Fatigue strength assessment of complex welded structures with severe force concentrations along a weld seam

•Full-scale fatigue tests for a complex welded connection with failure at the weld root.•Tests included fatigue failure with different structural details and weld types.•Crack propagation was visually observed.•The results were analysed with three stress-based local approaches.•Among them, the local nominal weld stress approach resulted in the smallest scatter. This paper investigates weld root fatigue strength of complex structures including severe force concentrations along a weld seam. Fatigue tests were carried out for a pillar assembly with various weld configurations. A comparative analysis was carried out with local nominal weld stress (LNWS), structural weld stress, and effective notch stress (ENS) approaches. The study shows that the LNWS approach gives the best prediction, with a scatter range index of 1.26 to 1.68 depending on the weld type. The accuracy of the structural weld stress approach and ENS was significantly lower, with a scatter range index of 4.98 and 5.40, respectively.