【摘要】 地震地面运动过程具有强烈的随机性,应用随机理论对实际工程结构进行地震可靠性分析和抗震设计与加固时都需要建立合理的随机地震地面运动模型。本文选择3种典型的随机地震动模型,即理想白噪声模型、金井清模型和改进的金井清模型,分析了它们的物理概念、频域特征以及适用范围。引入状态向量,建立状态方程,通过复振型叠加法分析了地震地面运动过程的时域统计特性,推导出3种随机地震动模型的相关函数的解析表达式。这些结果可为结构随机地震反应时域分析和抗震可靠性评估提供基础。更多还原

【Abstract】 There are vast uncertainties and randomness in predicting intensities of resulting ground motions, so the earthquake-induced ground motions are usually considered as stochastic processes, and probabilistic methods should be used in order to consistently account for the underlying uncertainties and randomness involved in the load- structure system and make quantitative assessment of structural vulnerability and safety subject to earthquake excitation. In this paper, three models of stationary Gaussian random process with the power spectra of white noise, Kanai-Tajimi and modified Kanai-Tajimi, respectively are researched for representing the actual earthquake ground accelerations. It is proved that the Kanai-Tajimi spectrum is essentially the filtered Gaussian white noise process, and the modified Kanai-Tajimi spectrum is the result that a Gaussian white noise process with mean value of zero is filtered twice. Based on the physical meanings of Kanai-Tajimi spectrum and modified Kanai-Tajimi spectrum, the state equations are established and the covariance functions of the stochastic models are deduced by correlation method in time domain. These results provide a basis for random response analysis and reliability assessment of the earthquake-resistant.更多还原