Flexural behavior of concrete beams externally strengthened with CFRP sheets

This paper presents the flexural performance of reinforced concrete (RC) rectangular beams strengthened with carbon fiber reinforced polymer (CFRP) sheets which were subjected to four-point bending to investigate the effect of fiber reinforcement on the pre-cracked beams strengthened. The main experimental parameters included in the study are the pre cracked width, the longitudinal tensile reinforcement ratio, the shear span ratio, and the concrete cover thickness. In total, five beams were cast, one beam without any reinforcement as a control beam, and four pre-cracked beams repaired with two layers of CFRP sheets. Test results show the effectiveness and flexural capacity of the CFRP strengthened beams. The flexure enhancement of the CFRP strengthened beams varied between 34% and 124% over the control beam. This study confirms that the CFRP reinforcing technique applied in this paper could significantly enhance the flexural capacity of RC beams. Finally, the theoretical and practical formula for calculating the crack and ultimate strength of RC beams strengthened with CFRP sheets was established. The results showed that the theoretical calculation is in accord with the experimental data.