Study of recycled concrete-filled steel tubular columns on the compressive capacity and fire resistance

Abstract

This study presents the analytical formulation of circular steel tubular column with hollow concrete section. This unified analytical formulation can evaluate the axial compression capacity and buckling load of this innovative composite section at normal and high temperature levels, as well as the normal and recycled concrete in a similar fashion. Therefore, the confinement effect on this composite section is uncertain, which in turn leads to complications in axially loaded compression evaluation, because the inner surface of the hollow concrete section is unrestrained. To this end, this study adopts the effective constraint, which can further assist in transmitting from normal concrete to recycled concrete material to address sustainability issues. In addition, the concept of average temperature is proposed to formulate the failure load of circular hollow recycled concrete-filled steel tubular section and circular hollow concrete-filled steel tubular section columns at high temperature.