3D mesoscale modelling of steel fiber-reinforced aggregate concrete

Steel fiber-reinforced concrete (SFRC) is a versatile engineering material renowned for its exceptional strength, toughness, and durability. In order to gain a thorough understanding of the mechanical response and damage mechanism of SFRC, a novel 3D four-phase mesoscale model consisting of coarse aggregates, mortar, steel fibers (SFs), and interfacial transition zone (ITZ), is developed to investigate its compressive properties in this paper. We developed 3D random aggregate models that feature rough surface and sharp angular shapes to accurately mimic the coarse aggregates. Additionally, three types of SF models (straight, hooked-end and spiral) were established and randomly inserted into those aggregate models. Using a two-step meshing method and coupling technique, we established a high-efficiency finite element model to simulate the compressive behaviors of SFRC, including failure patterns, stress-strain curves, and cracking processes. Results indicated that the cracking in SFRC initiated from the micro-cracks in the ITZ phase, followed by the macro-cracks that propagate in the mortar matrix and were restrained or hindered by the surrounding SFs. Using our developed mesoscale model, the compressive strength, deformation properties of SFRC containing various types of SFs were investigated. The failure mechanism of SFRC was revealed through the simulation of crack-fiber behaviors at the meso‑scale. Based on the existing experimental findings, our proposed mesoscale model has been demonstrated to be highly reliable in analyzing the strength and damage patterns of SFRC, allow for further insights into the mechanical responses of different types of SFRC under various loading conditions.