Aerodynamic countermeasures for improving flutter performance of cable-suspended bridges

This study investigates the effectiveness of various aerodynamic countermeasures in enhancing the flutter performance of cable-suspended bridges through wind tunnel experiments. Two groups of countermeasures were examined: aerodynamic attachments and bridge deck gratings. Based on closed-form bimodal flutter solutions, the flutter mechanisms of three effective countermeasures were analyzed in detail. In addition, the generalizability of these countermeasures was assessed in terms of the flutter index across different wind angles of attack (AoAs). The results demonstrate that double stabilizers installed on upper surface (case UDS), side grating (case SG), and bridge deck grating (case 30%) improved flutter performance across all wind AoAs, particularly at 3° wind AoA, where they shifted the flutter type from torsional flutter to coupled flutter, thereby significantly raising the critical flutter speed. Notably, the bridge deck grating demonstrated the potential to more than double the critical flutter speed across the tested wind AoAs. The study also finds that the flutter index can be considered constant for coupled flutter; however, for torsional flutter, it is highly dependent on reduced wind speed due to significant variation in the uncoupled term.