Utilisation of simulation-driven fibre orientation for effective modelling of flexural strength and toughness in self-compacting concrete

The design of concrete elements reinforced with steel fibres should consider not only strength criteria but also residual tensile strength and post-peak behaviour, and the resulting improvement in toughness. This paper introduces an innovative finite element modelling approach to simulate the flexural properties and post-cracking performance of self-compacting concrete (SCC) reinforced with steel fibres, considering varying fibre orientations and distributions. The concrete matrix was modelled in ABAQUS using the damage plasticity model, with automated fibre distribution and orientation, evaluating SCC flow-based, random, and longitudinal span alignment of the fibres. Numerical simulations of plain and reinforced SCC were validated using three-point bending tests on notched prism specimens in accordance with ASTM C1609. Further simulations assessed the impact of fibre orientation on the flexural strength and toughness of reinforced concrete, comparing random and longitudinal fibre alignments. The simulation results for plain SCC and fibre-reinforced SCC with fibre orientation based on the flow of SCC closely matched the average experimental curve, demonstrating a high degree of accuracy. Furthermore, the results indicated that longitudinal alignment of fibres can enhance flexural strength and toughness by up to 104.4 % and 127.1 %, respectively, compared to a random fibre orientation in fibre-reinforced SCC.