Abstract
The aerodynamic performance of bridge deck girders requires a thorough assessment and optimization in the design of long-span bridges. The present paper describes a numerical investigation of the aerodynamic characteristics of a twin-box bridge girder cross section in the range of angles of attack between −10.0° and +10.2°. The simulations are performed by solving 2D unsteady Reynolds-averaged Navier–Stokes (URANS) equations together with the k–ω shear stress transport (SST) turbulence model. The investigated Reynolds number (Re) based on the free stream velocity ( U ∞ ) and the height of the deck (D) is 31,000. The predicted aerodynamic characteristics such as the mean drag, lift and moment coefficients, are generally in good agreement with the results from the wind tunnel tests. Changes of flow patterns and aerodynamic forces with different angles of attack are investigated. Flow characteristics during one vortex shedding period are highlighted. Relative contributions of each of the two bridge decks to the overall drag and lift coefficients, with respect to the angle of attack, are also discussed.
Highlights
In wind-resistant bridge design, many factors should be considered, such as static wind load, wind forces due to turbulence, aerodynamic instability and vortex-shedding excitation
For bridge spans around 1 km and longer, twin-box girders are being increasingly used, due to their favorable aerodynamic properties in term of flutter stability. This is due to a favorable effect of the central gap on the surface pressure distribution, and a higher ratio between the twisting and the heaving eigen-frequencies [1,2]. This configuration is prone to vortex-induced vibration, since vortices shed from the windward box can cause a significant excitation of the leeward box and thereby important oscillations of the bridge girder [3,4]
An increase of the projected area in the cross-flow direction. It appears that the present 2D RANS simulations with the k–ω stress transport (SST) turbulence model are in satisfactory agreement with the experimental data under the same flow conditions, especially at small angles ofHalsafjord attack (AoA)
Summary
In wind-resistant bridge design, many factors should be considered, such as static wind load, wind forces due to turbulence, aerodynamic instability and vortex-shedding excitation. Several studies of flow characteristics the comparable results in terms of accuracy of first and second order pressure statistics measured the sharp-edged twin-boxes, with asymmetric geometry as in the present case, haveatbeen central section of the These considered prism. Studies haveThe mainly dealt with the overallofflow conditions and their small angles of attack were under-estimated by LES as compared to simulations, and the variations with the relative gap size, Reynolds number and turbulence models used in the experimentalTo data between them generally. The cross-section geometry with asymmetric geometry as in the case, have out [22,23,24] These and the Reynolds number in the simulations are present adopted as forbeen the carried section model, which was studies have mainly dealt with the overall flow conditions and their variations with the relative gap exposed to a uniform flow.
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