Failure mechanisms of tubular CHS joints with complete overlap of braces

This paper presents the experimental and numerical results of the ultimate load behaviour of tubular circular hollow section (CHS) joints with complete overlap of braces. A completely overlapped tubular CHS joint specimen is tested to failure under lap brace static incremental axial loading. The failure behaviour of the joint is carefully observed and the test result is used for the verification of finite element (FE) model. A detailed parametric study is subsequently conducted based on 1296 FE models to examine the failure modes and the load-deformation characteristics of the joint. The analytical results showed that there are four possible failure modes of the joint under lap brace axial compression namely the through brace wall plastification, the lap brace yielding, the lap brace local buckling and the lap brace member failure. A combination of these failure modes can be occurred depending on the geometrical parameters of the joints. Among these failure modes, the through brace wall plastification in contact with the lap brace is found to be the most common type of failure behaviour for joints with complete overlapped of braces at high lap brace-to-through brace wall thickness ratio.