Mode-Ι fracture of steel fiber reinforced concrete at low temperatures: Characterization with 3D meso-scale modelling

Abstract

To investigate the mode Ι fracture behavior of SFRC (Steel Fiber Reinforced Concrete) at low temperatures, 3D meso-scale models of SFRC specimens with different steel fiber volume fractions (Vf = 0.0 %, 0.5 %, 1.0 % and 1.5 %) were developed by means of finite element analysis. The corresponding failure patterns as well as fracture properties were obtained by three-point bending simulations at low temperatures. SFRC is regarded as a multiphase material composed of mortar, aggregate, ITZ (Interface Transition Zone) and steel fiber at the mesoscopic scale. The comparison between simulation results and the test results verifies that the meso-scale numerical model could well describe the mechanical behavior of SFRC. The simulation results show that the fracture energy and unstable fracture toughness of SFRC significantly increase with the increase of fiber volume fraction and the decrease of temperature. The characteristic length of SFRC decreases with decreasing temperature but increases with increasing fiber volume fraction. The initial fracture toughness is less affected by fiber content while increasing with decreasing temperature. The prediction formulas were proposed which could be used to predict the fracture energy, characteristic length and unstable fracture toughness of SFRC at low temperature, respectively.