Experimental research on axial compression performance of medium-and-long steel tubular columns filled with high-strength self-stressing self-compacting concrete

The steel tube filled with high-strength self-stressing self-compacting concrete is proposed to improve the compactness, reduce the shrinkage of the core concrete and enhance the working performance of steel tube and concrete in practical engineering. 16 specimens are designed and manufactured with consideration of influential factors such as initial self-stress, slenderness ratio and concrete strength. By the axial compression tests, the failure patterns of the specimens are investigated. The load-deformation curves, load-deflection curves and the ultimate load-bearing capacity are measured and the influence of different factors is analyzed. The results show that most specimens demonstrate a buckling failure pattern. When the initial self-stress increases to 5MPa, the ultimate load-bearing capacity of the specimens increases by 19% and the ductility is improved. When the slenderness ratio increases from 5 to 12, the ultimate bearing capacity is subjected to 16.9% decrease. The ultimate bearing capacity concrete strength increases by 16.3% and 36.3%, respectively. Referring to the domestic codes and experimental results, calculation equations for the axial compression bearing capacity of medium-and-long steel tubular columns filled with high-strength self-stressing self-compacting concrete are proposed, which can provide reference for engineering design. © 2016, Editorial Office of China Civil Engineering Journal. All right reserved.