Axial compressive performance of concrete-filled double skin steel tubular columns using recycled aggregate concrete

This study aims to investigate the axial compressive performance of concrete-filled double skin steel tubular (CFDST) columns utilizing recycled aggregate concrete (RAC) through experimental and numerical methods. Fourteen column specimens were tested under axial compression to analyze their failure modes, load and strain responses. A finite element model was developed and validated, enabling a parametric study to examine the influence of key factors. Furthermore, the calculation method for predicting the axial compression resistance of CFDST columns specified in current Chinese standard, initially proposed for normal concrete members, was assessed for its applicability for the RAC counterparts. The findings showed that the CFDST columns using RAC achieved effective confinement effect between the steel tubes and sandwiched RAC, exhibiting ductile behaviour under axial compression. The assessment revealed that the current calculation method provided reasonably accurate predictions for the axial compression resistance of CFDST columns filled with RAC.