EXPERIMENTAL INVESTIGATION ON THE INTERFACIAL DEBONDING BETWEEN CFRP AND POST-FIRE CONCRETE UNDER RAPID LOADING

Seventy-two single shear tests of post-fire concrete specimen externally bonded by CFRP sheet were carried out under the condition of rapid loading. The interfacial strain distribution is fitted by using the Dai model, the effect of concrete strength, loading rate and heating temperature on the interfacial shear strength, shear stress, fracture energy and bond-slip relationship are discussed respectively. Results show that the interfacial shear strength, the maximum shear stress and the interfacial fracture energy increase along with the upgrade of the concrete strength and loading rate, but decrease with the rise of the heating temperature, especially over 500℃. Typically, the interfacial fracture energy of the specimen with the heating temperature of 700℃ decreases by 83.8%, compared with the specimen with normal temperature, and the average peak shear stress decreases by 33.0%. The effective bonding length decreases slightly with the increase of concrete strength and strain rate but increases significantly with the increase of heating temperature. The effective bonding length of the specimens under normal temperature is between 70 and 90 mm, but the value reaches 165 mm for the specimen with the heating temperature of 700℃.