基于工程特性的主余震型地震动降维模拟

Dimension reduction simulation of main-aftershock-type ground motions based on engineering characteristics

余震是由主震孕育而来,两者之间存在着一定的关联性,如何构造主余震型地震动模型,是工程结构抗震分析的基础。着眼于地震动的工程特性,根据主余震之间的峰值加速度、强震持时、场地卓越频率等要素,分别建立主震和余震自身的演变功率谱模型,基于非平稳随机过程的谱表示,通过引入随机函数降维模拟方法,实现仅用三个基本随机变量即可精确模拟主余震型地震动过程。研究表明,采用该降维模拟方法的效率和精度均满足工程需求,且与实测主余震型地震动记录的反应谱和幅值谱拟合一致,验证该模型与方法的优越性,为工程结构在主余震型随机地震作用下的抗震分析提供有效途径。

Aftershocks are produced from mainshock,indicating a certain correlation between them.Thus,establishing a main-aftershock ground motion model will serve as the basis of seismic analysis for engineering structures.Based on the characteristics of a main-aftershock-type ground motion,such as peak acceleration,strong earthquake duration,and predominant frequency of the site,evolution power spectrum models of aftershocks and mainshocks were established in this paper.Then,based on the spectral representation of a nonstationary random process,the main-aftershock-type ground motion can be accurately simulated with three basic random variables using the dimension reduction simulation of the stochastic function.Numerical examples show that the efficiency and accuracy of the dimension reduction simulation used in this paper can meet engineering requirements.Simulated results are consistent with the fitting between response and amplitude spectra of the measured ground motion records.This verifies the superiority of the model and the method developed in this paper,thereby providing an effective way for seismic analysis of engineering structures subjected to main-aftershock stochastic earthquakes.