Flexural behavior of RC beams externally reinforced with carbon fiber sheets

This paper presents the results of an experimental program on the behavior of RC beams strengthened using continuous carbon fiber reinforced plastic (CFRP) sheets. Externally reinforced concrete beams with epoxy-bonded CFRP sheets were tested to failure using a symmetrical two-point concentrated static loading system. Ten specimens were cast for this test program. One of them was a control beam without CFRP sheets, three of them were reinforced with only CFRP sheets on the tension surfaces of the RC beams to enhance their flexural strength, three of them were reinforced with a soft adhesive layer and CFRP sheets, and the remaining three were reinforced with a soft layer and CFRP sheets plus 5-cm-wide strips of CFRP sheet wrapped around the web. Experimental data on strength, stiffness, strain of tension steel rebar and CFRP sheet, deflection, and failure mode of each of the beams were obtained. The results generally indicated that (1) the flexural strength of the strengthened RC beams increased; (2) the ductile behavior of the beam reinforced with strips of CFRP sheet was significant; (3) the failure mode was a breakage of the CFRP sheet by the joint use of a soft adhesive layer; and (4) the maximum load was determined by the CFRP sheet breakage.