Experimental investigations on the influence of bridge deck gratings on the aerodynamic stability of the long-span suspension footbridge with a streamlined double-side box girder

In the complex wind environment of canyon regions, different kinds of bridge deck gratings (BDGs) are often used as novel aerodynamic countermeasures to improve the wind-resistance performance of long-span suspension footbridges. However, how to design reasonable BDGs to effectively improve the aerodynamic stability of long-span suspension footbridges is still an urgent problem to be solved, and there is no literature reporting on it. Therefore, in this study, according to a long-span suspension footbridge with a streamlined double-side box girder (SDSBG) and BDGs, the section models with different percentages of opening (β) and layouts of BDGs were made, and then the force- and vibration-measured tests were performed to study the influence of the layouts and β of BDGs on the aerostatic and flutter stability. Furthermore, the influence mechanism of BDGs on the flutter stability was investigated, and the optimal β and layouts of BDGs were also proposed. So, it is found that: when 0% ≤ β ≤ 22% (especially β = 11%), BDGs are unfavorable to the aerodynamic stability; when β ≥ 44%, the aerodynamic stability can be significantly improved by using BDGs; moreover, the layouts of Cases O (β reaches the maximum) and S (two strips of BDGs installed along the longitudinal direction) are more beneficial to the aerodynamic stability. Therefore, the optimal β and layouts of BDGs beneficial to the aerodynamic stability are β ≥ 44% and the layouts of Cases O and S, respectively, and the studies in this manuscript can provide a meaningful reference for the wind resistance design of long-span suspension footbridges in the future.