Axial compression mechanical properties of UHTCC-hollow steel tube square composited short columns

To investigate the mechanical properties of ultrahigh toughness cementitious composite (UHTCC)-hollow steel tube square composite short columns under axial compression, axial compression tests were conducted on 10 composite short columns organized into five distinct groups. Parameters such as the size effect and hollow ratio were used to test the variation of ultimate load and ultimate strength. The interface microstructure was characterized through scanning electron microscopy and X-ray powder diffraction analyses. Variations in ductility, strength, and energy dissipation coefficients were assessed with respect to the selected parameters. A stress-strain constitutive model for the composite short columns was formulated. Furthermore, a finite element model was constructed using the ABAQUS software suite, and the simulation results were subsequently compared against the experimental findings. A design method for the ultimate load-carrying capacity of composite short columns was also developed. Experimental outcomes, coupled with microstructural analysis, indicated that under axial compression, the components exhibited effective collaborative deformation capacity. The loadbearing capacity of composite short columns increases with their increasing size, whereas their strength decreases with increasing size. The size effect exhibited a substantial impact on the strength, energy dissipation, and ductility coefficients, whereas the hollow ratio had a comparatively minor effect. The constitutive model demonstrated strong alignment with the experimental values. The effective constraint coefficient was derived by dividing the effective controlling area, which led to a calculation formula for determining the ultimate loadcarrying capacity of a composite short column under axial compression. The experimental, simulated, and theoretical values exhibited a high degree of consistency.