Theoretical model for CFRP-confined spontaneous combustion gangue coarse aggregate concrete-filled steel tube stub columns under axial compression

To investigate the axial compressive behavior of carbon fiber reinforced polymer (CFRP)-confined spontaneous combustion gangue coarse aggregate (SCGCA) concrete-filled steel tube (CFST) stub columns, 18 CFRP-confined SCGCA CFST specimens and 9 SCGCA concrete specimens were tested with the parameters of SCGCA replacement ratio and CFRP jacket stiffness. The results revealed that the dual confinement provided by CFRP jackets and steel tubes significantly enhanced the strength and ductility of SCGCA concrete, while their confinement effectiveness reduced with the increase of the replacement ratio. Furthermore, an existing theoretical model for CFRP-confined natural coarse aggregate (NCA) CFST was modified to apply for CFRP-confined SCGCA CFST.