Predicted aerodynamic damping of slender single beam structures in across-wind vibrations
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RESEARCH ARTICLE
Predicted aerodynamic damping of slender single beam structures in across‑wind vibrations Cung Huy Nguyen1 · Dinh Tung Nguyen2 Received: 15 January 2020 / Revised: 25 May 2020 / Accepted: 17 July 2020 © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The paper presents a generalization of the conventional analytical approach where the quasi-steady theory is utilised to evaluate the across-wind aerodynamic damping of slender single beam structures. This generalized theory considers the variation of structural and aerodynamic parameters along the structural height, together with the nature of the vertical wind profile and mode shapes. Closed-form solutions for typical uniform and tapered tall buildings are given. A numerical application on a prototype tall building shows that the conventional method may be oversimplified, which results in incorrect predictions of the aerodynamic damping. Keywords Aerodynamic damping · Across-wind · Slender structure · Galloping · Tall building
1 Introduction Slender single beam structures such as antennas, poles, towers, tall buildings are vulnerable to winds and are susceptible to large dynamic vibrations and galloping instability. The aerodynamic damping of these structures is generated due to wind-structure interaction. The structures are benefited from positive aerodynamic damping. In contrast, the negative aerodynamic damping poses a detrimental effect since it reduces the total damping of the structure. When the total damping of a structure reaches a negative value, galloping instability will occur in across-wind vibrations [1] or nonacross-wind vibrations [2]. Commonly, the along-wind aerodynamic damping is neglected because it is positive and small [3]. On the other hand, the across-wind aerodynamic damping is of interest since it may be negative. Recent and future tall structures tend to be more slender and have more complex shapes that may lead to a negative slope of the lift coefficients, potentially resulting in negative across-wind aerodynamic damping [4–6]. Across-wind aerodynamic damping can * Cung Huy Nguyen [email protected] 1
Department of Civil Engineering, Industrial University of Ho Chi Minh City, Ho Chi Minh City 700000, Vietnam
Department of Civil Engineering, University of Nottingham, Nottingham NG7 2RD, UK
2
be estimated through full-scale measurements [7, 8], wind tunnel tests [5, 9–12], or computational fluid dynamics (CFD) simulations [13]. Analytical method to predict the aerodynamic damping is useful in early design stages. For this purpose, quasi-steady theory has been widely applied to estimate the across-wind aerodynamic damping as reviewed in Ref. [1]. The very early model of across-wind aerodynamic damping and transverse galloping using the quasi-steady theory is referred to the Den Hartog’s theory [1]. Den Hartog’s criterion has been widely used in engineering application thanks to its simplicity. Following the study of Den Hartog
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