Coherence characteristics of fluctuating lift forces for rectangular shape with various fairing decks

Ito, Yasuaki; Shirato, Hiroki; Matsumoto, M.

doi:10.1016/j.jweia.2014.10.003

Cited by 29 publications

(11 citation statements)

References 16 publications

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“…For long-span bridges, structure’s low natural frequency highlights the importance of force coherence in low-frequency region. Efforts have been made (Flay and Vickery, 1995; Ito et al, 2014; Jakobsen, 1997; Larose et al, 1998; Yan et al, 2016) for the empirical fitting of force coherence. Although some complex expressions like the Bessel functions (Kimura et al, 1997) can be found, most empirical fittings were in an exponential form.…”

Section: Major Resultsmentioning

confidence: 99%

“…However, the coherence of fluctuating forces does not coincide with the oncoming flow in the view of two facts: (1) aerodynamic force holds a larger integral scale and a stronger coherence. Studies showed the correlations of aerodynamic forces on airfoils (Etkin, 1972), bluff cylinders (Kimura et al, 1997; Sankaran and Jancauskas, 1993), and closed-box girders (Hjorth-Hansen et al, 1992; Ito et al, 2014; Jakobsen, 1997; Larose, 2003; Larose et al, 1998) are not the same with those of approaching flows. A bluff body smears out the incoherent components, resulting in the enhancement of aerodynamic coherence.…”

Section: Introductionmentioning

confidence: 99%

“…The deviation of force coherence from a simple e -exponential function leads to the empirical fitting of force coherence (Flay and Vickery, 1995; Ito et al, 2014; Kimura et al, 1997) and the discussion of turbulence effect (Larose et al, 1998; Yan et al, 2016). Due to the simplicity of exponential form, the 2-term expression by Flay and Vickery (1995) and the 3-term expression by Ito et al (2014) are convenient for application, but incapable for “low frequency curve.”Yan et al (2016) added an absolute term on Flay’s model. Although his model can fit the nonmonotonic coherence in a given region, it is indeed contradictory since the coherence turns to be negative infinity out of the fitted region.…”

Section: Introductionmentioning

confidence: 99%

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Span-wise coherence of fluctuating forces on twin bridge decks and the turbulence effect

Xia

2019

Advances in Structural Engineering

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Unlike the adequate researches on a single-box girder, the understanding of span-wise force correlation on twin decks is limited. A sectional model pressure testing of a widely slotted twin-box girder has been carried out in the background of a 5000-m-long bridge. Three grid configurations separated the effect of turbulence intensity and integral scale. Seven test sections were set on the model with totally 532 pressure taps. After the correction of pressure distortion, the correlation coefficients and integral scales of forces were compared on the leeward and the windward decks. Root coherence of lift was analyzed in detail at several separation distances. Pressure signals were used to explain why force coherence is stronger than flow and why “low frequency curve” phenomenon occurs. Considering the shortage of existing expressions, a simple but efficient form was proposed which can fit the coherence on the leeward, the windward, and the whole decks. The parameters in different flows can be reconstructed by linear functions which benefits new model’s application. In the final, the influences of turbulence intensity and integral scale on force coherence were illustrated.

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Section: Major Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Span-wise coherence of fluctuating forces on twin bridge decks and the turbulence effect

Xia

2019

Advances in Structural Engineering

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“…The measured fluctuating buffeting lift F L and moment M can be rendered dimensionless and expressed in terms of the coefficients of buffeting lift and moment ( C L b and C M b ) by equation (2). For long-span bridges under strong winds, the response components with reduced frequencies K = fB / U ≤ 1 . 0 are often dominant (Ito et al, 2014). Therefore, the cut-off frequency for the AAFs in this study was set as 15.6 Hz, corresponding to a cut-off reduced frequency of 1.0.…”

Section: Major Test Resultsmentioning

confidence: 99%

Identification of aerodynamic admittance functions of a flat closed-box deck in different grid-generated turbulent wind fields

