Mechanical performances of high-strength concrete-filled steel tubular medium-long columns with square cross section

In order to investigate the influence of concrete strength, slenderness ratio, and eccentricity on the ultimate bearing capacity, initial stiffness, and other mechanical properties of square high-strength steel tubular medium-long column, a total of 11 square column specimens were designed and made. The compression tests were carried out, and the load-longitudinal deformation curve, load-deflection curve, longitudinal strain distribution curve of mid-span section, and several failure modes of the composite column were obtained. Numerical simulations were conducted, and the results are in good agreement with the experimental results. It is found that the concrete strength has little effect on the initial stiffness of the square high-strength concrete-filled steel tubular medium-long column, and the ultimate bearing capacity and initial stiffness decrease with the increase of slenderness ratio and eccentricity, and the eccentricity has a particularly significant influence on the bearing capacity.