Failure assessment of a cracked circular hollow section T-joint including the effect of crack-front constraints

Abstract

This paper describes a procedure using the Failure Assessment Diagram (FAD) concept outlined in BS7910, to assess the interaction between the fracture failure and the plastic limit action for a Circular Hollow Section (CHS) T-joint with an initial semi-elliptical flaw, which was reported in a series of experimental investigation. The FAD approach applies the constraint-modification based on a linear-elastic T-stress computed along the front of the semi-elliptical surface crack, to the level 2A assessment curve in BS7910. The assessment of the fracture ratio K r utilizes the material fracture toughness reported in the experiment, while the load ratio L r compares the latest T-joint ultimate strength formulation in the IIW recommendations and the experimentally measured ultimate joint strength. The failure assessment outcome, both with constraint modification and without constraint modification, proves to be conservative compared to the experimental measurement on the T-joint. © 2010 The University of Hong Kong.