Experimental and Analytical Study of Fatigue Behaviour of Reinforced UHPC Beams

: The main objective of the research project reported in this paper is to develop a new type of high performance light beam that will increase the performance of usual beams (timber steel or RC beams) by combining FRP rebars cast in a ultra-high-performance concrete with short fibre reinforcement (UHPC-SFR). The beam is obtained to get a light beam with a high compressive and tensile capacity to sustain high bending moment and to be also shear resistant. The hybrid beam thus obtained possesses a lower bending stiffness than a glulam beam or steel beam of similar overall dimensions but a higher ultimate load capacity. One model is developed to validate this concept is presented in this paper. It is an analytical model based on the usual force equilibrium hypotheses. The load-displacement and moment-curvature relationships are compared to experimental results obtained from 5 large scales specimens. The results show good correlation between analytical and experimental results, and illustrate the potential interest of such composite beam configurations for civil engineering structures. Fatigue behaviour is also investigate UHPC and on 6 large scale beams.