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 (beta) and layouts of BDGs were made, and then the force- and vibration-measured tests were performed to study the influence of the layouts and beta of BDGs on the aerostatic and flutter stability. Furthermore, the influence mechanism of BDGs on the flutter stability was investigated, and the optimal beta and layouts of BDGs were also proposed. So, it is found that: when 0% <= beta <= 22% (especially beta = 11%), BDGs are unfavorable to the aerodynamic stability; when beta >= 44%, the aerodynamic stability can be significantly improved by using BDGs; moreover, the layouts of Cases O (beta reaches the maximum) and S (two strips of BDGs installed along the longitudinal direction) are more beneficial to the aerodynamic stability. Therefore, the optimal beta and layouts of BDGs beneficial to the aerodynamic stability are beta >= 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.