Capacity of steel CHS X-joints strengthened with external stiffening rings in compression

This paper studies steel circular hollow section (CHS) X-joints by conducting experiments on the axial compressive strength of unreinforced and reinforced X-joints with external stiffening rings. Three pairs of unreinforced and reinforced X-joints were tested to compare their compressive load capacity. The diameter ratios (β) between the brace and the chord β were 0.25, 0.51 and 0.73 respectively. The experimental setup, parameters and results are presented. The failure modes and load-displacement curves of the unreinforced and reinforced X-joints were compared. It was shown that external stiffening rings greatly increased the axial compressive load capacity of the X-joints, by 86%, 75%, and 58% respectively. Finite element modelling accurately predicted the structural responses of the X-joints with and without external stiffening rings.