-history analyses considering and neglecting the period reduction were compared,and then the amplification coefficient was proposed to amplify the effective peak acceleration of the input ground motion and the seismic response in time-history analysis to consider the amplification effect of period reduction on the structural seismic response in elastic time-history analysis.The influences of involved parameters on the amplification coefficient were studied theoretically.Then,the adjustment effects and differences between the two adjustment methods were compared on the basis of the single-degree-of-freedom system.Moreover,an engineering example was used to verify the effectiveness of the proposed methods considering period reduction in the elastic time-history analysis.The results show that the value of the amplification coefficient is related to the period reduction coefficient,the natural vibration period of the structure,and the characteristic period of the site.For the single-degree-of-freedom system,the two adjustment methods have identical adjustment effects.The seismic shear force and story drift ratio of each floor of the example structure obtained using the elastic time-history analysis are near those calculated by the response spectrum considering the period reduction.