A new multiscale steel-concrete bond model for structural dynamics applications

International audienceThe robust characterization of the mechanical behavior for some reinforced concrete structures, such as the auxiliary buildings of nuclear plants, can be a major challenge. Therefore, it is necessary to identify the different energy dissipation sources: viscous dissipation, numerical dissipation due to the temporal integration scheme, and material dissipation that includes the interaction between concrete and steel reinforcement bars. Indeed, the energy dissipation along the steel-concrete interface may account up to 15% of the total material energy dissipation (Aguilera, 2016). In addition, the consideration of this steel-concrete interface in numerical modeling has a notable importance in the realistic estimation of the cracking process and stress redistribution. The various numerical strategies proposed in the literature are not sufficient to provide an accurate cracking prediction at the local level of the interface (cracks spacing and opening) (Phan et al., 2015) Furthermore, applying these methodologies for large scale structures is time consuming and has a high numerical cost (Mang et al., 2015). Therefore, the main objective of this study is to propose an original modeling strategy to take into account the behavior of the steel-concrete bond for structural applications. A multi-scale approach with internal degrees of freedom is proposed. It consists in using a macro-element capable of reproducing the behavior of steel and steel-concrete interface connected by means of interface stresses. This macro-element is inspired by an initial formulation proposed in (Sahyouni et al., 2022) to model a rigid inclusion encased in a soil volume. In the present work, this initial formulation is further developed and adapted to the steel-concrete interface problematic. Cyclic bond laws are considered, which allows a representation of the interface for cyclic and dynamic structure applications. Structural case studies are performed, showing a good reproduction of the experimental behavior of reinforced concrete elements