Abstract:In order to study the effects of concrete strength, diameter-to-thickness ratio, CFRP (carbon fiber reinforced composite) layer number and CFRP cladding mode on the axial compression behavior of CFRP confined concrete-filled circular steel tube, the axial compression comparison tests of 6 concrete-filled circular steel tube short columns and 18 CFRP-concrete-filled steel tube short columns were carried out. It is found that the CFRP constraint significantly increases the bearing capacity of concrete-filled circular steel tubes, and the increasing range of the bearing capacity increases with the increase of CFRP layers. The failure pattern of high strength and ultra-high strength concrete-filled steel tube short column is shear failure with poor ductility. CFRP constraint can improve its ductility, and more CFRP layers result in better ductility. The performance of half-packaged CFRP specimens is close to that of full-packaged CFRP specimens. CFRP binding effect decreases with the increasing diameter - thickness ratio. If the bond is good, CFRP and steel tube can work together before the specimen fails. Finally, three classical formulas of axial bearing capacity of CFRP confined CFST are selected for calculation, and the formula based on the double restraint formula of CFRP and steel tube can better predict its bearing capacity.