In the recent years, several studies have shown the effectiveness of using the externally applied fiber reinforced polymer (FRP) plates to reinforce cracked structures under cyclic loadings. Previous studies which used prestressed FRP plates have shown a substantial increase in the fatigue life of cracked beams and even, in some cases, a crack arrest. Nonetheless, no theoretical study on the sufficient prestressing level needed for a complete crack arrest exits. Hence, in this paper, a fracture mechanics based model is proposed to estimate the prestressing level needed to arrest the crack growth in notched steel beams. Several strengthened steel beams are tested under different fatigue loading ranges and the experimental results show the validity of the proposed fracture model.