Study on axial static buckling performance of square cross-section aluminum foam-filled steel tubes

To study the axial static buckling performance of square cross-section aluminum foam-filled galvanized steel tubes, 40 specimens were tested in four groups. The axial buckling loads and buckling modes of aluminum foam-filled galvanized steel tubes were investigated. The effects of parameters such as aluminum foam density, length-to-width ratio, and steel tube thickness on the average and maximum buckling loads and buckling modes of aluminum foam-filled galvanized steel tubes were explored. The test results showed that the addition of aluminum foam increased the stiffness of the outer galvanized steel tube, changing the buckling mode from symmetric to asymmetric, with a noticeable increase in the number of buckling wrinkles. The average and maximum buckling loads increased with the increase in the relative density of the aluminum foam and the thickness of the outer steel tube. The maximum crushing loads of galvanized steel tubes with thicknesses of 1.5 mm and 2 mm are 1.7 and 3.6 times that of a galvanized steel tube with a thickness of 1 mm, respectively. In contrast, the maximum crushing loads of foam aluminum-filled galvanized steel tubes with thicknesses of 1.5 mm and 2 mm are 2.3 and 3.7 times that of a foam aluminum-filled galvanized steel tube with a thickness of 1 mm, respectively. After the galvanized steel tube is filled with aluminum foam, the foam filler can significantly enhance the bearing capacity and stiffness of the structure, and improve the impact resistance of the structure. Considering the interaction effect between the outer steel tube and the filled aluminum foam, theoretical analyses were conducted on the average and maximum buckling loads of aluminum foam-filled steel tubes, and the theoretical calculation results matched well with the experimental results.