Safety Assessment Procedure for a Cracked Square Hollow Section (SHS) Y-joint

In this paper, an accurate crack model of a square hollow section (SHS) welded Y-joint is proposed, and a high quality finite element mesh is generated. Based on this numerical model, the load-displacement curves and the stress intensity factors (SIFs) along the crack front are calculated. It is shown that the highest value of the stress intensity factor is always located at the chord corner. From the full-scale static strength test carried out on the cracked SHS Y-joint, it was found that ductile crack tearing initiated at the crack front parallel to the chord side wall where the fracture toughness is smaller, and not from the crack front around the corner where the SIF is the highest. Using the plastic collapse load obtained via the twice elastic compliance technique and the fracture toughness obtained from the Charpy V-notch and CTOD tests, the assessment points of Kr and Lr are calculated and plotted on the BS7910 (2005) Level 2A Failure Assessment Diagram (FAD) curve, thus demonstrating its usage. It...