在强烈地震作用下,大多数结构处于弹塑性阶段。材料具有明显的刚度退化作用。本文从输入,输出功率平衡出发,建立方程。在白噪声平稳随机过程情况下,可较容易的求得反应的方差。对多自由度体系,建议了输入功率对各振型的分配关系。从而可利用求单自由度体系反应方差的办法简捷的予以解决。数字例题说明结果是满意的。 Under strong earthquakes, most structures are in the elastoplastic stage. The material has a significant stiffness degradation effect. This article starts from the input, output power balance and establishes the equation. In the case of a white noise stationary random process, the variance of the response can be obtained easily. For multi-degree-of-freedom systems, the assignment of input power to each mode shape is suggested. Therefore, the solution to the variance of the single-degree-of-freedom system can be used to simply solve the problem. The numerical examples illustrate that the results are satisfactory.