An analytical method for three-point bending notched beam strengthened with CFRP sheet

ABSTRACT

The present study presents an analytical method to predict the fracture behaviors of CFRP (carbon fiber-reinforced polymer) sheet strengthened three-point bending notched beam. Both the vertical crack propagation in the concrete and interfacial debonding at the CFRP-concrete interface are considered. Fictitious crack model and compatibility conditions are utilized in the analytical study. Interfacial debonding is considered as interfacial shear crack. Four different stages generally occur during the process of loading. In the first stage, only ficti-tious crack propagation appears in the concrete without interfacial debonding. In the second stage, both the fictitious crack propagation and interfacial shear crack propagation are consid-ered. In the third stage, macro-crack appears in the concrete due to the increasing of the crack width. Finally, macro interfacial crack appears at the CFRP-concrete interface and the strength-ened beam fails. Moreover, due to the fully propagations of the fictitious crack in the concrete and the interfacial shear crack at the interface, the applied load would attain two peak values during the loading process. If the ratio of the CFRP rigidity to the beam rigidity is very low, there is only one peak value due to the insignificant effects of the CFRP sheet.