Flexural behavior of partially fiber-reinforced high-strength concrete beams reinforced with FRP bars

In this paper, the flexural behavior of partially fiber-reinforced high-strength concrete (FRHSC) beams reinforced with FRP bars was investigated. A total of 12 beams were tested under four-point bending. The effects of the thickness of FRHSC layer, steel fiber volume fraction and FRP reinforcement ratio were studied. The failure mode, flexural capacity, deflection, crack width and ductility of the tested beams were investigated. The results showed that adding steel fibers in tension zone is an effective way to overcome the large deflection and large crack width of FRP bar reinforced concrete beams and reduce the cost, however, the ductility of tested beams decreased with the addition of steel fiber into tension zone. The optimum thickness of FRHSC layer in FRP bar reinforced concrete beams was 0.57 times of the total depth of the beam. Higher FRP reinforcement ratio provided better flexural performance including higher flexural capacity, post-cracking stiffness and ductility and smaller crack width. A simplified calculation method for predicting the effective moment of inertia of fully and partially FRHSC beams reinforced with FRP bars was developed. The beam deflections calculated by the proposed method match well with the experimental results.