Research on the influence of concrete damage in wharf structures under fatigue loads on chloride ion diffusion

• Revealing the influence of concrete on chloride ion diffusion performance at different damage levels expands a new perspective for assessing the durability of port structures. • An increase in fatigue load level induces a significant increase in chloride ion content at the same depth, revealing the critical impact of load level on chloride ion diffusion performance. • The use of ultrasonic quantification to study concrete damage is employed, deepening the understanding of the correlation between structural damage and chloride ion transport. • Successfully simulating thermodynamic diffusion and chloride ion diffusion based on FLAC software provides a feasible method for numerical simulation to validate experimental results. Harbor structures in marine environments are susceptible to fatigue damage from long-term berthing loads, which accelerates chloride ingress and causes steel corrosion, ultimately reducing the durability and performance of reinforced concrete structures. To investigate the influence of fatigue damage on chloride ion diffusion, this paper simulated the damage degradation process of structures under fatigue load and chloride ion penetration through experiments. Damage induced by fatigue loading was evaluated using ultrasonic methods, and the effects of varying stress levels and loading cycles on chloride ion transport were investigated. The chloride ion concentration profile under varying damage conditions was predicted through numerical simulation. The results indicate that fatigue loading increases both the applied stress level and the chloride ion content at a given depth. Repeated loading accelerates the penetration rate, which shows a positive correlation with chloride ion diffusivity. The chloride ion diffusion coefficient of concrete exhibits an exponential relationship with the level of fatigue damage. The numerical simulation results are consistent with the experimental findings, validating the feasibility of establishing a relationship between thermodynamic diffusion and chloride ion diffusion parameters using an analogy approach. This study supports the performance assessment and maintenance of reinforced concrete structures in marine environments.