Finite Element Analysis of RHS T-Joints

The finite element method (FEM) is used to model the behavior of rectangular hollow section (RHS) T-joints beyond the elastic limit, and is applied to determine their ultimate and working strengths. Punching shear and rotational stiffnesses under branch axial force and bending moment have also been calculated. The unreinforced and haunch type joints were analyzed in the study. In both cases the chord top flange was modelled as a thin plate supported by coupled edge springs. Loading was incorporated through line loads along the perimeter of a rigid inclusion (the branch). In the elastic range, joint stiffness values were found to be in good agreement with the available test results. The sensitivity of joints to different geometric parameters, i.e., width ratio λ, haunch size λ₁, and chord thickness t was studied using the FEM model in the elastic-plastic range. Ultimate branch moments or punching shear forces were found to be about five times the corresponding first yield values, thus indicating the need to base design loads on an ultimate strength or maximum deflection criterion.