Eccentric tensile fatigue test and crack propagation analysis of rib-to-deck weld joints

Fatigue failure of rib-to-deck (RTD) weld joints of orthotropic steel deck (OSD) is a primary factor affecting the service performance of a bridge structure. In this study, eccentric tensile fatigue tests were novelly designed and performed to approximate the combined tension-bending stress state in RTD weld joints of OSD. The optical microscope and beach marking method were used to observe the fatigue crack propagation process in the RTD weld joints, in which the fatigue crack length and depth were recorded, and the crack propagation characteristics and patterns were investigated. The numerical simulations based on the probabilistic fracture mechanics theory were then conducted to analyze the fatigue failure of the weld joints, in which a two-stage Paris model was established to describe the fatigue crack propagation process. Finally, a Monte Carlo simulation was performed for probabilistic fatigue crack propagation considering the uncertainties in initial crack size and crack propagation model. The results indicate that the proposed method has acceptable efficiency and accuracy for fatigue crack propagation and failure analysis of the RTD weld joints of OSD. • Novel eccentric tensile fatigue test specimens of rib-to-deck (RTD) weld joints were designed and tested. • Crack propagation was observed with optical microscope, achieving a minimum detectable crack length of 0.191 mm. • A two-stage Paris model was established to characterize crack propagation from microcrack to macrocrack. • A probabilistic fracture mechanics with Monte Carlo simulation accurately predicted fatigue life and crack morphology.