Yan

Zhu

Flay

2017

Advances in Structural Engineering

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Wind tunnel tests of synchronous measurements of the buffeting lifts and moments on six separated strips of a motionless 1:45 scale sectional model of a flat closed-box bridge deck were carried out in three turbulent flow conditions. The longitudinal and vertical components of turbulent wind speed were also measured synchronously with the buffeting forces at the positions just over the windward edges of the six strips. Three typical methods, including the auto-spectral method based on the measured auto-spectrum of buffeting force (auto-spectrum method), the cross-spectral method based on the measured cross-spectra between buffeting force and fluctuating turbulence components (cross-spectrum method), and the colligated least square method based on a colligated residue of the above-mentioned auto- and cross-spectra (colligated least square method), were then used, respectively, to identify the aerodynamic admittance functions of the flat closed-box deck. The aerodynamic admittance function components of a buffeting force with respect to the longitudinal and vertical components of fluctuating wind speed were effectively separated using the colligated least square method while only a weighted average value, often called the equivalent aerodynamic admittance function, was obtained using the auto-spectrum method. Meanwhile, the reproduced auto-spectra of the buffeting forces had very high accuracies when the aerodynamic admittance functions identified with the colligated least square method were employed, but deviated significantly from the measured ones when the aerodynamic admittance functions identified with the cross-spectrum method were used. Furthermore, the influence of the span-wise position of the wind probe on the values of aerodynamic admittance function module was confirmed to be very small. Finally, the aerodynamic admittance function components with respect to the longitudinal and vertical fluctuating wind speeds were found to be significantly affected by both the intensities and integral scales of the oncoming turbulence wind.

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“…As an amplitude limiting vibration, vortex-induced vibration (VIV) could result in relatively large-amplitude vibration and discomfort for passengers on the bridges, thus special attention should be also paid to this factor in the design [ 6 , 7 , 8 ]. Basically, aerodynamic shape is one of important factors for the flutter and VIV performance of long-span suspension bridges, since an excellent aerodynamic shape could not only effectively improve the aerodynamic performance of long-span bridges, but also avoid the high costs in the construction of aerodynamic countermeasures [ 9 , 10 , 11 , 12 ]. Thus, it is necessary to further investigate the influence of aerodynamic shape on the flutter and VIV performance of long-span suspension bridges with closed-box girders.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Analysis of Geometrical Parameters on the Aerodynamic Performance of Closed-Box Girder Bridges

Yang

Zhou

et al. 2018

Sensors

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In this study, the influence of two critical geometrical parameters (i.e., angles of wind fairing, α; and lower inclined web, β) in the aerodynamic performance of closed-box girder bridges was systematically investigated through conducting a theoretical analysis and wind tunnel testing using laser displacement sensors. The results show that, for a particular inclined web angle β, a closed-box girder with a sharper wind fairing angle of α = 50° has better flutter and vortex-induced vibration (VIV) performance than that with α = 60°, while an inclined web angle of β = 14° produces the best VIV performance. In addition, the results from particle image velocimetry (PIV) tests indicate that a wind fairing angle of α = 50° produces a better flutter performance by inducing a single vortex structure and a balanced distribution of the strength of vorticity in both upper and lower parts of the wake region. Furthermore, two-dimensional three-degrees-of-freedom (2D-3DOF) analysis results demonstrate that the absolute values of Part A (with a reference of flutter derivative A2*) and Part D (with a reference of A1*H3*) generally decrease with the increase of β, while the change of the participation level of heaving degrees of freedom (DOF) in torsion-dominated coupled flutter initially increases, reaches its peak, and then decreases with the increase of β.

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Coherence characteristics of fluctuating lift forces for rectangular shape with various fairing decks

Cited by 29 publications

References 16 publications

Span-wise coherence of fluctuating forces on twin bridge decks and the turbulence effect

Span-wise coherence of fluctuating forces on twin bridge decks and the turbulence effect

Identification of aerodynamic admittance functions of a flat closed-box deck in different grid-generated turbulent wind fields

Sensitivity Analysis of Geometrical Parameters on the Aerodynamic Performance of Closed-Box Girder Bridges

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