Galloping of forward and backward inclined slender square cylinders

Hu, Gang; Tse, K.T.; Kwok, K.C.S.

doi:10.1016/j.jweia.2015.04.010

Cited by 50 publications

(15 citation statements)

References 36 publications

(34 reference statements)

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“…The present study investigates the flow field around a rigid inclined finite square cylinder in order to understand its aerodynamic behavior and flow-induced vibration, which have been demonstrated to be different from a vertical finite square cylinder (Hu et al, 2015;Tse et al, 2014). A series of LES and wind-tunnel experiments were conducted.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation of flow around an inclined finite square cylinder

Tse

Kwok

et al. 2015

Journal of Wind Engineering and Industrial Aerodynamics

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Section: Introductionmentioning

confidence: 99%

Large eddy simulation of flow around an inclined finite square cylinder

Tse

Kwok

et al. 2015

Journal of Wind Engineering and Industrial Aerodynamics

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“…Details about galloping prediction of the test model can be found in a previous study [3]. Figure 11 shows that the onset galloping wind speed evaluated by the quasi-steady theory is 0.71 r U  that corresponds the reduced wind speed of 28.3…”

Section: Comparison With Quasi-steady Theorymentioning

confidence: 92%

“…Galloping is characterized by a divergent-type of self-controlled aerodynamic instability, which often occurs on slender structures, such as transmission lines [1,2] , bridge pythons [3] , bridge deck sections [4] . Due to its destructiveness, galloping of structures has attracted much attention by engineers and researchers.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, as illustrated in a previous study [11], the quasi-steady theory cannot predict the oscillations of structures at the second galloping region, which means the quasi-steady theory is not applicable for the region after galloping occurs. In addition, Hu et al [3,12] pointed out that the quasisteady theory is not applicable for backward and forward inclined prisms, which may be attribute to the effect of the axial flow and vortex shedding of the prisms. This study aims to (1) propose a HPAT technique, (2) measure the unsteady galloping force, and (3) improve the galloping prediction of the slender prism.…”

Section: Introductionmentioning

confidence: 99%

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Unsteady Galloping Force and Response Prediction of a Slender Prism Using a Novel Wind Tunnel Test Technique

Chen¹,

Tse²,

Kwok³

et al. 2017

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This paper examines a new measure of the unsteady galloping force of a slender prism using a hybrid pressure-aeroelastic test (HPAT) technique. The HPAT was performed to simultaneously observe the unsteady crosswind force and response of a test model. The observed crosswind force contains amplitude-dependent non-windinduced aerodynamic force that was caused by the interaction between the oscillating test model and the surrounding air. The unsteady galloping force of the test model was therefore evaluated by removing the non-wind-induced aerodynamic force identified by using a forced vibration technique from the observed unsteady crosswind force. The amplitude-dependent mechanical nonlinearities (damping and stiffness) of the HPAT system were identified by using a wavelet method from a free decay response of the test model. By substituting the obtained unsteady galloping force and the mechanical nonlinearities into the governing equation of motion of the test model, the galloping responses of the test model were predicted. The results show that the galloping responses of the test model predicted by the identified unsteady galloping force are identical to the experimentally measured response, and ________________________ 21the unsteady galloping force can give a better galloping prediction than a classical quasi-steady theory, indicating that both the HPAT technique and the identified unsteady galloping force were accurate and reliable. This study provides a way to address the problem that the classical quasi-steady theory is, in some cases, not applicable in galloping predictions of three-dimensional prisms.

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“…The quasi-steady theory also allows the calculation of the post-critical amplitudes of vibration [8][9][10][11][12] and it has also been applied to the case of a yawed cylinder [13]. Nevertheless, the limits of this theory for practical applications have been highlighted in many works [14][15][16][17]. Interestingly, the galloping instability of a forward and a backward inclined square prism has recently been experimentally and numerically investigated in [17][18][19], which emphasize the differences as compared to the case of the same cylinder perpendicular to the incoming flow and provide a physical explanation for the results.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Aeroelastic stability of two long-span arch structures: A collaborative experience in two wind tunnel facilities

Mannini

Belloli

Marra

et al. 2016

Engineering Structures

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a b s t r a c tIn this paper, a rare example of comparison between sectional and full-aeroelastic model tests is presented. Interestingly, the experiments were conducted in two very different wind tunnel facilities by different research teams. The study concerns two long-span steel arch structures recently built in Milan, Italy, for Expo 2015 World Fair. The structures have only aesthetic purposes and are therefore very flexible and light, which makes them sensitive to wind-induced excitation and prone to aeroelastic instabilities. In particular, in smooth flow an interesting phenomenon of interference between vortex-induced vibration and galloping was observed up to high values of the Scruton number. This aeroelastic instability is very dangerous as large-amplitude vibrations can occur in wind speed ranges where they are not expected, at least for what classical theories for vortex-induced vibration and quasi-steady galloping are concerned. Moreover, the provisions of Eurocode 1 resulted clearly unsuitable and nonconservative to address such a phenomenon. Despite the differences in the facilities and in the models, a good agreement was found between the results obtained in the two laboratories. The major discrepancies were observed in the transitional behavior for intermediate values of the Scruton number, the sectional model showing a more unstable behavior. The tests on the full-aeroelastic model also allowed considering the effect of the angle of wind exposure of the structures, both the in-plane and the out-ofplane vibrations of the arches and the dynamic response to turbulent wind. In particular, a set of tests in smooth flow was performed accounting for the presence of the other arch and of the surrounding buildings. A particular dynamic excitation of the in-plane flexural modes of the structures was observed in well defined ranges of flow speeds when one arch is in the wake of the other. Finally, both experimental campaigns highlighted the need for the installation of tuned mass dampers on the real structures to guarantee their safety. The effectiveness of these devices against the observed galloping-type instability was also verified through wind tunnel tests on the full-aeroelastic model.

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Galloping of forward and backward inclined slender square cylinders

Cited by 50 publications

References 36 publications

Large eddy simulation of flow around an inclined finite square cylinder

Large eddy simulation of flow around an inclined finite square cylinder

Unsteady Galloping Force and Response Prediction of a Slender Prism Using a Novel Wind Tunnel Test Technique

Aeroelastic stability of two long-span arch structures: A collaborative experience in two wind tunnel facilities

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