Fracture mechanics assessment of fatigue cracks in offshore tubular structures

This report describes the development of new equations for calculating stress intensity factors (SIFs) for semi-elliptical weld toe cracks in T-butt joints and illustrates the use of the equations for fatigue assessment of tubular joints. Numerical modelling of 3-D T-butt joints, SIF and Mk factor evaluation, and the results of a parametric analysis are discussed along with the development of new Mk (weld toe magnification factor) factor equations, assessment and validation of the regression equations. Comparisons with existing Mk/SIF solutions and tubular joint SIFs are examined, and fatigue crack growth calculations using the new SIF solutions are presented. A database of Mk factors and new Mk factor solutions are provided in the appendices.