EXPERIMENTAL STUDY ON BEARING CAPACITY FOR CIRCULAR TUBULAR T-JOINTS WITH COLLAR PLATE REINFORCEMENT

For a circular tube member, its radial stiffness is generally much smaller than its axial stiffness due to its hollow section and thin wall. In a welded tubular joint, the brace is mainly subjected to axial loading, and thus makes the chord be subjected to radial loading. Furthermore, high stress concentration exists at the joint because the curvature is not continuous. Due to the above reasons, the common failure mode for a tubular joint is the local yielding or buckling on the chord surface near the weld toe. To improve the bearing capacity of a tubular joint, a collar plate is welded around the weld toe to increase the radial stiffness of the chord, and thus to increase the static strength of the joint. Through experimental tests on the static bearing capacity of 3 un-reinforced and 3 collar plate reinforced tubular T-joints under axial compression, the reinforcing efficiency is verified. The experimental results show that the failure mode and the failure position are both changed due to the reinforcement of the collar plate, and the collar plate improves the static strength of the T-joints remarkably.