Fatigue life assessment of corrosion-damaged weathering steel bridge girders

Owing to its superior atmospheric corrosion resistance and low maintenance requirements, weathering steel is widely used in steel bridges and is often preferred by bridge owners over painted steel. However, recent studies have reported localized metal loss and perforation in weathering steel bridge members, raising concerns about the structural integrity, durability, and overall service life of these systems. These concerns are further amplified when corrosion damage coupled with fatigue is considered in the assessment of the service durability of steel bridges. At present, design guidelines do not provide an explicit approach for predicting the service life of steel structures in general, and weathering steel members in particular, that accounts for corrosion damage. In this study, we propose a practical framework that can be readily implemented to estimate the reduction in fatigue life of weathering steel girders due to corrosion damage. Since direct assessment of corrosion-induced damage in steel girders is cumbersome, the corrosion product mass ratio, α / γ ∗ , is used to correlate the corrosion rate of weathering steel with patina mineralogy, providing a framework for estimating fatigue life without reliance on long-term environmental monitoring. The estimated corrosion rate is then used to predict the corresponding reduction in fatigue life due to uniform corrosion and the effects of pitting corrosion. The proposed framework provides a simple and practical approach for evaluating the remaining fatigue performance of weathering steel bridge girders and serves as a useful tool for bridge inspection, maintenance planning, and life-cycle assessment.