Behavior of concrete-filled SHS steel tubes under different loading conditions

The experimental research has been made to study the behavior of specimens under different loading conditions, which include the steel tube and core concrete to be simultaneously loaded, only the core concrete to be loaded, only the core concrete to be loaded together with grease between steel tube and core concrete. At the same time, the finite element method is used to analyze the behavior of concrete-filled square hollow-section (SHS) steel tube under different loading conditions. The accuracy of the proposed method is assessed by comparing the analytical values with corresponding experimental ones. For the three loading conditions, the results show that the difference on bearing capacity will become larger with the increase of steel ratio. For the single concrete core specimen with lower steel ratio, the bearing capacity is the lowest, but its ductility is the best. With the increase of steel yield strength, the bearing capacity will increase evidently for the specimen loaded simultaneously. While for the specimen with core concrete, the steel yield strength has little influence except increase of the ductility.