Analysis of Mechanical Behavior of Push-Out of Over-Thick Concrete Filled Steel Tube

Axial symmetry elasticity modeling of the concrete column which is constrained by over-thick steel tube and pushed out under axial compressive load is set up. The basic displacement method equations are derived. The distributions of displacement, stresses and strains of the concrete column are given. The experiment of push-out of over-thick concrete-filled steel tube (Over-Thick CFST) was carried out. The curve of axial load-vertical displacement at the upper surface is measured. On the base of the test, the adhesive thin-layer between the concrete and the steel tube is introduced. The thickness of the adhesive thin-layer is approximated measured. The experimental results show that the shearing stress in the adhesive thin-layer is uniform along the height, which is coincide with the results obtained by the axial symmetry elasticity modeling of the concrete column which is constrained by over-thick steel tube and pushed out under axial compressive load. Therefore, the adhesive shearing stress between steel tube and concrete can be precisely measured by the experiment of push-out of Over-Thick CFST. The relation of shearing stress-shearing strain of the adhesive thin-layer can be determined.