Behavior of Box Concrete-Filled Steel Tube Columns Considering Confinement Effect

In recent years considerable attention has been given to estimating the strength of box concrete-filled steel tube (CFST) stub columns. The effect of confining pressures is one of the complexities in determining the ultimate strength of the CFST columns. An experimental database of 188 tested columns has been used to produce two types of formulae: modified and simplified, that can help to predict the ultimate strength of box CFST columns with a wide range of geometrical and material properties. Different code procedures and previous formulae given by other authors were used for verification purposes and to show reliability. The axial load-shortening behaviors of composite columns were plotted using a proposed model of confined concrete adopted in a finite element analysis and compared with the experimental results. It has been found that the present formulae and concrete model have given results that agree quite well with the results of the experimental tests.