Aerodynamic instability of a hinged-deck cross-section cable-stayed bridge

An experimental investigation of instabilities of a cable-stayed bridge using wind tunnel tests is considered. The bridge deck is composed of three parts: the central deck, and two extensions, one at each side. These extensions can rotate around hinges placed at the central deck edges. The central deck and the extension decks are supported by their respective cable system. Performing a sectional test of a rigid bridge section only two DOF should be considered. However, here, 6 DOF should be considered in the modelling of the elastic problem. This is a reduced model based on a FEM model of the whole bridge, and is the base for the design of the wind tunnel tests. Aeroelastic tests have been performed in the IDR ACLA-16 wind tunnel. The influence of the angle of attack of the windward extension deck on the bridge stability has been studied. The complexity of the bridge deck motion is described considering both the oscillation frequencies and the modal shapes. Stability ranges are presented in terms of reduced wind speed and compared to other long span bridges. In a configuration, the stability range achieved is more than twice that of a similar bridge.