Static behavior of reinforced UHPFRC beams with minimal cover thickness

Because of its high tensile strength and deformation capacity, UHPFRC (Ultra High Performance Fiber Reinforced Cementitious composite) can theoretically be used without any reinforcement bars or prestressing. However, for more economical design and for reasons of structural robustness, steel rebars should complement the UHPFRC leading to R-UHPFRC (Reinforced UHPFRC) structural elements. This paper focuses on the quasi-static behavior of UHPFRC beams reinforced with single steel rebar. The beams are full-scale elements (2 meters or 6.6 feet span, 0.4 meter of 1.3 feet height) inspired by a recently built R-UHPFRC railway bridge in Switzerland. They were prefabricated using one-way casting and external vibrations, to provide similar conditions as in mass production. The members are tested under quasi-static loading in four-point bending. Reinforcement cover thickness is only half of the bar diameter. Two bar diameters are tested (20mm/0.79in and 34mm/1.34in). The material properties variation within the member and the cover performance are discussed.