A generalised predictive model for the mechanical properties of mono/hybrid fibre-reinforced ultra-high-performance concrete

Steel fibre, which can exist in the form of mono (single) or hybrid method, exhibits a distinctive fibre reinforcing effect in ultra-high-performance concrete (UHPC). Motivated by the intricate interplay of fibre effects and the ambiguous findings reported in past literature, as well as their limited comparability, the primary objective of this study is to systematically and comprehensively investigate the individual influences of fibre length, fibre geometry, fibre content, hybrid combination type, and hybridisation ratio on the flowability, compressive, and flexural performance of mono and hybrid fibre-reinforced UHPC. In addition, recognising the limited models available to predict the properties of hybrid fibre-reinforced UHPC, we developed two novel non-linear models capable of accurately predicting the compressive and flexural strength of both mono and hybrid fibre-reinforced UHPC together. These models were derived by integrating data from an extensive database encompassing both experimental and literature data. The comprehensive evaluation of the proposed models revealed their excellent accuracy in predicting the mechanical performance of both mono and hybrid fibre-reinforced UHPC.