Axial compression behavior of CFRP reinforced concrete filled steel tubes with spherical-cap gap

In order to investigate the axial mechanical behavior of CFRP reinforced concrete filled steel tubes with spherical-cap gap, the axial compression tests of 8 specimens were carried out, including 2 concrete filled steel tubes with no gap, 2 concrete filled steel tubes with spherical-cap gap and 4 CFRP reinforced concrete filled steel tubes with spherical-cap gap. The effects of CFRP on the failure modes, load versus axial displacement curves, load versus axial strain curve, bearing capacity and ductility of the members were studied. The results show that the existence of gap will affect the mechanical properties of concrete filled steel tubular column. When the gap ratio is 6.6%, the peak load of the column decreases by 12% and displacement ductility coefficient decreases by 17%. CFRP improves the bearing capacity and deformation of the column. When strengthened by one-layer CFRP, the peak load and displacement ductility coefficient of the column increase by 9% and 7% respectively. When strengthened by two-layer CFRP, the peak load of the column increases by 26% and displacement ductility coefficient increases by 88%. © 2019, Editorial Office of Journal of Building Structures. All right reserved.