基于EMD和VARMA模型的地震动仿真

Simulation of earthquake ground motions by using EMD and VARMA model

通过EMD方法将地震动分解成若干固有模态函数,提出了用固有模态函数的时变VARMA建模实现地震动仿真的思路。算例分析表明,该方法充分利用了固有模态函数的特性,解决了直接基于ARMA或VARMA模型建模的仿真方法所面临的模型判阶的难题,并可同时考虑地震动的强度和频率非平稳特性,使仿真地震动与实际地震动在能量时频分布特性上具有较好的一致性且样本统计性较好,弹性及弹塑性反应谱拟合精度较高。

By using the empirical mode decomposition （EMD） method to decompose the earthquake ground motion to a finite set of intrinsic mode functions （ IMFs）, a simulation method based on the time varying VARMA modeling of IMFs is proposed. The numerical results indicate that having advantage of the characteristics of IMFs the method resolves the problem of model order selection, with which the ARMA or VARMA model based methods are confronted and can simultaneously take into account the nonstationarity in amplitude and frequency contents of earthquake ground motions. It is also confirmed that the method has an agreement in energy-time-frequency distribution between the synthesized and the actual ground motions and gives a good performance in sample characteristics and compatibility of elastic and elasto-plastic response spectra.