基于EMD的长周期地震动分量提取方法

谭潜 李英民 杨永斌

摘 要：在实际地震记录形成过程中存在高、低频成分地震波的叠加，地震动高、低频成分的组成是地震动反应谱特征的重要反映。采用数字滤波技术，以加速度反应谱平均周期2 s为截止周期，结合经验模态分解，提取2 s以上的本征模态函数及残值重构并基线校正后作为长周期分量，其余本征模态函数重组为短周期分量;通过原地震动与分量的相关性、反应谱的离散性对提取方法的有效性进行验证，并与既有方法进行对比。结果表明：该长周期地震动分量提取方法能较好地提取出在长周期和短周期部分与原地震动具有较好的相关性、地震反应谱离散性较小的长、短周期分量，且较好地反映原地震动的谱特征，在长周期地震动分量提取中具有更好的适应性。

关键词：长周期地震动;经验模态分解;本征模态函数;反应谱;频谱参数;长周期分量

中图分类号：P315.5;P315.9 文献标志码：A 文章编号：2096-6717（2021）03-0119-09

Abstract： In the actual seismic record formation process， there is a superposition of high and low frequency components of seismic waves. The composition of high and low frequency components of ground motion is an important reflection of the characteristics of the response spectrum of ground motion. This study is based on the digital filtering technology， taking the average period of acceleration response spectrum （Tavg） 2 s as the cut-off period and combining with empirical mode decomposition（EMD）， and it extracted the intrinsic mode function（IMF） and residual component which the cut-off period above 2 seconds as long-period components of long period ground motions（LPGM） after refactoring and baseline correction. The remaining IMFs were reorganized into short-period components; The validity of the extraction method is verified by correlation between seismic records and their components and the discreteness of the original ground motion and the response spectrum. It also compare this method with existing methods. The results show that the extraction method for LPGM components in this paper can better extract the long and short period components of the seismic response spectrum that are less discrete and have a good correlation with the original ground motions in the long and short periods respectively. It better reflects the spectral characteristics of original ground motions and has better adaptability in the LPGM component separation.

Keywords： long-period ground motions; empirical mode decomposition（EMD）; intrinsic mode function（IMF）; response spectrum; spectral parameter; long period component

在实际地震记录形成过程中，存在各种成分地震波的叠加（图1）[1]，故地震记录的主要特性由其主要成分特性来表达更具代表性。对地震动原始记录的分析处理是以往研究地震动的主要方向，其忽视了地震动分量分析，而地震记录中存在长周期分量的事实不能否认[2]。在长周期地震动界定中，徐龙军等[3]以规准反应谱的离散性分析为基础，指出地震动的反应谱特征与地震记录的长周期分量是不可忽视的两个方面。对地震记录各类分量的提取和分析是确定地震动类型的可靠方法。……