Damage evolution and plasticity development of concrete materials subjected to freeze-thaw during the load process

Freeze-thaw has a severe degradation effect on concrete materials, especially in cold regions. The damage evolution and plasticity development of concrete materials subjected to freeze-thaw during the load process are essential to improve the frost durability of concrete structures. In this paper, a cohesion reduction parameter is proposed to improve the accuracy of previous damage constitutive models for concrete materials. The value of parameter is determined by a theoretical proof, which is verified by a series of simulations. Followed, freeze-thaw degradation models are established by previous research work to describe the freeze-thaw degradation behaviors on the mechanical properties of concrete materials. These degradation models are applied into the mentioned constitutive model to establish the freeze-thaw damage constitutive model, which can reflect the constitutive relationship of concrete materials subjected to freeze-thaw damage. Additionally, a series of simulations are carried out to obtain the stress-strain relationships of concrete materials subjected to freeze-thaw cycles by proposed model. The calculation results have a good fit with corresponding test results. Finally, the calculation results are discussed to investigate the mechanism of damage evolution and plasticity development of concrete materials subjected to freeze-thaw cycles during the load process.