Static Strength of Tubular T-Joints with Reinforced Chord under Axial Compression

A typical tubular T-joint is made up of a chord member and a brace member, and the brace member is connected to the chord surface with full penetration welds. As the stiffness of the chord in the radial direction is much weaker than that of the brace member in the axial direction, failure occurs easily at the weld toe on the chord surface when the chord is subjected to static axial load in the brace axial direction. To improve the static strength of a tubular T-joint, the chord near the weld toe can be reinforced locally by increasing its thickness. To study the effect of the chord reinforcement on the static strength of a tubular T-joint, 48 T-joint models with different reinforcements have been analyzed using the finite element method. The effects of the chord thickness and the length of the reinforced chord on improving the static strength of tubular joints have been investigated. It is found that the static strength can be greatly improved by increasing the chord thickness near the intersection. However, the increased chord thickness should not be much greater than the original chord thickness to avoid changing of the failure mode. On the other hand, it is not effective to improve the static strength by increasing the length of the reinforced chord. The effects of the geometrical parameters and the chord thickness on the static strength of the T-joints are also studied parametrically by analyzing another 240 T-joint models. Finally, a parametric equation is presented, and its accuracy in predicting the static strength of the tubular T-joint subjected to axial compression is verified through error analysis against the numerical results.