芦山7．0级地震强震动记录及其震害相关性

Strong motion records and their engineering damage implications for Lushan Earthquake on April 20,2013

2013年4月20日芦山地震中的强震动记录是我国自2008年汶川地震后再一次比较全面地获得的高质量的数字强震动记录。国家数字强震动台网共获得3分量自由场记录114组,成都地震烈度速报台网获得63组。文章对强震动记录进行了常规处理,统计了强震动记录随断层距的数量分布情况,绘制了空间地震动加速度等值线图。结合芦山地震震源机制解和破裂过程研究成果,选取典型记录,分析加速度、速度时程的波形、振幅等特征,识别了此次地震滑冲现象,估算了竖向最大永久位移。通过利用观测数据与国外的地震动预测公式对比,分析了不同周期反应谱地震动幅值及加速度反应谱衰减规律,阐明了此次地震的地震动在近场高频成分较卓越的特点。震后现场考察了3个典型强震动台站附近建筑物震害,分析了地震动与工程震害的相关性,地震烈度的评定反映了地震破坏的程度。

The Lushan Earthquake occurred on April 20, 2013 is another destructive event after Wenchuan Earth- quake in 2008. During the main shock, 114 strong motion records were accumulated by the National Strong Motion Observation Network System （NSMONS） of China and 63 records by the Local Earthquake Intensity Reporting Net- work of Chengdu City. The preliminary characteristics of these records were given including the station spatial loca- tions, PGA contours and records numbers within different rupture distance. The analyzed results show the character- istics of predominant high-frequency components and short duration for this event. The fling step was identified on the basis of the velocity time histories of the hanging wall stations and then the maximum permanent displacement of this earthquake was evaluated. The observed PGAs and spectral accelerations were also compared with the ground motion prediction equation commonly used in Italy, which shows the observed PGAs and high -frequency spectral accelerations have a good agreement with the empirical predicted ones but the moderate and long -period compo- nents are remarkably lower. The post-field investigation also found that the macro intensities around 3 selected typi- cal stations match well with their surround damage.