Parametric Study and Design Formulae for the Tensile Strength of the Doubler-Plate Reinforced Square Hollow Section T-joints

Doubler-plate reinforcement is widely used to increases the strength of tubular joints. The axial tensile behavior of doubler-plate reinforced (DPR) square hollow section (SHS) joints are studied by finite element parametric analysis in this paper. The finite element model of the DPR SHS joint is established and verified using test results from literatures. Then the geometrical parameters and material properties are changed to conduct extensive parametric studies on the tensile behavior of DPR SHS T-joint, by which the brace-to-chord width ratio and the DP-to-chord thickness ratio are identified as critical parameters. The yielding or punching of the doubler-plate is found to dominate the failure of the joints, and the membrane behavior of the doubler-plate can increase the tensile strength of the DPR joints. Finally, formulae are proposed to build design equations for the tensile strength of DPR SHS joints, and a more accurate prediction is obtained comparing to EC3.