Experimental Study of Concrete-Filled Double-skin Circular Steel Tube Subjected to Pure Torsion

Six concrete-filled double-skin circular steel tubes and one double-skin hollow circular steel tube were designed and tested under pure torsion load.The primary parameters in the experiment are the nominal steel ratio,the steel strength of outside tube and the hollow ratio.Experimental results show that steel tubes work together with concrete and they are deformed harmoniously in loading process.All specimens present good plasticity.The greater nominal steel ratio and steel strength are,the greater torsional capacity is.The higher the hollow ratio is,the greater the torsional capacity is.The torsion capacity of concrete-filled double-skin circular steel tube is significantly improved comparing with double-skin hollow steel tube.Torque-angle relation curve of concrete-filled double-skin steel tube subjected to pure torsion was analyzed by using finite element software ABAQUS.Calculation results are in a good agreement with experimental results.