Meso-mechanical modelling and analysis of the creep of steel-fibre-reinforced concrete

A three-dimensional meso-scale model based on the finite-element method was developed to simulate the creep response of steel-fibre-reinforced concrete (SFRC), which was treated as a composite of mortar, coarse aggregates and fibres. The SFRC meso-structures were randomly generated. The fibres were explicitly modelled using line elements, while the other two phases were modelled using solid elements. By attributing the creep response to the mortar phase while assuming the aggregates and fibres to be elastic, the proposed meso-scale model was able to simulate the compressive creep response of SFRC cylinders with different fibre contents. The model’s prediction of the compressive creep response was in good agreement with experimental studies in the literature. The model proposed was used to examine the effect of fibres on cracked SFRC specimens. Cracking was attributed to the mortar and the interfacial transition zone on the meso-scale, which were modelled using a continuum damage model and a cohesive zone model, respectively. Numerical simulations were carried out on notched SFRC beams subjected to sustained three-point bending to demonstrate the capability of the model in simulating the creep of cracked SFRC and capturing the crack-bridging effect of steel fibres.