Three-dimensional meso-scale modelling of failure of steel fiber reinforced concrete at room and elevated temperatures

Steel fiber reinforced concrete (SFRC) is composed of coarse aggregate particles, mortar matrix, fibers, pores and microcracks from the viewpoint of meso-scale. To reflect the mesoscopic characteristics more realistically, a three-dimensional meso-scale model for SFRC was established. In the model, the fibers were explicitly modelled while the concrete matrix was regarded as a tri-phase composite consisting of aggregate, mortar matrix and the interface transition zones (ITZs) between them. Based on the idea of classical random aggregate model for plain concrete, a programme was designed to randomly distribute aggregate particles and steel fibers. The meso-scale numerical model was verified by the good agreement between simulation results and the available test results. The dynamic failure behavior of SFRC at room and elevated temperatures was investigated by utilizing the simulation method. The simulation results indicate that for fiber content no larger than 2% volume, the influence of steel fiber on thermal conduction of SFRC can be ignored. Compared with that of plain concrete, strain rate effect on compressive strength of SFRC is weaker and it would be further decreased under high temperatures. The improvement of SFRC performance induced by steel fiber increases for higher fiber volume fraction whilst decreases with respect to strain rates, regardless of temperature. When the fiber amount is identical, the dynamic compressive strength of SFRC decreases slightly in the case of larger fiber diameter or smaller fiber length. (C) 2021 Elsevier Ltd. All rights reserved.