Concrete-filled steel tubes with reinforcing bars or angles under axial tension

A series of tests on concrete-filled steel tubes (CFSTs) with reinforcing bars or angles under axial tension were conducted in this study. In total, thirteen full scale specimens having length of 4000 mm and outer diameter of 400 mm were tested. The steel tubes were fabricated from structural steel with nominal yield strength of 460 MPa and nominal plate thickness of 4 or 6 mm. Reinforcing bars or angles were placed inside the steel tube before the filling of concrete. The behaviour and strengths of CFSTs with reinforcing bars or angles under axial tension were investigated. The load-axial displacement curves and load-strain curves were obtained. The cracks in the core concrete were also investigated from the failure specimens. The tensile strengths are compared with the design strengths calculated using the current AISC standard. Design equations were proposed for the tensile strengths and elastic tensile stiffness of CFSTs with reinforcing bars or angles.