In order to further understand the impact behavior of reinforced concrete beams strengthend with externally bonded FRP sheet, one RC beam without stirrups and two FRP strengthened RC beams without stirrups were tested against impact loads and one FRP strengthened beam was tested under static load. Test results showed that the impact resistance of FRP strengthened RC beams significantly increased, especially when the beams was strengthened with end anchorage. The failure modes and time-histories of impact force, mid-span displacement, strain of longitudinal reinforcement were analyzed and discussed, the shear mechanism of CFRP strengthened RC beams without stirrups under impact loading was obtained. The failure process can be divided into two stages, the shear failure of local part of the beams adjacent to the mid-span section under impact loading and the subsequent shear failure of near-support section under reaction force. The FRP contribution to shear strength at the two stages was discussed respectively and compared with the predicted shear strength according to different design codes. The comparisons showed that, FRP contribution to shear strength under impact loading at both stages was higher than predicted shear strength. Compared with the previous method to predict the bond strength of CFRP-to-concrete interface under impact loading, it could offer reliable reference to reasonably evaluate the contribution of FRP to shear strength.
Key words
RC beams without stirrups /
CFRP strengthened /
impact behavior /
shear mechanism
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