Ultimate capacity of completely overlapped tubular joints: I. An experimental investigation

This paper presents the experimental finding of a full-scale completely overlapped joint tested to failure under lap brace axial compression. The failure mode of the joint was due to the through brace face plastification. An ovalising effect of the through brace cross-section and bending on the gap region were noted. The onset of non-linear behaviour occurred at 72% of the ultimate load. The capacity of the joint was found to be 7.3% higher than that of the simple gap K-joint, which was determined from the ultimate strength formula. The deformation limit of the joint was 3.82 times the lap brace yield deformation. In the numerical study, the 8-node thick shell element was used to model the joint. No weld element was modelled, but the material with strain hardening property was necessary in the model. The comparison of the load–displacement curve with the experimental results showed a reasonably good agreement, with 5% less for both the ultimate load and the corresponding lap brace axial displacement. As the finite element method was verified to be reliable and accurate, a detailed parametric study was performed to intensively investigate the ultimate load behaviour of the completely overlapped joint as described in the companion paper on behavioural study.