Fatigue Crack Propagation Analysis of Rib-to-deck Welded Joint in OSDs using Linear Elastic Fracture Mechanics

The orthotropic steel decks are one of the most widely used bridge decks, especially in moveable and long span bridges. Numerous cracks have been detected in existing bridges, mainly in the welded connections. Fatigue performance of the bridge decks governs the design. The crack at the rib-to-deck joint is one of the most representative types. Strict requirements of the configuration of this joint are given in design codes resulting in classification categories based on experimental findings. Fatigue life of the crack initiation and changes of the stress conditions are usually experimentally investigated. However, prediction of the crack propagation and the effect of the cracks on the local stress fields are not possible to be fully understood based on experiments only. In this paper, finite element models are refined around the crack tip using software programs Abaqus and FRANC3D to study the crack propagation of rib-to-deck joint between crossbeams. The results is compared with beach marking tests in literature. Good agreement is found between predicted results and test data for both the crack shapes and loading cycles. The largest SIF range is predicted in the middle of the developed crack. It is then moved to the position 0.19 (relative distance, normalized by the width of the specimen) away from the crack priori to the fracture. During propagation period, structural integrity is affected by the crack and stress redistribution phenomenon is observed.