Mechanical behaviour of ultra-high-performance short-fibre-reinforced concrete beams with internal fibre reinforced polymer bars

Abstract The primary objective of this research was to develop a new type of high-performance lightweight beam providing better performance than conventional beams made of timber, steel or reinforced concrete (RC) by casting fibre-reinforced polymer (FRP) reinforcing bars (rebars) in ultra-high-performance concrete with short fibre reinforcement (UHPC–SFR). This new type of beam was developed to be lightweight, have high compressive and tensile strength, be able to sustain large bending moments and be resistant to shear. The main objective was to verify the mechanical behaviour of the beams and compare it with typical RC beam behaviour. For this purpose, an experimental program was designed to identify the failure modes and bending behaviour. The results indicate that the behaviour of such RC beams can be compared to typical RC beam behaviour to a certain extent. A model to validate this concept is presented in this paper; this analytical model is based on typical material law behaviour hypotheses of beam nonlinear mechanical behaviour. The load–displacement and moment–curvature relationships predicted with this model were compared to the experimental results obtained for four large-scale specimens. The comparisons revealed good correlation between the analytical and experimental results and illustrate the potential of these composite beam configurations in civil engineering structures.