Damage constitutive model for concrete under the coupling action of freeze-thaw cycles and load based on homogenization theory

The constitutive properties of concrete in freeze-thaw (F-T) environments are the basis for evaluating whether its mechanical properties are adequate for engineering practice in cold regions. The aim of this paper is to establish a constitutive model considering F-T damage and mesoscopic structural damage during loading to effectively predict the mechanical properties of freeze-thawed concrete. Firstly, concrete is conceptualized as the structural body and the frictional band at the mesoscale, based on which the F-T damage mechanism and the load damage mechanism of concrete are analyzed. Then, the macro-mesoscopic constitutive relationship is established based on the mean-field homogenization method. The constitutive properties of the structural body and the frictional band are defined as elastic and elastoplastic, respectively. The damage evolution equation under the coupling action of F-T cycles and load is developed based on the damage mechanism of concrete. In addition, inhomogeneous deformations between the structural body and the frictional band are considered in the model. Finally, the rationality of the proposed model is demonstrated by the test results of the frozen-thawed concrete. The deterioration characteristics of F-T cycles can be well reproduced.