Mechanical Properties of Octagonal Hollow Concrete Filled Steel Tube Short Columns Under Axial Compression

The mechanical properties of specimens, including the octagonal hollow concrete short columns with inner steel plate and the columns with inner longitudinal steel, were experimentally and numerically investigated under axial compression. The experimental phenomena, the whole test curves, the whole process of stress and the stress contact between each component were emphatically analyzed. The bearing capacity and the stiffness under axial compression obtained from tests were also compared with those calculated by using the revised Code for Design of Concrete Structures (GB 50010—2010). The results showed that the concrete, longitudinal bars and inner steel plates could work together under axial compression. The square high-strength hollow RC short columns showed high load-bearing capacity and stiffness. The sectional dimensions and concrete strength had significant influence on the bearing capacity, stiffness and ductility of the members. However, the thickness of inner steel plate had little influence. The predicted bearing capacity based on the revised GB 50010—2010 was conservative compared to the test results, while the prediction of the stiffness agreed well.