Strength Reduction Factors for Cracked Multi-planar Tubular DT-joints

Abstract

This paper reports the strength reduction factors of cracked multi-planar tubular DT-joints subjected to three simple loadings. The three strength reduction factors are used to calculate the static strength of the cracked tubular DT-joints and they have never been reported in any reference. Mesh of the cracked tubular DT-joints is created using a set of mesh generation code, and then FE (Finite Element) analyses are carried out using commercial software. The strength reduction factor is defined as the ratio of the static strength of the cracked joint over the uncrack joint. The effect of the crack area on the static strength of tubular DT-joints is investigated prudently. It is found that when the crack area is 25% of the product of chord thickness and weld length, the static strength of the cracked tubular DT-joint can decrease more compared to the corresponding uni-planar tubular T-joint, and the decrease magnitude is up to 23.2%, 37.4% and 31.2% of the static strength of the uncracked tubular DT-joint for axial tensile, IPB (In-Plane Bending) and OPB (Out-of-Plane Bending) loading, respectively. Finally, based on the FE results, three linear equations are recommended for calculating the strength reduction factors of cracked tubular DT-joints.