Abstract:

Seven concrete-filled steel tubular stub columns with different structures were investigated by an axialcompressive test in terms of the ultimate axial bearing capacity,the characteristics of the axial compressive failureand deformation,the ductility and the steel consumption.Experimental results indicate that ( 1) under axial compressiveloads,the restraint of the CFST column with binding bars on the core concrete is obviously improved,butthe corresponding distribution is uneven,thus limiting the increase of the overall strength and ductility of the concrete;( 2) as compared with the common square CFST column,the stiffened square CFST column uses less steeland achieves a more even restraint distribution,a better overall restraint effect,a greater axial bearing capacity,and a better ductility as well as less local buckling between the binding bars; and ( 3) the width-thickness ratio ofthe square CFST column greatly affects the corresponding axial compressive behavior; specifically,the bearing capacityductility coefficient of the CFST column as well as the longitudinal strain corresponding to the local bucklingincreases with the decrease of the width-thickness ratio.

Key words: concrete-filled steel tubular column, binding bar, stiffened belt, axial bearing capacity, ductility