EXPERIMENTAL STUDY OF EARTHQUAKE-DAMAGED RC FRAME COLUMNS STRENGTHENED WITH SPRAYED HYBRID BF-CFRP

An experimental investigation on the seismic behavior of earthquake-damaged RC frame columns strengthened with sprayed hybrid basalt and carbon fiber reinforced polymer ( BF-CFRP) was presented． Three specimens with 1 /2 scale were tested by horizontal cyclic loading combined with constant gravity loads． The test results indicated that after spraying repair the ultimate bearing capacity of the damaged frame column yielded steel bars was nearly restored to the level before its damage，the ductility coefficient and the cumulative energy dissipation were respectively increased by 7. 43% and 22%，and the stiffness degeneration rate beyond peak load was lower than that of unrepaired column; the peak load and the cumulative energy dissipation of the damaged frame column were respectively decreased by 11. 9% and 39% after spraying repair，the ductility coefficient was increased a little，and the initial stiffness was much lower than the other two specimens because of serious pre-damage，but the stiffness degeneration rate was almost the same as the other two due to the effective confinement action of sprayed FRP coatings． That is to say，the seismic behavior of earthquake-damaged frame column can be rehabilitated even enhanced through spraying hybrid BF － CFRP，which demonstrates that this method can quickly repair earthquakedamaged frame columns and effectively hinder the collapse of RC frame structures in aftershock．