中文摘要：

地震动强度非平稳特性对结构非线性响应有显著影响，准确描述强度非平稳特性对生成人工地震波有重要意义。该文提出了一种描述三维地震动强度非平稳特性的模型，分别给出了其确定性参数取值和随机参数取值。首先以大量KiK-net强震记录为样本，提取其强度非平稳特性；然后选取地震动强度非平稳模型，并使用遗传算法识别出了模型的参数；最后通过统计回归分析给出了各震级、震中距不同场地类别的三维模型参数取值。结果表明，所得强度非平稳模型能够反映地震动强度非平稳特性的规律，可将其用于结构抗震分析和人工地震动模拟中。

英文摘要：

Non-stationary characteristics of ground motion intensity have remarkable effect on the nonlinear response of structures, and accurate description of non-stationary characteristics of ground motion intensity is of significance to generating artificial earthquakes. In this work, a model for non-stationary characteristics of three-dimensional ground motion intensity was proposed, and the values were given for the deterministic parameters and the stochastic parameters, respectively. Firstly, a series of actual non-stationary characteristics were extracted from a large number of KiK-net earthquake records. Then, a non-stationary model of ground motion intensity was chosen and its parameters were identified by the genetic algorithm. At last, the parameter values were determined for the three-dimensional model under different earthquake magnitude, epicentral distances and site conditions. The results show that the model proposed in this study can reflect the law of non-stationary characteristics of ground motion intensity, and it can be used in structural anti- seismic analysis and artificial earthquake simulation.