Finite element modelling and analysis of a reinforced concrete beam bridge structure

This article presents a numerical study of a reinforced concrete beam-and-slab bridge span carried out using the finite element method (FEM). The analysed span consists of a slab and longitudinal ribs, with geometry and reinforcement based on a previously tested prototype. The ribs are reinforced longitudinally from 12 mm to 20 mm bars in five samples and transversely with 5 mm stirrups at 100 mm spacing, while the slab contains a 5 mm bar mesh with 50 mm spacing in both directions. A three-dimensional nonlinear FEM model was created, including material nonlinearity of concrete and reinforcing steel and realistic boundary conditions. The bridge span was analysed under static loads from 10.8 kN up to an ultimate load of 36 kN, and the results were compared with available experimental data. Stress and strain distributions, load-strain relationships, crack patterns and mid-span deflections were obtained for several configurations with different diameters of tensile reinforcement. The study shows how a gradual reduction of reinforcement diameter from 20 mm to 12 mm affects stiffness, strain levels and the serviceability limit state of the span, and demonstrates the potential of FEM for assessing the behaviour and safety of existing or reconstructed bridge structures.