This paper provides a series of simple equations that allow the structural engineer to predict the mechanical properties across the section of roller bent wide flange steel members: proportional limit, yield stress, ultimate tensile stress, strain at ultimate tensile stress and strain at rupture. The equations are based on experimental results from tensile tests performed on coupons taken from roller bent wide flange sections which are presented in a companion paper. The newly obtained mechanical properties yield seven different full stress–strain curves for nine specific locations on the steel cross-section. The stress–strain models for the material of the flanges are defined by non-linear curves. The stress–strain characteristics in the web allow the material to be represented by bi-linear stress–strain curves. Comparison between predicted adjustments in mechanical properties due to roller bending and measured properties gives good agreement. The obtained stress–strain curves are suitable for implementation in finite element models for the analysis of arch structures employing beam, shell or solid elements.