Use of thermoset- and thermoplastic-resin GFRP bars as internal flexural and shear reinforcement of concrete beams

Fiber-reinforced polymer (FRP) bars were proposed as an alternative to traditional steel bars to reinforce concrete members in particular conditions. Recently, newly developed thermoplastic-resin glass FRP (GFRP) bars have been proposed to obtain some advantages with respect to thermoset-resin GFRP bars. Thermoplastic-resin bars can be shaped on site saving shipping and manufacturing costs and can be recycled. However, studies regarding the use of thermoplastic-resin bars as internal reinforcement of concrete beams are still limited. In this paper, concrete beams reinforced with internal longitudinal and transverse steel, thermoset-resin GFRP, and thermoplastic-resin GFRP reinforcing bars are tested using a four-point bending test configuration. Beams were designed to attain shear failure. The experimental flexural behavior observed is studied with an analytical model based on cross-sectional analysis. Furthermore, models provided by available codes and guidelines are used to compute the GFRP-reinforced concrete beam resisting shear force, which is compared with that obtained experimentally. The results and discussion reported in this paper provide an insight into the bending and shear behavior of GFRP-reinforced concrete beams under service and ultimate conditions and show the effectiveness of both thermoset- and thermoplastic-resin GFRP bars as internal longitudinal and transverse reinforcement of concrete members.