CFRP strengthening reinforced concrete arches: Strengthening methods and experimental studies

To improve the strength, stiffness and ductility of reinforced concrete (RC) arches, carbon fiber reinforced polymers (CFRPs) were applied through bonding and bonding/wrapping techniques. Experiments were designed and carried out to reveal the strengthening effects of different CFRP strengthening schemes. It is found that bonding/wrapping technique is much more effective than bonding method. Strengthening effect of CFRP to the semi-circular arch whose rise-to-span ratio is 0.5 is much smaller than in arches with smaller rise-to-span ratio. A structural model was proposed to reveal the distribution of the interfacial stresses. It is found that the normal peeling stress and the shear stress jointly control the debonding of the CFRP at the vault while the interfacial shear stress is dominant at the feet. Based on the critical tensile strain of the concrete, a quantitative model was proposed to predict the debonding load of the strengthened arch. It indicates that the formation of the tensile crack in the concrete induces the debonding of the CFRP plates for the semi-circular RC arch at the vault. Five-hinge plastic model and a shear model were proposed to predict the failure of the strengthened RC arches.