An empirical model for amplitude prediction on VIV-galloping instability of rectangular cylinders

Niu, Huawei; Zhou, Shuai; Chen, Zhengqing; Hua, Xugang

doi:10.12989/was.2015.21.1.085

Cited by 11 publications

(8 citation statements)

References 24 publications

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“…According to the quasi-constant galloping force theory, the aerodynamic force can be obtained, as shown in equation ( 3). e research conclusion in [8] shows that the expansion term of the Taylor series for the quasi-constant galloping force can essentially meet the calculation requirements with consideration of the seventh order, and equation ( 4) is defined as the coefficient of the quasi-constant galloping force:…”

Section: Theoretical Modelmentioning

confidence: 99%

“…With regard to the fact that the onset wind speed of the "unsteady galloping" response can be roughly determined by the Strouhal law and the fact that the dimensionless response amplitude increases linearly with the dimensionless wind speed after vibration, Niu et al [8] identify two key parameters, that is, the onset wind speed point U 0 and the linear growth slope. A numerical study and regression analysis were then carried out, and an empirical formula for amplitude estimation was presented.…”

Section: Modified Empirical Formula For Amplitude Estimationmentioning

confidence: 99%

“…Niu et al [8] established a mathematical model of "unsteady galloping" by combining the vortex excitation model of the wake oscillator with two degrees of freedom (DOF) and a quasi-stationary vibration force model. e wind speed amplitude response curve was classified according to the coupling degree.…”

Section: Introductionmentioning

confidence: 99%

“…Niu et al [8] proposed an empirical formula applicable to the amplitude estimation of the "unsteady galloping" of rectangular section members. Studies have shown that the linear slope of the response curve under the coupled vibration state is a function of the ratio of the width of a member section to its height (B/D).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Investigation of the Scruton Number Effects of Wind‐Induced Unsteady Galloping Responses of Bridge Suspenders

Zhou

Zou

Hua

et al. 2021

Shock and Vibration

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When the critical wind speed of vortex-induced resonance is close to that of quasi-steady galloping, a type of coupled wind-induced vibration that is different from divergent galloping can easily occur in a rectangular bar. It is a type of “unsteady galloping” phenomenon wherein the response amplitude increases linearly with the increase in the wind speed, while a limit cycle oscillation is observed at each wind speed, whose mechanism is still in research. Mass and damping are the key parameters that affect the coupling degree and amplitude response estimation. For a set of rectangular section member models with a width-to-height ratio of 1.2, by adjusting the equivalent stiffness, equivalent mass, and damping ratio of the model system and performing comparative tests on the wind-induced vibration response of the same mass with different damping ratios, it is possible to achieve the same damping ratio with different masses and the same Scruton number with different masses and damping combinations under the same Reynolds number. The results show that the influence of the mass and damping parameters on the “unsteady galloping” amplitude response is independent, and the weight is the same in the coupling state. The Scruton number “locked interval” (12.4–30.6) can be found in the “unsteady galloping” amplitude response, and the linear slope of the dimensionless wind speed amplitude response curve does not change with the Scruton number in the “locked interval.” In addition, a “transition interval” (26.8–30.6) coexists with the “locked interval” wherein the coupling state of the wind-induced vibration is converted into the uncoupled state. The empirical formula for estimating the “unsteady galloping” response amplitude is modified and can be used to predict the amplitude within the design wind speed range of similar engineering members.

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Section: Theoretical Modelmentioning

confidence: 99%

Section: Modified Empirical Formula For Amplitude Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of the Scruton Number Effects of Wind‐Induced Unsteady Galloping Responses of Bridge Suspenders

Zhou

Zou

Hua

et al. 2021

Shock and Vibration

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“…The vortex-induced vibrations (VIV) may occur at relatively low wind velocities and would affect the safety and the comfortability of the structure. This is a serious problem for flexible structural components and for other offshore structures exposed to flowing fluids that have been investigated extensively [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Two-Dimensional and Three- Dimensional Responses for Vortex-Induced Vibrations of a Rectangular Prism

et al. 2020

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The accurate prediction of the amplitudes of vortex-induced vibrations (VIV) is important in wind-resistant design. Wind tunnel tests of scaled section models have been commonly used. However, the amplitude prediction processes were usually inaccurate because of insufficient evaluations of three-dimensional (3D) effects. This study presents experimental measurements of VIV responses in a prototype rectangular prism and its 1:1 two-dimensional section model in smooth flow. The results show that the section model vibrates with the same Reynolds number, equivalent mass, frequency, and damping ratio as those of the prototype prism without scale effects. The VIV amplitudes can be qualitatively and quantitatively measured and analyzed. The measured VIV lock-ins of these two models agree with each other. However, the prototype prism produces a 20% higher maximum amplitude than the section model. Several classical VIV mathematical models are used to validate the wind tunnel test results. This confirms that the 3D coupling effects of the modal shape and the imperfect correlations of excitation forces positively contribute to the maximum amplitude. Based on the section model outcomes, the amplified factor of 1.2 is found to be appropriate for the amplitude prediction of VIV for the present prism, and it can also provide a reference for other structures.

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Mathematical models for understanding phenomena: Vortex‐induced vibrations

Tamura

2020

Japan Architectural Review

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This is a rather biased review paper emphasizing the importance of "understanding" of phenomena. This paper's purpose is to inspire young researchers to taste the real charms of research by observing the process of development of mathematical models of vortex-induced vibration phenomena of cylinders for understanding their essential mechanism. It first discusses the limitations of human abilities and important aspects of research. Then, it emphasizes the close relation between understanding and mathematical models, and five conditions for a desirable mathematical model: simplicity; inclusion of all essential properties; possession of physical meanings; wide scope of application; and possibility of development. It refers to Birkhoff's wake-oscillator (1953), Funakawa's early-wake model (1969), Nakamura's 2DOF flutter model (1970), the Hartlen-Currie model (1970), the Iwan-Blevins model (1974), Tamura's non-linear wake-oscillator model with a variable length (1979), and the Tamura-Shimada model (1987) for combined effects of vortex resonance and galloping. Some recent developments of the Tamura-Shimada model are also introduced. Then, it discusses the necessity of accurate experimental capture of early-wake behavior and the aerodynamic properties of a target cylinder in a given flow condition for further development of Tamura's model and the Tamura-Shimada model. Finally, the necessity for efforts to understand phenomena are emphasized. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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An empirical model for amplitude prediction on VIV-galloping instability of rectangular cylinders

Cited by 11 publications

References 24 publications

Investigation of the Scruton Number Effects of Wind‐Induced Unsteady Galloping Responses of Bridge Suspenders

Investigation of the Scruton Number Effects of Wind‐Induced Unsteady Galloping Responses of Bridge Suspenders

Comparison of Two-Dimensional and Three- Dimensional Responses for Vortex-Induced Vibrations of a Rectangular Prism

Mathematical models for understanding phenomena: Vortex‐induced vibrations

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