Fibre reinforcement technology has advanced significantly in recent years and, as a result, expanded into different applications. In particular, steel fibre-reinforced concrete has been successfully employed in flat slabs of several buildings in Europe with fibres as the only reinforcement. However, design methods for fibre-reinforced concrete (FRC) structures do not consider differences that may result from material characterisation tests that are not representative of the structural behaviour and fibre orientation of real-scale elements. In this regard, this paper presents a numerical study in which two constitutive models for FRC based on the bending test are applied to estimate the flexural behaviour of full-scale slabs of different dimensions. Likewise, a parametric study is conducted to analyse how the parameters of these constitutive models affect the flexural response of the slabs, and a numerical fit of the experimental data is performed. Finite element simulations using the constitutive models overestimate the experimental results. The parametric study also reveals that the parameter r2 (stress after cracking) has a particularly importance influence on the response. Furthermore, enhanced sectional behaviour of the slabs was observed as their width was increased.