Experimental and Analytical Investigation of Deflection of R-UHPFRC Beams Subjected to Loading-Unloading

Under service conditions, R-UHPFRC (Reinforced Ultra High Performance Fiber Reinforced Cementitious composite) beams exhibit residual deflection after loading-unloading. This is due to the tensile strain hardening behavior of UHPFRC. The precise calculation of deflection is thus relevant and was not addressed previously. This paper proposes a material model for UHPFRC under loading-unloading and a numerical layered model for the calculation of stress and strain distribution in the cross section. Then, a curvature-based analytical model is presented for calculation of deflection of a beam. This method is finally compared and validated against experimental results as obtained from four-point bending of full-scale R-UHPFRC beams. This research reveals the need for a specific material model for UHPFRC subjected to loading-unloading for the precise calculation of the structural response of elements and members under repetitive loading, such as service or fatigue loading.