Prediction of Stress Intensity Magnification Factors of a Weld Toe Crack in Load-Carrying Cruciform Fillet Welded Joints Under Axial Loading

Load-carrying cruciform fillet welded joint is commonly encountered in on-shore and offshore structures. In this study, the stress intensity magnification factors (M_km) of such configuration containing a 3-D semi-elliptical surface crack at the weld toe are analysed using 3-D finite element analyses. Due to the non-penetrating fillet welds at the intersection of the main plate and transverse stiffener, the M_km values are found to be much larger than the corresponding results of non-load-carrying cruciform welded joints. Therefore, a new set M_km equations for load-carrying joints are built up using multiple regression analyses, and statistical analyses are carried out to validate the goodness of fit of these equations. It is noted that the existing British Standard 7910 (BS 7910) assessment equation produces an over-conservative prediction on M_km values as compared with the newly proposed M_km equations, and the largest over-estimation percentage difference is as high as 257.8%.