ABSTRACT
Aimed to study the propagation mechanism of steel bridge distortion-induced fatigue cracks, a finite element model was built to calculate the residual stresses by simulating the entire welding process of the horizontal-gusset-plate web gap detail. Numerical fracture mechanical models were built based on eXtended Finite Element Method to analyze the crack propagation behavior. The results of the welding process show that there are large residual tensile stresses at stiffener-to-web weld toes, which are close to the yield stress. Static numerical fracture mechanical analysis results show that the crack propagation modes are greatly affected by initial propagation angles, and the crack mode is Mode I leading mixed cracks of Mode I, II and III. Dynamic numerical fracture mechanical analysis shows that the detail is in the state of tension under the test loading. When the residual stress was introduced, the numerical fatigue crack propagation form is consistent with the fatigue test results, and the fatigue crack growth rate is faster.
