Experimental study of RC jacketed and CFRP strengthened RC beams

• RC jacketing and CFRP strengthening are studied as two retrofit techniques.
• Overall behavior, failure modes, and crack propagation are studied extensively.
• Strength, ductility, and energy dissipation capacity are discussed and compared.
• Conventional analytical methods are proved to predict ultimate moment accurately.

This paper presents the results of an experimental study on retrofitting RC beams using FRP strengthening and RC jacketing. Three-point loadings are applied to twelve strengthened beams and three reference specimens to put the two techniques into perspective. Formation of first cracks, FRP debonding, and onset of concrete crushing are compared and discussed. Load–deflection behavior, failure modes, and crack propagation patterns are studied extensively. The experiments demonstrate that the RC jacketed beams exhibit a flexural failure identical to the reference beams. However, the FRP strengthened beams fail in a relatively small deflection due to the premature FRP debonding. Furthermore, the both techniques noticeably enhance strength and energy dissipation capacity. The applied RC jacketing can also improve ductility; however, the FRP method cannot provide sufficient ductility. Therefore, the RC jacketing can be used in seismic zones as an alternative to the FRP method. In addition, conventional analytical methods are applied for evaluation of ultimate moment, and the results are compared with the experiments. Good agreement between the results verifies the analyses.