Review of flexural behavior and design recommendations for ultra-high performance concrete members

This article presents a critical review of the flexural behavior and design recommendations for ultra-high performance concrete (UHPC) structural members. The fundamental characteristics of the flexural behavior of steel-reinforced UHPC beams and the similarities and differences between UHPC constitutive models used around the world are reviewed. The key factors (from a materials perspective) investigated in the literature, which influence the behavior of reinforced-UHPC flexural members, are fiber volume fraction, conventional steel reinforcement ratio, and material tensile behavior. Reinforcement fracture after crack localization, and insufficient accounting of the size effect and strain-hardening behavior of certain UHPCs are some of the outstanding challenges. The review presented in this article is expected to guide further development of the constitutive material models in flexural design recommendations, overcome existing challenges, and lead to better structural design, thus enabling more widespread use of UHPC in structural applications.