Saltwater flooding-induced corrosion and lateral strength of reinforced concrete structures

Many coastal communities are located in areas of high seismic activity.Saltwater flooding can exacerbate the corrosion of lateral force-resisting systems of structures in these communities, impacting their seismic resilience.Evaluating the compounding risk from flood and seismic hazards in these communities is a necessary step toward ensuring the safety of coastal populations and infrastructure.This paper studies the loss of rebar in coastal reinforced concrete buildings over time due to both atmospheric and saltwater flooding-related corrosion and evaluates their effects on the performance of the lateral load resistance of these buildings.A previously developed corrosion model was modified to incorporate the impacts of annual coastal flooding on the corrosion rate.Finite element models of a reinforced concrete moment frame were created with rebar cross-sectional areas corresponding to various levels of corrosion.Pushover analyses were performed to determine the lateral strength and ultimate displacement capacity under different scenarios: atmospheric corrosion only, lower-and upper-bound corrosion rate changes due to flooding, corrosion of exterior columns or all columns due to flooding, and varying exposure durations (60 years or 80 years).The results show that although atmospheric corrosion does not lead to considerable change in lateral response, annual coastal flooding may result in up to 26% loss in lateral strength and up to 83% loss in displacement capacity.When the post-cracking corrosion rate is assumed to be four times higher than the pre-crack corrosion rate, the strength loss for buildings where all first-floor columns flooded becomes significant (>20%) over an 80-year period.In contrast, the displacement capacity loss is more sensitive to corrosion; even when the corrosion rate is assumed to simply double after cracking, with only the exterior columns exposed to seawater, displacement capacity decreases significantly (>10%) after 60 years.