Experimental and Analytical Investigation of the Reynolds Number Effect on Wind Forces for Multi-Girder Bridges

Long-span bridges are flexible and therefore are sensitive to wind induced effects. For investigating the response of a bridge under wind loads using wind tunnel testing, aerodynamic similarity requirements should be satisfied. One of the parameters that is normally violated in wind tunnel testing is Reynolds number. The effect of Reynolds number can be amplified on multi–girder bridges. For investigating the effect of Reynolds number on the vortex shedding for modern bridges, a 2D section of a twin-deck bridge is evaluated analytically using computational fluid dynamics (CFD) and the results are compared with experimental results from large-scale tests performed in the Wall of Wind facility at Florida International University. CFD analysis was performed using vortex discrete method. Based on the results from this study, a similar trend is observed for the Reynolds sensitivity between the experimental and numerical results. Both methods show a reduction in the drag coefficient with the Reynolds increase up to 4×10⁶. However, with the additional increase of Reynolds, drag coefficient increases.