Durability design and construction enhancing of concrete structures in mesoscopic approach: A case study of a large-scale anchorage structure

The durability challenges in concrete infrastructure are complex, with difficulties in considering the multiscale material variation and multiphysics deterioration mechanism during long-term service. This study aims to investigate the structural durability from material scale and predict the probabilistic evolution of structural performance by numerical approach. This paper considers the influence of concrete mesostructure by mesoscopic modeling. For the actual large-scale concrete structure, the different durability problems and different environmental exposures are investigated comprehensively in numerical approaches. Based on the evaluation of reliability indices on structural durability, suggestions are proposed for the structural design and detailed protective measures. With the simulation with 0.1 mm element size and 3-hour time step, the durability deteriorations on the anchorage structure of the Shiziyang Link Project are analyzed, revealing chloride ingress depths, carbonation depths, and the occurrence of corrosion. For the atmospheric zone with a 50 mm concrete cover, carbonation is the governing factor leading the reinforcement corrosion, and the extreme frontal depth can reach 59.4 mm. For the splashing and tidal zone, the carbonation with an extreme depth of 53.0 mm is the major concern for durability, but the 70 mm concrete cover is thicker to protect the structure from local corrosion. For the immersed zone over 10 m underwater, the chloride ingress depth can reach 70 mm thickness of concrete cover after short service. By comparing the depth distributions with the thickness of the concrete cover, the failure probabilities of reinforcement corrosion of three zones can reach 65.5%, 0.0%, and 100%, respectively, after the 100-year service. To meet the restricted durability limit state requirement with under 1% of target corrosion probability, the service lives of three zones range from 6.1 years to over 100 years. The improvement solutions are presented and evaluated for anchorage structural durability. The change of aggregates from rounder shapes to slender shapes can reduce the deterioration depth by about 2.4%, and the probability of reinforcement corrosion under concrete cover can be reduced a lot. For the concrete joint, the recommended seal takes advantage of these basic types, and its resistance to the local carbonation in the joint is also verified by comparison.