Improper execution of bonding of FRP plates to the RC beam can result into appearance of zones where the bond is substantially weaker, and air pockets are present. This paper presents an attempt to model the weak bond zone and its influence on the global response of the externally CFRP strengthened RC beam. A numerical displacement-based fibber model was used for the prediction of the response of RC beams externally strengthened with CFRP. Also, using the concepts of artificial neural networks and the results of the performed numerical analyses, another prediction model has been made. Both models generated excellent results and some of them will be presented further below in this paper.