Shakedown analysis of CHS T-joints

Recent studies at Monash University have shown incremental collapse failure of CHS KT- and YT-joints occurring at loads of up to 18% below the static strength of the joint. Incremental collapse occurs when the joints are subjected to high amplitude, low frequency loads. Current research aims at predicting shakedown failure loads for these joints using the Upper Bound Theorem of Shakedown. This theorem requires an envelope of elastic response of the structure to all load cases, and a kinematically admissible strain rate. The kinematically admissible strain rate is basically a valid collapse mechanism and can be quantified using yield line analysis, and the elastic response can be determined using finite element analysis. This paper looks at predicting the shakedown load of a T-joint undergoing variable axial loading and in-plane bending moment applied to brace.