Behaviour and design of demountable CFST column-column connections under tension

In the current construction practice, concrete-filled steel tubular (CFST) columns are difficult to be dismantled and relocated due to the continuous infilled concrete and reinforcement inside the columns. An innovative design method of the connections for CFST columns has been proposed herein, with which the CFST columns can be easily dismantled and reused. This study presents the experimental results on two demountable CFST column-column connections under eccentric tension. The initial stiffness, ultimate tensile strength, demountability as well as the post-peak behaviour is investigated. The present paper also develops a finite element model for the prediction of the tensile behaviour of the demountable CFST column-column connections. In the developed numerical model, the fracture of steel tubes under tensile loading and the failure of blind bolts due to shear force can be well simulated. Furthermore, a series of parametric studies have been carried out with the validated finite element model. Finally, the predictions from the finite element analysis were further compared with Australian Standard AS5100, and it was found that the practice code is slightly conservative in terms of the strength prediction and is safe to be used in engineering practice.