Tests of CHS T-joints with convex chord under axial compression

An experimental investigation was conducted on circular hollow section (CHS) T-joints with convex hollow and concrete-filled steel tube (CFST) chord under axial compression. A total of 16 specimens was fabricated by hot-rolled bending the chord members into curvature with three different radii to apply axial compression force to the brace members, in which 6 specimens were tested with convex hollow chord, 6 specimens were tested with convex CFST chord, and 4 traditional CHS T-joints with straight hollow and CFST chord were also tested for comparison. The joint strengths, failure modes, axial load-vertical displacement curves, axial load-chord deformation curves and strain distribution curves of all specimens are reported. It is shown from the comparison that the ultimate strengths of the CHS T-joints with convex chord are generally larger than those of the traditional CHS T-joints with straight chord. Furthermore, the ultimate strengths of traditional CHS T-joints with straight chord are significantly enhanced by filling the concrete in the chord member only. Whereas, the enhancement of the ultimate strengths of CHS T-joints with convex chord by filling the concrete in the chord member only is quite small.