Buckling behavior of closed-ribs orthotropic steel decks in long-span suspension bridges

Recently, routine inspections of existing orthotropic steel decks (OSDs) have revealed numerous instances of local buckling deformations in the U-ribs, which could significantly affect the structural safety of the bridges. Therefore, this study aims to investigate the buckling behavior of OSDs with closed ribs and to figure out the effect of major parameters on buckling strength. Nonlinear FEA considering the geometric and material nonlinearities has been carried out on a long-span suspension bridge with reported severe local buckling failure on its OSD. The effects of initial geometric imperfection, residual stress, and traffic loading have been analyzed and compared. The significance of using UHPC overlay as a repairing strategy for the interest bridge has been revealed. Results indicated that local buckling behavior of the closed ribs showed a sudden drop in the loadcarrying capacity after reaching its peak, posing a significant threat to its stability. Initial geometric imperfections and residual stresses also significantly affect the buckling strength. FEA considering the bridge current conditions showed 27.0% reduction in the buckling strength which could endanger its stability in the future operation. Using UHPC overlay remarkably enhanced the buckling strength of OSD and hence it is strongly recommended to be used to rehabilitate the working bridge under consideration.