Structural stability and service life assessment of marine RC piles subjected to depth-dependent corrosion under lateral impacts

Reinforced concrete (RC) piles supporting harbour jetties and berthing structures are frequently subjected to lateral vessel impacts while exposed to aggressive marine environments. Conventional impact resistant design and durability assessments typically assume uniform corrosion or simplified end of life material reductions, neglecting spatially varying depth-dependent deterioration and its interaction with structural dynamics. This study presents a unified corrosion impact assessment framework to evaluate the long-term structural stability and service life of marine RC piles under lateral impacts. A depth-dependent multi-ion reactive corrosion model is integrated with a time-evolving multi-degree-of-freedom dynamic formulation to capture annual degradation of stiffness and mass, modal softening, and transient impact response over a 50-year service period. Both global responses, including pile head displacement and flexural capacity at mudline, and local damage mechanisms such as concrete bearing and steel yielding are evaluated using a consistent factor of safety criterion. Results show that corrosion concentrated in splash and tidal zones governs stiffness loss and modal degradation, producing displacement amplification exceeding 14 % and earlier attainment of flexural capacity under identical impact conditions. Operational measures such as reducing berthing velocity and low tide operations can extend service life by up to 34 % and 25 % respectively. • Coupled time-varying depth-dependent corrosion with MDOF impact dynamic model. • Uniform corrosion practices misestimate structural degradation and safety margins. • Corrosion amplifies lateral displacement by 14 % at end of the 50-year design life. • Parametric studies reveal optimal operational berthing conditions for ageing piles. • Accounting tidal variation and controlled berthing can extend service life by 34 %.