Influence of distortion ratio on distortion-induced fatigue behavior of steel girder bridges

The physical fatigue test and a new proposed research methodology called the digital fatigue test are used to investigate distortion-induced fatigue performance at web gap regions in steel girder bridges. Digital fatigue test based on the extended finite element method can combine factors such as residual welding stress, initial defects, and fatigue action, to simulate the propagation of mixed-mode cracks. Physical and digital fatigue test results show fatigue strength decreases significantly with increasing distortion ratio, which is the ratio of the minimum and maximum distortion at web gaps. When distortion ratio and nominal stress ratio increased from 0.2 to 0.5, the fatigue strength of 60 mm horizontal gusset plate–vertical​ stiffener web gap and 40 mm vertical stiffener web gap decreases by 43% and 50%, respectively.