Improved fully coupled peridynamic model for analyzing the compressive behaviour of concrete under sulfate attack

The interaction between sulfate attack and damage in concrete exhibits a strong coupling effect. As concrete primarily serves under compression, the presence of compression damage can accelerate its damage evolution when exposed to sulfate attack. Furthermore, the crack closure effect significantly influences the mechanical behaviour of the cracked surface after damage. However, current studies on the crack closure effect are insufficient. A model that considers this effect is necessary to investigate the damage evolution of concrete under the combination of sulfate attack and compressive loading. In this study, an improved fully coupled bond-based peridynamic (PD) model was developed by analyzing the closure characteristics of cracks in compressed concrete. The model considers the evolution of the mechanical behaviour of concrete after damage under compressive loading and sulfate attack. The bond forces in the improved fully coupled PD model were modified to consider material stiffness, which resists volume changes after damage, to allow for continued interaction and avoid intrusion between cracked surfaces. Several benchmark numerical examples are consistent with the experimental results, verifying the correctness and validity of the proposed improved fully coupled PD model.