The interaction of steel tube and concrete core in concrete-filled steel tube columns

The load transfer by natural bond or by mechanical shear connectors and the interaction between the steel tube and the concrete core in concrete-filled steel tube columns are investigated experimentally and analytically. A total of 71 specimens are tested under axial compression loading applied to the steel tube alone, to the concrete core alone or to the steel tube and concrete core simultaneously at the top of the specimen, whereas the steel tube and concrete core are supported simultaneously at its bottom. The influence of a number of parameters is studied including the bond conditions, the cross section, the strength and type of concrete and the length of the specimen. For comparative study, nonlinear finite element models are developed using the general-purpose finite element software ABAQUS.