Effects of boundary conditions and chord stresses on static strength of thick-walled CHS K-joints

This paper presents results from a systematic investigation on the static strength of thick-walled circular hollow section (CHS) K-joints with various boundary constraints and chord axial stresses. The effects of boundary conditions appear to be critical if the boundary constraints alter the chord stress level. A K-joint with unconstrained brace ends is observed to indicate a rapid decrease in the post-peak joint strength. For a joint with members (brace and chord) of sufficient length, the member end fixities impose marginal effects on the joint strength. It is found that displacement-controlled loads on an isolated K-joint provide a realistic representation of the load distribution of a K-joint within a tubular frame. A definition in terms of maximum chord stress ratio for a new chord stress function for K-joints is found to minimize the scatter with respect to variations in the joint geometry.