Influencing factor analysis on failure modes of concrete-filled steel tubular stub columns subjected to axial compression

Based on the experimental researches and theoretical analysis, the factors including cross-section shapes of the steel tubes, strength of the core concrete, diameter thickness ratios of the steel tubes, loading conditions and adhesive strength are carried out to discuss their influence on the failure modes and basic behavior of concrete-filled steel tubular (CFST) stub columns. It is found that the influence can be represented by the confining effect between the steel tube and the core concrete. Namely the CFST stub columns are prone to have 'drum shape' failure mode with the confining effect being strong, while shear failure mode may happen with a weak confining effect. Due to the characteristic of high-strength concrete, the mechanical behavior of the CFST stub columns has not a linear relationship with the strength of the core concrete.