中文摘要：

首先推导了离散S变换的基本算法，定义了反映地震波时频特性的时变幅值谱和时变能量谱；以Kobe地震波为例，基于S变换分析了该地震波的时频特性，并对采用不同窗口函数的分析结果进行了对比，分析发现当适当地调整窗口参数，复窗口的广义S变换对非平稳地震波有较好的时频分辨率；利用S变换的时频滤波性质，对实际地震波进行了任意时间和频率段的人工调整；以与抗震规范相容的功率谱为目标谱，提出了利用S变换合成非平稳地震波的新方法，通过实例分析发现，人工合成的地震波功率谱与目标谱符合很好，而且继承了母波的非平稳特性；还研究了地震波的时频特性对单自由度体系弹性反应谱的影响。

英文摘要：

The formulas of discrete S-transform are derived, and the time-varying amplitude spectrum and time varying energy spectrum based on S-transform are given. The time-varying energy spectrum of Kobe wave is estimated by using S-transform with different window function, numerical results show that the improved S-transform is the effective method when choosing the time window parameter properly. Earthquake records can be adjusted with time-frequency filtering based on S-transform, and a new procedure is presented to generate an accelerograms whose power spectrum is compatible with a target spectrum by using actual earthquake records as parents. It is showed that the power spectrums of reconstructed accelerograms have good matching with the target spectrum and preserve the non-stationary features of the parents accelerograms. Finally, the effects of the non-stationary frequency characteristic of ground motions on the response spectrum are investigated.