Experimental study on concrete-filled double-skin circular steel tubes under combined loadings

Totally five concrete filled double-skin circular steel tubes with various shear span ratios and axial force ratios were tested under compression-bending-shear loading conditions. The test results show that the stiffness and the load carrying capacity of the specimens decrease with the shear span ratio increasing. The load carrying capacity of the specimens with axial force ratio of 0.15 is little higher than that of specimens without axial force, while the axial force ratio nearly has no effect on stiffness. The load-deformation curves of the concrete-filled circular steel tubes show good agreement with those of double-skin specimens. The load-deformation curves of all specimens were also numerically calculated by finite element software ABAQUS. The numerical results are found to be in good agreement with test data. The mechanical performance of the specimens with respect to the influence of axial force ratio and void ratio on the response of the load-deformation curves and load distribution between steel and concrete was analyzed and compared with each other. The parametric study results indicate that the shear loading capacity first increases and then decreases with the axial force ratio changing from 0 to 0.8. The shear loading capacity decreases with the void ratio changing from 0 to 0.75. ©, 2015, Jianzhu Jiegou Xuebao/Journal of Building Structures. All right reserved.