Nowadays, fracture mechanics modeling for strengthening structural members is a challenging issue for structural engineers. The developed fracture mechanics modeling was applicable for identifying propagation of a crack in concrete structural members such as beam-column connections. In the present paper, a numerical model derived from nonlinear fracture mechanics is developed to simulate the propagation of a crack in Carbon Fiber Reinforced Polymers (CFRP)-strengthened the connection. To validate the proposed model, two beam-column connections were made and tested. By using the proposed model, the outputs of the CFRP-strengthened connections show good agreement with the experimental results (8–12 %). It was also observed that propagation of the crack in the beam was prevented by the CFRP sheets. The average decrease was 36.9 % of the crack length compared with the control connection. The findings revealed that cracks formed in the connection area in the control specimen while extensive cracks appeared in the beam in the specimen strengthened by CFRP sheets.