On the effects of the gap on the unsteady pressure characteristics of two-box bridge girders

Trein, Cristiano Augusto; Shirato, Hiroki; Matsumoto, M.

doi:10.1016/j.engstruct.2014.10.036

Cited by 18 publications

(6 citation statements)

References 28 publications

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“…The most noticeable differences can be found for the * flutter derivatives, since the larger the gap distance, the higher the negative value of this flutter derivative. This is in agreement with the findings in [12], and explains the improved aeroelastic performance of twin-box decks since the larger the gap is, the higher the aerodynamic damping related with the velocity of rotation for the aeroelastic moment. In addition, differences can be found for the flutter derivatives * and * , where the longer the gap distance, the lower the absolute value of the flutter derivatives for the same reduced velocity.…”

Section: Flutter Derivativessupporting

confidence: 92%

“…The literature on the subject focused on the flutter response, which was much improved compared to mono-box designs, the vortex-induced excitation risk, that is the main drawback of this deck arrangement, as well as Reynolds number effects [2]- [12]. More recently, the effect of the boxes' geometry has also been studied [13], [14], as well as the effect of aerodynamic appendages [15].…”

Section: Introductionmentioning

confidence: 99%

“…In fact, the gap to depth ratio (G/D, being G the gap distance and D the depth of the girder) of the Stonecutters Bridge is about 4:1, while this ratio for the Xihoumen Bridge is 1.7:1. Furthermore, short gap lengths are generally favoured since construction costs increase with the gap length [12].…”

Section: Introductionmentioning

confidence: 99%

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Wind Tunnel Study on the Effect of the Gap Width in the Aerodynamic and Aeroelastic Responses of Twin-Box Decks

Nieto

Montoya

Fontán

et al. 2018

Advances in Fluid Mechanics XII

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Twin-box decks have recently been introduced in long-span bridges because this type of slotted crosssection provides flutter critical wind speeds higher than mono-box streamlined decks for flexible structures. The two parallel girders are linked together by means of transverse beams with a central gap between them. Experimental and CFD studies have shown that the length of this central gap plays a key role in the aerodynamic and aeroelastic responses of the deck. In this work, the geometry of the Stonecutters Bridge in Hong Kong (China) has been chosen as an application case to conduct a series of parametric studies based on wind tunnel tests. The tests have been conducted under smooth flow, for a 1:80 geometric scale sectional model able to modify its slot length. For an ample range of gap lengths, the force coefficients and the flutter derivatives have been obtained. It has been found that the slopes of the lift and moment coefficients suffer important changes with the gap length. In the same manner, it has also been found that the gap distance modifies the values of flutter derivatives. Finally, for a longspan bridge example, the critical flutter speeds for different gaps are obtained, aiming to identify the gap length that provides a safer threshold for the flutter phenomenon. The results reported herein permit the assessment of the impact caused by the gap length in the aerodynamic and aeroelastic responses of twin-box decks.

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Section: Flutter Derivativessupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Wind Tunnel Study on the Effect of the Gap Width in the Aerodynamic and Aeroelastic Responses of Twin-Box Decks

Nieto

Montoya

Fontán

et al. 2018

Advances in Fluid Mechanics XII

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“…Twin-box girders with a center gap between two girders has been proven to be one of the effective aerodynamic countermeasures for improving the aerodynamic performance of long-span cable-supported bridges, and so its implementation becomes increasingly popular for long-span, or even super long-span bridges [1,2,3], e.g., Xihoumen Bridge with the main span of 1650 m (China) and Gwangyang Bridge with the main span of 1545 m (Korea). Nevertheless, twin-box girders with various Slot Width Ratios (SWRs, for example, the 20% SWR refers to D/Bs= 0.2, where D is slot width and Bs is the width of two decks) may exhibit different flutter performance [4,5].…”

Section: Introductionmentioning

confidence: 99%

Flutter characteristics of twin-box girder bridges with vertical central stabilizers

