Dynamic evolution of corrosion behaviour and degradation of mechanical performance of plane steel gates

The long-term operation of plane steel gates under cyclic dry–wet conditions results in complex corrosion behaviour and significant mechanical degradation, particularly under static hydraulic pressure. However, current studies are limited by insufficient field data and the inability of laboratory tests to fully replicate in-service environments. To better understand the dynamic corrosion processes of steel gates, a cellular automata model was employed to simulate the time-dependent evolution of corrosion morphology. The model's accuracy was validated through comparison with experimental results. Furthermore, a finite element model incorporating corrosion-induced damage was established to evaluate the effects of corrosion on structural performance. Results show that the uniform corrosion rate exhibits an initial exponential increase before stabilising due to surface blockage by corrosion products. In contrast, pitting corrosion accelerates in the depth direction, driven by localised autocatalytic reactions. Uniform corrosion gradually reduces global structural integrity, while localised corrosion poses a higher risk of through-thickness penetration and early failure. These findings contribute to a more reliable basis for assessing the durability and maintenance needs of hydraulic steel structures operating in aggressive service conditions.