Fatigue Tests and Failure Mechanism of Rib-to-Deck Welded Joints in Steel Bridge

The fatigue cracks of rib-to-deck welded joints in an orthotropic steel deck are one of the critical conundrums that restrict the sustainable development of steel bridges. Double-sided welded joints were achieved by introducing internal welding technology to overcome the initial “crack-like” manufacturing defects at the welding roots of single-sided welded joints. Through the observation of the macro-section of the welded joint, the differences between single-sided welding, partial-penetration welding, and full-penetration welding in rib-to-deck welded joints are compared. Relying on the Shenzhen–Zhongshan link, the fatigue failure and mechanism of single-sided rib-to-deck welded joints are clarified by the nominal stress and structural stress methods, and those of double-sided welded joints were determined through fatigue tests. The fatigue strength of rib-to-deck welded joints is higher than the FAT90 of Chinese standard and the FAT C joints of American standard. The fatigue strength of double-sided rib-to-deck welded joints is significantly higher than that of single-sided welded joints. The fatigue strength of rib-to-deck welded joints is within a ± 2 σ range of main S - N curves by the structural stress method. It is suggested to adopt the double-sided welded joints in practice, and to ensure that the penetration rate is beyond 80%. The trial data are limited, and further tests are needed to confirm the results.