汶川地震地震动持时特性分析

Analysis of Ground Motion Duration Characteristics of Wenchuan Earthquake

摘要: 基于目前常用的几种地震动持时定义，利用汶川地震中由中国数字强震动台网记录的地面运动加速度时程，分析并比较了不同定义下地震动持时的统计结果，结果表明，此次地震引起的地震动具有较长持时特点，且不同持时定义给出的统计结果存在较大差异，同一台站，绝对强震持时最长，而70%能量持时最短。此外，利用破裂前后方典型强震动台站加速度记录，重点分析了地震动持时的方向性分布特征，结果显示，破裂前方的地震动加速度时程持时随震中距无明显变化趋势，而破裂后方的持时随震中距增加而不断增加，且破裂前方的持时明显小于破裂后方的持时。本文结果可为地震动持续时间对结构地震反应影响的研究提供参考。

Abstract: Based on several commonly used definitions of ground motion duration, the statistical results of ground motion duration under different definitions are analyzed and compared by using strong motion acceleration data recorded by China Earthquake Network Center in Wenchuan Earthquake. The results show that the ground motion induced by this earthquake has long duration characteristics, and the statistical results given by different definitions of ground motion duration are quite different. On the other hand, at the same station, absolute strong earthquake duration is the longest and 70% energy duration is the shortest. In addition, using the acceleration records of typical strong motion stations forward and backward rupture, the directional characteristics of ground motion duration are analyzed. The results show that the time duration of ground motion acceleration forward rupture has no obvious trend with the epicenter distance, while the time duration backward rupture increases with the epicenter distance, and the time duration forward rupture is obviously shorter than that behind rupture. The results of this paper can be useful for the study of the influence of the ground motion duration on the seismic response of structures.