Study on Development and Fatigue Performance of the U-shaped Rib-to-Deck Full-Penetration Welded Joint in Orthotropic Steel Deck
Fatigue cracks in rib-to-desk welded joints of orthotropic steel bridge desks(OSD)are observed commonly,which seriously affect the service quality of bridge engineering.There is an urgent need to develop rib-to-deck welded joint with high fatigue strength.Based on advanced internal welding technology and the manufacturing technique for rib-to-deck welded joint,a high-quality welded joint with full-penetration was developed.The effects of different manufacturing conditions on the fatigue performance of the high-quality welded joint were clarified by initial manufacturing defect scale detection and fatigue life estimation,and further verified by fatigue test.The results showed that the developed high-quality welded joint have the outstanding advantages of being"defect-free and detectable".In full-penetration welding,the double-sided submerged arc welding was significantly superior to gas shielded welding,with the former only causing initial cracks at the weld toe of the deck panel,and the size of these cracks was significantly smaller than those caused by the latter.The initial micro-crack size significantly affected the fatigue life of rib-to-deck welded joints.The fatigue lifespan for initial micro-cracks of 0.05mm was twice that of a initial micro-cracks of 0.3mm.The double-sided submerged arc welding is recommended to be used as the manufacturing process of full-penetration high-quality welded joint.Fatigue test results showed that the fatigue performance of rib-to-deck full-penetration high-quality welded joint was significantly better than that of the one-side welding,partial penetration welding of both-side gas shielded welding and full-penetration gas shielded welding.