Compression tests on square, thin-walled steel tube/bamboo-plywood composite hollow columns

Thin-walled steel tube/bamboo-plywood composite hollow columns (SBCCs) have excellent physical and mechanical properties. The simple cross section of this composite makes it simple to process and suitable for industrial production. In this paper, axial and eccentric compression tests were conducted on 21 specimens to study the failure characteristics and maximum bearing capacity of this composite. The test results showed that compressive failure in an SBCC is primarily characterized by damage from glue failure at the matrix interface at the end of the column, internal damage of the bamboo-plywood material, damage from glue failure on the tension side in the middle of the column, and buckling damage to the plywood material on the compressive side. The overall adhesive strength between the matrixes primarily determined the failure mode. The maximum bearing capacity of the SBCC generally increased with the net cross-sectional area of the bamboo and decreased with the slenderness ratio and eccentricity. The hollow ratio reduced the slenderness ratio of the test specimens with the same net cross-sectional area of the bamboo and increased the critical compressive load, which significantly improved the compressive load capacity, as was reflected in the slenderness ratio. Finally, a model was formulated based on a non-linear regression analysis of the experimental data. The model was used to determine the allowable compressive capacity of an SBCC to provide guidance for engineering applications.