Constitutive model of concrete damaged by freeze–thaw action for evaluation of structural performance of RC elements

The coupled environmental-mechanical damage model extended by the authors to include the degradation effects on structural behavior of RC structures due to freezing-and-thawing cycles (FTC) is reformulated and generalized in the present work in order to better simulate the different aspects of the physical phenomenon. In particular the model is modified to consider separately the effect of FTC respectively on compressive and tensile strength and a new relationship to properly evaluate the equivalent number of FTC is proposed. To validate the model, an experimental campaign carried out on simply supported beams subjected to FTC is simulated. By comparing obtained numerical results with experimental evidence, the model is proved to be suitably accurate in reproducing the main aspects observed during tests: failure load, ultimate displacement, and failure mode. Actually the enhancement of freeze and thaw – mechanical model gives the base for the definition of a reliable numerical tool for analysis of RC structures subjected to FTC.