Experimental study on the steel-concrete bond behaviour of circular concrete-filled stainless steel tubes

The paper reports an experimental investigation on the bond stress-slip relationship in concrete-filled stainless steel tube (CFSST) structures. Push-out tests were conducted on twelve specimens covering two stainless steel grades, two concrete grades, two cross-sectional dimensions and two internal ring conditions (with and without the internal ring). The effects of these factors on the bond stress-slip relationship in CFSST members were analysed and discussed. A theoretical model, based on the assumption that no restraining force from the steel tube was applied to the concrete core, was developed to predict the bond stress-slip response of CFSSTs and was evaluated against the test results. An empirical model was also proposed based on regression analysis to replicate the experimental bond stress-slip relationships, which can be used as input data for analytical and numerical simulations in future studies of CFSST structures.