Behaviour and design of demountable CFST column-column connections subjected to compression

Concrete-filled steel tubular (CFST) columns exploit the advantages of both reinforced concrete and structural steel in building construction and thus have been gaining attention by designers due to their significant structural and economic benefits. In current engineering practice, CFST columns are welded along their perimeter as the connections, which render the CFST columns difficult to be dismantled and reused. This study attempts to develop an innovative design for CFST column-column connections, through which CFST columns can be dismantled readily and reused safely at the end of their service life. Furthermore, this study presents an extensive set of experimental results on demountable CFST column-column connections under axial and eccentric compressive loading. Demountability, ultimate strength capacity, stiffness and ductility for this type of connection are investigated. In addition, a series of parametric studies have been conducted in the experiment to investigate the effects of various parameters on the behaviour of demountable CFST column-column connections. The present paper also proposes a finite element model for the prediction of the behaviour of demountable CFST column-column connections. The results from the finite element analysis were compared with Australian Standards, and it was found that current design codes are slightly conservative in terms of their strength prediction and are safe to be used in engineering practice.