STUDY ON STATIC STRENGTH OF TUBULAR JOINTS REINFORCED WITH VERTICAL INNER PLATE

The stiffness of the chord in radius direction is much weaker than that of the brace members in axial direction, as a result, failure occurs easily at the weld toe on the chord surface when a tubular joint is subjected to static loads. To improve the bearing capacity of tubular joints, the vertical inner plate can be placed inside the chord to increase the stiffness of the chord. Using the finite element method, overall 33 T-joint models with or without reinforcements are modeled and analyzed, and the stress development of the inner plate and the joint region is investigated. It is found from the parametric study that the length of the inner plate has great influence on the static strength of joints. The ultimate strength of a tubular joint increases remarkably as the length of the vertical inner plate increases. However, the growth rate of the static strength becomes much slower after the length of the inner plate exceeds certain values. Basically, the thickness of the inner plate has less effect on the improvement of the static strength of a tubular joint, yet it can not be too small to prevent buckling. At last, 24 geometrically different T-joints with or without vertical inner plates are analyzed, and the strengthening effect is evaluated through a comparison between the unreinforced model and the reinforced model.