Insights into the nose-up effect on the Çanakkale twin-box bridge deck based on CFD simulations

This study explores the nose-up effect on the 1915 Çanakkale twin-box bridge deck, using CFD simulations to analyze the role of gantry rails. Previous work established that gantry rails influence the aeroelastic stability of the bridge by altering the pitching moment from negative to positive at a 0◦ angle of attack, which encourages a nose-up rotation of the deck and enhances flutter stability. This research investigates why aerodynamic derivatives decrease with increasing angle of attack and how specific flow patterns contribute to this behavior. 2D stationary CFD simulations were conducted for two configurations– with gantry rails (C1) and without (C2)– using URANS and the k-ω SST turbulence model. The simulations were validated against experimental lift and moment coefficients within an angleof-attack range from-3◦ to +4◦. Key findings reveal that, in C1, gantry rails impact flow separation and vortex behavior, contributing to lower local lift derivative at higher angles. In C2, where gantry rails are absent, these changes are reduced. Ultimately, the gantry rails contribute to a reduction in lift and moment coefficient slopes, and during the conference, a detailed comparison of C1 and C2 will be presented to further clarify these effects.