Refined fatigue assessment of joints with welded in-plane attachments by LEFM

• The fatigue life of a welded in-plane joint is studied using LEFM.
• An empirical expression for the stress magnification factor Mk is derived.
• Fictitious crack depths are used to derive the fatigue strength.
• A numerical example shows a significant increase in fatigue life.

The fatigue life of joints with welded in-plane gusset plates is studied. The purpose is to suggest a descriptive detail category to be used in assessment of existing structures. Linear elastic fracture mechanics is used together with fictitious initial crack depths to predict the fatigue life. By calibrating the fictitious crack depths to real fatigue tests and simulating new test results, fatigue strengths dependent on the dimensions of the joint have been derived. The results show that a decreasing length and thickness of the gusset give decreasing stress intensity and higher fatigue strength. A numerical example is presented showing the merit of the proposed strengths in fatigue life.