基于高斯函数的完全非平稳地震动多峰模型及其应用

Gaussian function based evolutionary power spectral density model for fully non-stationary seismic waves and application

地震动非平稳特征对非线性结构地震反应的影响不可忽视,并且地震动非平稳特征的准确描述对工程用人工地震波的生成也具有重要意义。在非平稳过程谱表现法的基础上,采用多个高斯函数叠加的包络函数对各频率分量进行调制,建立了一种更加符合地震动非平稳特征的多峰演变功率谱密度模型;基于广义谐和小波,利用Spanos-Tratskas方法计算实际地震动的演变功率谱密度,在预识别峰值相关参数的基础上采用遗传算法进行模型参数识别;选取KiK-net地震波数据库中近2 500条实际地表地震动记录,验证本模型的适用性,通过算例进行了实际应用。结果表明,所提出的多峰演变功率谱密度模型可以实现强度调制在各频率点的自适应性,特别是在中高频段能较好模拟地震动的多峰特征。通过基于高斯函数的多峰演变功率谱密度模型及其参数识别,将地震动的非平稳特征提取到模型参数中,使得地震动非平稳特性的研究可以通过对其参数的分析实现。所提出的模型可以为地震动非平稳特性的研究提供参考。

The non-stationary feature of seismic ground motions has an important effect on the nonlinear dynamic response of structures, which makes it of great significance to accurately describe the non-stationary feature of seismic ground motions when generating artificial seismic waves. Based on the formula of spectral representation, the non-stationary feature of seismic ground motions was described by evolutionary power spectral density, which modulated the synthesized seismic waves by Gaussian function at each frequency section. General harmonic wavelet based Spanos-Tratskas method was adopted to calculate the evolutionary power spectral density of seismic ground motions. Combining peak pre-recognition technology and genetic algorithm, the fitting of evolutionary power spectral density(EPSD) model and target actual EPSD was achieved. A total of nearly 2 500 seismic ground motion records are selected from KiK-net earthquake databank to verify the applicability of proposed model, and several examples were provided. The results show that the proposed model can well fit the temporal envelope of EPSD at each frequency, especially at medium and high frequency components. The modeling of EPSD can extract the information of non-stationarity into identified model parameters, then the underlying pattern can be revealed by statistical analysis of model parameters. The proposed model provides a feasible way to study the non-stationary features of seismic ground motions.