利用正交Hilbert谱模拟非平稳随机地震动

基于样本记录正交HHT变换的Hilbert谱提出了非平稳随机地震动过程的模拟方法。 利用正交EMD法对IMF分量进行处理，克服了传统EMD分解存在能量泄漏的缺点，使正交HHT法可以精确分析非平稳信号的时频特性。在此基础上，把样本的Hilbert谱均值作为地震动随机过程的目标Hilbert谱，引入随机相位角来进行非平稳随机地震动过程的仿真，并且给出了随机过程的统计特性函数。通过对2个地震动记录的模拟，验证了模拟的地震动样本，能完全反映原记录强度和频率的非平稳特性，在时频分布上和原记录非常接近，具有相同的统计特征，并且模拟样本之间也具有良好的离散性。

Simulation of nonstationary stochastic earthquake ground motion based on orthogonal Hilbert spectrum

A new method is proposed for the simulation of nonstationary stochastic earthquake ground motion based on orthogonal Hilbert-Huang transform (OHHT) spectra of its sample observations. Orthogonal EMD method is introduced to treat with IMF. OHHT avoids leakage of energy compared with conventional HHT, and it can be used for analysis of nonstationary signal. The average of the Hilbert spectra over the samples is defined as the Hilbert spectrum of the earthquake motion process and used as the target in the simulation of the process. Random Phase is also introduced to simulate nonstationary earthquake. The statistic characteristics function of stochastic process is given in the paper. Simulations of two earthquake ground motion are carried out. The results show that the samples can accurately reflect amplitude and frequency nonstationary of records. Samples and record of same earthquake ground motion process have same statistic characteristics.