Modelling the influence of the fibre structure on the structural behaviour of flowable fibre-reinforced concrete

•A modelling approach is devised that takes into account the fibre structure of FRC.•The approach makes use of a single-phase material definition.•It was validated by studying the mechanical behaviour of two flowable FRC beams.•It could explain the large impact of the fibre structure experimentally observed.

This paper presents a modelling approach for fibre-reinforced concrete elements in which the fibre structure is taken into account in simulating the mechanical behaviour. The fibre structure is discretized in volumes and two fibre parameters are defined for each discrete volume: the dominant fibre orientation and the fibre volume fraction. These parameters are incorporated in a numerical model that uses a single-phase material definition dependent on the fibre parameters. The first part of this paper describes the methodology and constitutive modelling. The second part addresses the simulation of two beams that exhibited large differences in bending because of uneven fibre distribution. Data on the fibre structure was obtained using Computed Tomography scanning. The modelling approach captured the large difference in the flexural response of the two beams and provided an adequate prediction of the location and propagation of the critical cracks.