ABSTRACT
It is well known that rib-to-deck welded joints are one of the typical fatigue details in the steel bridge decks. The existence of cracks will pose a threat to the safe operation of the bridges. Hence, it is necessary to adopt retrofitting techniques to retard the crack growth. This paper focuses on the failure mode of weld throat cracking of rib-to-deck welds and fatigue improvement of weld throats strengthened by angle steel. Finite element models with repaired and unrepaired specimens were established to investigate the fatigue properties based on linear elastic fracture mechanics. The stress intensity factor (SIF) at the crack front was calculated and the crack propagation trend was predicted. It was demonstrated that out-of-plane bending deformation between the top plate and the U-rib is the main reason for the cracking of the weld throats. The numerical results showed that the fatigue cracks belonged to type I-dominated mixed-mode cracks, and the stress intensity factor increases with the increase of crack depth. However, bonding angle steel can reduce the effective stress intensity factor range to prolong the fatigue life of the cracked weld throats. The stress intensity factor could be reduced by 80% to 97% after repairing. And fatigue crack propagation can be further arrested when strengthening in the early stage of crack initiation. The predicted crack propagation behavior was almost consistent with the experimental results, and the angle between the propagation path and the top plate was between 30° and 45°.
