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本文指出,许多随机载荷,诸如大气紊流、地面强风中紊流、路面不平度及海洋波浪产生的随机载荷,均可模型化为拟平稳高斯随机过程或场。在这种随机载荷作用下,线性结构的应力响应是一个拟平稳高斯随机场,可用一个含慢变参数的空间—时间互谱密度函数与一个这些慢变参数的联合概率密度函数来描述。在此情形下,结构的疲劳寿命与首次超越破坏的时间的概率密度函数与可靠性函数可由平稳高斯随机载荷下的相应结果加权平均得到,其权函数为应力响应谱密度函数中的慢变参数的联合概率密度函数。这样,大大地简化了在一大类统计特性缓慢变化的非平稳随机载荷作用下的结构的寿命与可靠性估计问题。
This paper points out that many stochastic loads, such as atmospheric turbulence, turbulence in surface strong winds, road irregularities and random loads generated by ocean waves, can be modeled as quasi-stationary Gaussian stochastic processes or fields. Under this kind of random load, the stress response of the linear structure is a quasi-stationary Gauss random field, which can be described by a space-time cross-spectral density function with slowly varying parameters and a joint probability density function of these slowly variable parameters. In this case, the probability density function and the reliability function of the fatigue life of the structure and the time of first surpassing the damage are obtained by the weighted average of the corresponding results under stationary Gaussian random loading. The weight function is the slow variation parameter in the stress response spectral density function. The joint probability density function. This greatly simplifies the life and reliability estimation of the structure under the influence of a non-stationary random load with a large variety of statistical characteristics that slowly changes.