Analysis of the Ultimate Strength of a New J-type Stiffened Orthotropic Steel Bridge Deck

Abstract

To address the fatigue issue of U-rib orthotropic steel bridge decks under vehicle loading, a novel J-type stiffening rib (J-rib) structure is introduced. The structure consists of a vertical straight section and a bottom semi-arc, with a deck thickness and height comparable to those of the U-rib. The moment of inertia about the transverse axis is similar; however, the opening design facilitates welding and can significantly enhance the fatigue strength. Due to the asymmetric open section of the J-ribs, existing design codes do not provide adequate design methods. This study investigates a bridge deck with thickness ranging from 14 to 20 mm and a crossbeam spacing between 1500 and 3000 mm. Using ANSYS software, axial load-bearing capacity analysis was conducted to investigate characteristics such as load-bearing capacity, deformation patterns, and plastic zone distribution. A bearing capacity calculation method is proposed based on the stability theory of compression members. Furthermore, the combined compressive and flexural analysis indicate that the influence of vertical loads on the structural bearing capacity is relatively minor. Fatigue life comparisons suggest that the J-rib is theoretically expected to exhibit infinite fatigue life.