Yang

Zhou

et al. 2017

Engineering Structures

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It has been well known that Vertical Central Stabilizers (VCS) have the potential of improving flutter performance of long-span bridges. However, the fundamental flutter mechanisms of VCS are still not fully understood so far. In this study, a series of windtunnel tests involving the combination of six representative heights and four types of VCS were conducted to fundamentally investigate the influence of VCS on flutter performance of twin-box girders with various Slot Width Ratios (SWRs). Experimental results show that the flutter instability of 20% SWR is significantly sensitive to the height change of VCS, whereas the VCS have little effect on the flutter performance for 80% and 100% SWR. In addition, the results from Two-Dimensional Three Degree of freedom (2D-3DOF) flutter analysis demonstrates that aerodynamic damping Part A with reference of flutter derivative A2 * makes the greatest contribution to the flutter instability for a 0.8 h/H VCS, while the role of Part D with reference of A1 * H3 * becomes critical for a short VCS (i.e. the ratio of h/H is less than 0.2). Besides, the results of Computational Fluid Dynamics simulation indicate that the geometry of VCS influence the transforming vortices' structures and pressure distribution under the central slotting. Finally, the modified Selberg formula presented in this study has the capability of predicting the critical flutter speed of twin-box girders with various SWRs and VCS.

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“…However, due to cost considerations, the ratio of the gap width to the single deck width is normally set to be smaller than 1.0 (Trein et al, 2013). Keeping in mind that flutter stability improves with the gap width increase, it is likely that the vortex shedding mechanism is also affected by the change of the gap width.…”

Section: Re Effects On Vortex Sheddingmentioning

confidence: 99%

Large-Scale Testing to Study the Effects of Critical Parameters on the Aerodynamic Behavior of Long Span Bridges

Kargarmoakhar¹

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All rights reserved.iv DEDICATION This dissertation is dedicated to my wife, Maryam Asghari Mooneghi. There is an old quote saying that "No man succeeds without a good woman behind him". I should say that this is more than true in my case. My wife not only was my support as my best friend during my career, let me share with her the difficulties I faced and helped me relax, but also was a great scientist with whom I was able to discuss about challenging problems. There were some days I was near to a complete surrender, but her sacrifices let me stand up again and continue the way. I am always grateful to my wife, not only as my wife but as my closest friend and I want to thank her for her supports during the precious time that we spent together at FIU and at Wall of Wind to get our PhDs. Wind tunnel testing is a well-established practice to evaluate the stability of bridges against wind loads. In order to study the response of the prototype in laboratory, dynamic similarity requirements should be satisfied. One of the parameters that is normally violated in wind tunnel testing is Reynolds number. In this dissertation, the effects of Reynolds number on the aerodynamics of a double deck bridge were evaluated by measuring fluctuating forces on a motionless sectional model of a bridge at different wind speeds representing different Reynolds regimes. Also, the efficacy of vortex mitigation devices was evaluated at different Reynolds number regimes. Not only the flow properties play an important role on the aerodynamic response of the bridge, but also the geometry of the cross section shape is expected to have significant effects. In this dissertation, the effects of deck details, such as width of the gap between the twin decks, and traffic barriers on the aerodynamic characteristics of a twin deck bridge were investigated, particularly on the vortex shedding forces with the aim of clarifying how these shape details can alter the wind induced responses.

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On the effects of the gap on the unsteady pressure characteristics of two-box bridge girders

Cited by 18 publications

References 28 publications

Wind Tunnel Study on the Effect of the Gap Width in the Aerodynamic and Aeroelastic Responses of Twin-Box Decks

Wind Tunnel Study on the Effect of the Gap Width in the Aerodynamic and Aeroelastic Responses of Twin-Box Decks

Flutter characteristics of twin-box girder bridges with vertical central stabilizers

Large-Scale Testing to Study the Effects of Critical Parameters on the Aerodynamic Behavior of Long Span Bridges

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