Initial undamped resonant frequency of slender structures considering nonlinear geometric effects: the case of a 60.8 m-high mobile phone mast

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• 作者：Alexandre de M. Wahrhaftig…
• 关键词：Actual structure ; Natural frequency ; Rayleigh method ; Structural dynamics ; Finite element method
• 刊名：Journal of the Brazilian Society of Mechanical Sciences and Engineering
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：39
• 期：3
• 页码：725-735
• 全文大小：
• 刊物主题：Mechanical Engineering;
• 出版者：Springer Berlin Heidelberg
• ISSN：1806-3691
• 卷排序：39

文摘

In this study, an analytical approach based on the Rayleigh method is adopted to calculate the first resonant frequency of a 60.80 m-high mobile phone mast system, by considering the geometric stiffness, functions of the concentrated forces, and self-weight of the structure. Such a technique is applicable to continuous systems with infinite degrees of freedom. However, it is important to bear in mind that actual structures are more complex than simple systems, such as beams and columns, because the properties of actual structures vary with their length. For comparison, a finite element method (FEM)-based computer simulation is performed. First, the axial forces on each segment of the structure are compared. Then, under geometric nonlinearity, the vibration frequency of the fundamental mode is calculated analytically. Finally, the structural stiffness is evaluated. The results of the analytical approach are found to differ slightly from those of the FEM-based model.