Axial Capacity of CHS T-Joints Reinforced with Welded External Stiffeners Under Load

Abstract

Steel Circular Hollow Section (CHS) joints have been extensively utilized in construction. Current research mainly focuses on joints reinforced in unloaded states, reinforcement under load less commonly addressed. This study examines the mechanical behavior of CHS T-joints through an experimental analysis of six specimens, each featuring varying brace-to-chord diameter ratios (β), welded under different load factors. Identified primary failure modes of the joints are local buckling and out-of-plane inclination. Furthermore, a thermo-mechanical coupling finite element model, considering the material addition during the welding process, was developed to investigate the influence of the welding under load. The results indicate that welding under axial load has little effect on the ultimate loading capacity of the CHS T-joints. Notably, welding-induced residual deformation on the chord surpasses that on the brace, particularly when welding passes are proximal to the brace-chord intersection. Residual stress in welds is not significantly affected by the stress in the tubular; only the stiffeners near the welds are affected. Despite some joints exhibiting out-of-plane inclination, the enhancement in ultimate bearing capacity exceeds 24%.