Modeling of Ultra-High-Performance Fiber-Reinforced Concrete in Shear

Ultra-high-performance fiber-reinforced concrete (UHPFRC) is a material attracting increased use to solve practical engineering problems. Although significant research has been undertaken to develop constitutive models for finite element modeling of steel fiber-reinforced concrete (SFRC), the reliability of these models in characterizing UHPFRC remains unassessed. Specifically, only limited research is available on rational models for describing post cracking tension and shear-related mechanisms in UHPFRC under various loading conditions. To address these modeling deficiencies, this study investigates existing SFRC material models for their suitability in finite element analysis of UHPFRC. Localized behavior at cracks is investigated, leading to improvements in crack-related formulations through the inclusion of effective aggregate size. An embedded steel reinforcement rupture formulation for elements subjected to tension is also implemented to better capture rupture strains in specimens containing conventional reinforcement. Validation studies are provided to demonstrate the effectiveness of the proposed model improvements.