密集模态结构模态跃迁分析的简化摄动法

大跨空间结构的模态具有密集、低频的特性。结构在风作用下会产生非常复杂的动力学现象,模态跃迁就是其中的一种。以往对该类结构模态跃迁特性的研究几乎为一片空白。矩阵摄动分析法是研究变参数结构模态特性的重要方法,在已有矩阵摄动法基础上,该文提出分析密集低频结构模态跃迁现象的简化摄动法。阐述模态跃迁的机理,并加以证明。算例结果表明:简化摄动法用于密集低频结构模态跃迁的分析是有效、可行的,且简化了移位密集特征值摄动法的计算过程。

SIMPLIFIED PERTURBATION METHOD FOR ANALYZING THE MODE JUMPING OF CLOSE MODE STRUCTURE

The frequency of a long span spatial structure is close and low.When a wind load is applied on the structure,complex dynamic phenomena occur such as mode jumping.But few studies have paid any attention on the mode jumping of this type of the structure.The matrix perturbation method is more suitable for analyzing modal characteristics of the variable parameter system.This paper improves the former perturbation method to research the mode jumping of a close mode structure.The mechanism of the occurrence of the mode jumping is elaborated and certified.The results of examples show that the simplified method is effective and reliable;meanwhile,it can reduce the calculation time remarkably with respect to the former methods.