Mechanic Model of Push-Out Test of Over-Thick CFST

Abstract

Analyze mechanical behavior of over-thick concrete filled steel tube ( over-thick CFST ) subjected to axial compression and revealed adhesive slip law of steel tube/concrete. 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 push-out test was carried out and axial displacements of concrete column and steel tube were measured. On the base of the test,the adhesive layer between the concrete and the steel tube is introduced and shearing stress-shearing strain curve is set up. The results show that the adhesive stress between steel tube and concrete is uniform along the height,and uniform slipping along the height exists.Therefore the adhesive stress between steel tube and concrete can be precisely measured by push-out test of over-Thick CFST subjected to axial compression. The following conclusions can be drown that axial symmetry elasticity modeling is correct for simulating push-out test of over-thick CFST. There is an adhesive thin player between steel tube and concrete, the slip can be equivalent to shearing deformation of the adhesive layer. The relation of shearing stress-shearing strain can be determined by the push-out test.