A new orthotropic steel deck system incorporating two novel structural details

Abstract

The fatigue and fracture of orthotropic steel decks (OSDs) have compromised the toughness and life of steel bridge. The low fatigue resistance of structural detail design is the primary factor to result in the fatigue fracture of OSDs. To develop OSDs with a high fatigue resistance, two novel structural details for OSDs including rib-to-deck welded joint and rib-to-floorbeam welded joint were proposed in this study. Novel rib-to-deck welded joint was formed with a double-side fillet weld seam, which improves the fatigue performance of rib-to-deck welded joint by eliminating the crack-like defects at the weld root of traditional rib-to-deck welded joint. Novel rib-to-floorbeam welded joint is proposed with an uninterruptible weld seam and a smiley cutout, which relieves the cyclic stress from out-of-plane bending of floorbeam and transfer the potential large stress ranges from the weld seam to the smiley cutout. The comparisons of traditional and novel structural details were carried out by the finite element analysis and fatigue tests. The nominal stress method was used in this study to evaluate the fatigue performance. The results indicate that fatigue resistance corresponding to 2 million cycles (FAT) of novel rib-to-deck welded joint is higher than the traditional rib-to-deck welded joint (FAT = 95 MPa), and FAT of novel rib-to-deck welded joint is over 116 MPa. The fatigue strength of the novel rib-to-floorbeam welded joint with a smiley cutout (FAT > 140 MPa) is higher than that of traditional rib-to-floorbeam welded joint (FAT = 98 MPa). The proposed novel structural details can be effective to improve the fatigue resistance of OSDs.