Comprehensive assessment of prestress loss in post-tensioned prestressed concrete structures exposed to wet-dry cycles in chloride environments

The shrinkage, creep of concrete, and relaxation of prestressing tendons lead to prestress loss in prestressed concrete (PC) structures under conventional environments. The prestress loss of PC structures is also affected by corrosive environments resulting from alternating wet and dry. Therefore, a new model for predicting prestress loss under alternating damp and dry chloride environments is proposed. The model considers the coupled effects of corrosion on concrete creep and the remaining cross-sectional area of steel reinforcement/prestressing tendons. A 300-day experimental study is conducted on a series of post-tensioned prestressed concrete beams subjected to a cyclic wet-dry corrosive environment to discuss prestress loss. The effectiveness of the model is verified through experimental results. The results indicate that the existing codes underestimate the long-term prestress loss of PC structures in corrosive environments . The proposed model can accurately predict the long-term prestress loss of PC beams. Compared with conventional environments, the creep coefficient of concrete under a dry-wet alternating corrosive environment increases by 15 %, resulting in a 12.4 % increase in the long-term prestress loss of the structure.