地震动功率谱实用模型的低频段合理性分析

摘要

由规范反应谱合成的地震动功率谱实用模型具有较高的工程应用价值.提出从功率谱零频含量特征和地面最大位移2个方面判断地震动功率谱实用模型低频段的合理性.以多国规范反应谱为目标谱合成地震动功率谱,对比分析各功率谱低频段的合理性.分析结果表明,由加速度反应谱合成的功率谱的合理性取决于反应谱的合理性,而合理的加速度反应谱在长周期（低频）段应随周期（T）的增长以T-2的速度下降.据此修正GB50011—2010反应谱,引入T-2下降段,并将起始下降周期初步定为2 s.%The practical power spectrum density function（PSDF） of earthquake ground motion produced based on the response spectrum（RS） is very useful in engineering applications.The rationality analysis of the low-frequency stage of the practical PSDF based on several response spectrum of different codes is carried out on the base of two aspects,both rationality of the characteristics of PSDF value at zero frequency and the peak displacement of ground motion.Results show that the rationality of PSDF depends on that of RS.RS value at the long-period（low-frequency） stage must attenuate at the speed of T-2 with increasing period T.Then descending stage of T-2 is adopted to improve the RS curve of Chinese code GB50011—2010.An estimated value of 2 s is proposed as the starting period of the T-2 descending stage.