Effect of Stabilizer Plate Dimensions on Flutter Optimization of Truss Girder at Large Angles of Attack

Aerodynamic stabilizers have been widely applied to enhance the flutter performance of long-span bridges. This study investigates the flutter behavior of the girder of a mountainous long-span truss-suspension bridge. It also analyzes the effects of stabilizer plates with different geometric parameters on the optimization of girder flutter performance under large angles of attack (AoA). Wind tunnel tests indicate that, at high AoA, the flutter performance of the truss girder increases with the height of the upper central stabilizer. For horizontal stabilizers, there exists an optimal width at which the girder achieves the best flutter performance. Flutter derivatives under various conditions were obtained through forced vibration tests, and the mechanism by which stabilizer parameters enhance girder flutter performance was analyzed using the work done by self-excited moments. As the height of the central stabilizer increases, the wind speed corresponding to the transition of the self-excited forces from negative to positive continuously rises. In contrast, as the width of the horizontal stabilizer increases, the corresponding wind speed first increases and then decreases, indicating the existence of an optimal width that maximizes flutter performance. Finally, computational fluid dynamics (CFD) simulations were conducted to examine the flow field around the truss girder. The results show that increasing the central stabilizer height leads to a more uniform vortex distribution above the bridge deck, while increasing the horizontal stabilizer width causes premature flow separation. At the optimal width, flow separation prevents vortices beneath the deck from attaching behind the chord members, thereby enhancing aerodynamic stability.