Experimental Research on Seismic Behavior of Seismically Damaged RC Frame Column Strengthened with Sprayed Hybrid BF/CFRP

This experimental program was designed for investigating the seismic behaviors and strengthening effect of pre-damaged RC frame columns retrofitted with sprayed BFRP and hybrid BF/CFRP. Four RC frame column specimens, among which one was unstrengthened and three was pre-damaged and strengthened with sprayed FRP, were tested under an incremental loading procedure of the pseudo-static, cyclic shear loads combined with constant gravity loads. The test results including the failure mode, ultimate bearing load capacity, load-displacement hysteresis curves and ductility of specimens were obtained and analyzed. It indicates that spraying hybrid BF/CFRP strengthening scheme can effectively improve the ductility and energy dissipation ability of pre-damaged concrete frame columns. Although the improvement of the peak loads and ultimate lateral deformation of damaged frame columns were not obvious compared with those of the reference column, but it should be pointed out that the strengthened columns were pre-damaged seriously with yielded steel bars and the recover of load bearing ability resulted from spraying FRP retrofit can not be neglected. It also shows that increasing the thickness of spraying overcoat can effectively improve the energy dissipation ability of damaged frame columns.