Ultimate capacity of bulge formed T-joints under brace axial compressive loading

An innovative tubular joint reinforced by a bulge plate was proposed for the first time, named the bulge formed joint. Different from the unstiffened joint, an additional bulge plate is employed to connect the braces and the chord. To investigate the ultimate capacity, firstly full scale experiments and finite element (FE) analyses were conducted for a bulge formed T-joint and its counterpart (an unstiffened joint). Verified by test, the FE method was used to investigate the ultimate capacity of more bugle formed T-joints under brace axial compressive loading. Totally 190 FE models of the bulge formed T-joints and 146 FE models of the unstiffened joints (the counterpart) were analyzed. As a result, four failure modes were found for the bulge formed T-joints, and the ultimate capacity of the bulge formed T-joint was proved to be increased up to 200% compared with that of the unstiffened joint. Finally, the effects of geometrical parameters (τS, η1, η2, α, β, γ and τ) on the ultimate capacity were discussed, among these geometrical parameters, the first three are particularly defined for the bulge plate, while the other four are same as those of the unstiffened joint.