Experimental study on the shear behavior of GFRP reinforced concrete beams strengthened using CFRP sheets

Abstract

This paper presents the results of an experimental investigation on the shear capacity of reinforced concrete beams. The beams under consideration are reinforced with glass fiber-reinforced polymer (GFRP) bars. Also, the effect of shear strengthening on such beams is studied. For this purpose a total of four beams were tested where two served as control beams, while the other two were strengthened using U shape carbon fiber-reinforced polymer (CFRP) sheets, bonded externally. Each beam is 2.4 m long, simply supported and subjected to a four-point load under displacement control mode. The strengthened beams showed a noticeable increase in the load-bearing capacity of the specimen. The failure load recorded of these specimens was 208 kN, an increase of 25%. Moreover, the mode of failure changed from pure shear to concrete crushing in the compression zone. The results indicate that using CFRP sheets to strengthen GFRP reinforced beams in shear is a viable option. However, the results also suggest that the known adverse interaction between EB-CFRP and conventional steel stirrups could be applicable between EB-CFRP and GFRP shear reinforcement in strengthened beams. Therefore the predicted EB-CFRP shear capacity by ACI 440.2R turned to be unconservative when compared to the experimental results.