Tensile Response of Reinforced Ultra-High-Performance Fiber-Reinforced Cementitious Composites: Modeling and Design Recommendations

The combination of ultra-high-performance fiber-reinforced cementitious composites (UHPFRCs) with reinforcing steel bars (R-UHPFRC) allows for structural solutions complying with severe durability and mechanical demands. However, models capable of describing the complete full tensile behavior of R-UHPFRC based on the mechanics of the involved phenomena and that can form the basis of design recommendations are still lacking. The purpose of this work is the development of a theoretical model for the uniaxial tensile response of R-UHPFRC, capable of describing both the pre-and post-yielding stage of the reinforcement. The tensile R-UHPFRC element is divided into a series of parallel crack elements with variable post-cracking strength. The solution of the bond problem resorts to the Tension Chord Model and accounts for the contribution of fibers at the cracks. Sensitivity studies are performed to assess the influence of the governing parameters. The calculated force-deformation responses and crack spacing are compared to existing experimental evidence. The model is then used as a basis for the proposal of design recommendations.