Unsteady galloping of a bridge deck with open cross section: Wind tunnel tests and mathematical modeling

Galloping instability can potentially threaten the modern launching of steel-concrete composite bridge girders, due to light weight and bluff shape of the normally first-launched steel box. A bridge deck with typical open cross section was selected and investigated in smooth flow through wind tunnel techniques. Aeroelastic tests showed that the classical instability arising from the interaction between vortex-induced vibration (VIV) and galloping may occur for a flow incidence of 4°. In contrast, a different and more complicated behavior was observed for a null wind angle of attack. Static tests further indicated that the most evident difference between the two cases is the magnitude of the vortex shedding force, which is much lower for a null an-gle of attack. Finally, Tamura’s wake-oscillator model was implemented for the bridge deck at a flow incidence of 4°, following a recently proposed parameter identification method. The mathematical model was found to be able to give some promising predictions even for a com-plex bridge deck profile.