Finite Element modelling of cracking behaviour of reinforced concrete tensile members using a combined phase field and cohesive zone modelling approach

The modelling of cracking behaviour of reinforced concrete (RC) structures represents an intricate challenge because of the heterogeneity of the concrete properties and the complex relationship between concrete and its reinforcement.While experimental methods are limited to inspecting deformations and cracks merely on the concrete's surface, analytical approaches usually assume simplifications as homogeneity of the concrete properties or constant deformation along the concrete section.Concrete's heterogeneous nature, where crack nucleation and propagation are governed by local material properties, introduces uncertainty in mechanical behaviour affecting structural safety, making finite element modelling with varying material properties more suitable for accurately capturing these effects.The focus of this study is to develop a numerical tool capable of predicting the cracking behaviour of concrete elements reinforced with steel bars subjected to tension.To that aim, finite element models were developed in ABAQUS using a phase field approach to simulate a RC tie element with a single centred steel bar.A stochastic random field was implemented to account for the variability of the concrete's tensile strength.Furthermore, the effectiveness of several techniques to model the concrete-to-steel bond such as a bilinear cohesive interface interaction and a rib-scale model was evaluated.Numerical models with different material field configurations were used to investigate the in-depth variability in cracking patterns and deformations.The numerical results were compared with available experimental results in the literature to validate the proposed model, confirming that the method can effectively model the mechanical behaviour and predict the crack formation stage of RC elements under tensile loading.