Cohesive fracture and probabilistic damage analysis of freezing-thawing degradation of concrete

The durability of concrete with low-degradation aggregates due to cyclic freezing and thawing effect is experimentally studied by characterizing the variance of fracture energy with respect to the number of freeze/thaw (F/T) cycles. Cohesive fracture test is conducted for notched concrete beams subjected to different F/T cycles, and the fictitious crack model-based approach is employed to calculate the fracture energy from the testing data. The relationship between the relative fracture energy and the number of F/T cycles is established using the nonlinear regression analyses. Based on the three-parameter Weibull distribution model, the probabilistic damage analysis is conducted, and the life distribution diagrams are produced according to the probability of reliability/survival concept. The relationships between the life (i.e., the number of F/T cycles) and damage parameter for different probabilities of reliability are obtained, from which the service life of concrete due to cyclic freezing and thawing actions can be determined at any given reliability index. The validation and accuracy of the present models are demonstrated through comparisons between the predicted data by the present models and the test data. The present probabilistic damage model can serve as a reference for maintenance, design and life prediction of concrete structures with low-degradation aggregates in cold regions subjected to cyclic freezing and thawing actions.