基于时变功率谱的非平稳加速度时程合成研究

Method of Nonstationary Ground Motion Synthesizing Based on Evolutionary Power Spectra

加速度时程频率非平稳性对结构地震反应影响显著,工程中常用的拟合目标反应谱的时程合成法不能反映频率的非平稳性。为了得到强度和频率非平稳时程,采用多重滤波技术计算记录的时变功率谱,分析时变功率谱模型参数随震级、震中距及频率的变化规律并建立相应的衰减模型;利用衰减模型进行强度和频率非平稳加速度时程合成分析。通过对合成时程和强震记录时程的峰值加速度、强震持时及反应谱的对比分析,论证模型及合成方法的合理性和有效性。

The nonstationarity of acceleration time-frequency has significant impacts on seismic response of structure. The superposing technique of trigonometric function matching with the target spectrum does not reflect the nonstationarity in frequency. For synthesizing the nonstationary acceleration time histories in amplitude and frequency, the evolutionary power spectra is calculated by multi-filter technique, and the laws of evolutionary power spectra model parameters varied with magnitude, hypoeentral distance and frequency of earthquake are analyzed and the attenuation equations are developed. By using the attenuation equations, the nonstationary acceleration time histories in amplitude and frequency are synthesized respectively. After comparing total energy, peak ground acceleration, duration and response spectra of synthetic acceleration time histories with recorded strong motions, the rationalities of attenuation equations and synthesized method are proved.