Axial compressive performance of unsymmetrical steel-reinforced concrete stub columns

The axial compression capacity of steel reinforced concrete (SRC) stub columns with unsymmetrical steel sections (USSs) was investigated in this study. Axial compression tests were conducted on four SRC stub columns with USSs, and internal force analyses were conducted on a total of 22 finite-element models. The failure modes, load–displacement curves and internal forces were used to analyse the mechanical behaviour and bearing capacity of the columns under axial compression. Furthermore, the variables that influence the axial compression capacity comprising different width-to-thickness ratios of the steel flange, area ratio of the steel section to the confined concrete, web eccentricities and steel eccentricities were investigated in a parametric analysis. The results showed that, compared to SRC stub columns with symmetrical steel sections (SSSs), the columns with USSs showed slightly flexural failure. Steel eccentricity was the main factor that affected the axial compression capacity of SRC stub columns with USSs. An equation was proposed for calculating axial compression capacity of an SRC stub column with a USS considering steel eccentricity. Results calculated by the proposed formula showed better agreement with the experimental value than that calculated by the codes, and the formula is also applicable to SRC stub columns with SSSs.