Experimental study and numerical analysis of the interfacial bonding performance of T-shaped concrete-filled steel tubes

The effects of core concrete strength (C30, C40, and C50), steel tube length (600, 1000, and 1400 mm), and steel tube wall thickness (3, 4, and 5 mm) on the bonding performance of T-shaped concrete-filled steel tubes (CFSTs) were systematically investigated using push-out test. Via the test, the patterns of the failure modes, load-slip curves, stress-slip curves, and distribution law of longitudinal strain were observed for the specimens, and the bond-slip constitutive model for T-shaped CFSTs was established. The test results indicate that the bond stress of T-shaped CFSTs increases with the increase in concrete strength and tube wall thickness, while the steel tube length has less influence on the bond stress. In addition, non-linear spring elements were used to simulate the interfacial bonding behavior based on the bond-slip equation, which is in good agreement with the experimental curve results.