Analytical and Experimental Investigation into Pre-Stressed Carbon Fiber Reinforced Polymer (CFRP) Fatigue Retrofits for Steel Waterway Lock-Gate Structures

Lock gates are an important part of the transportation infrastructure within the United States (US). Unfortunately, many existing lock gates have reached or exceeded their initial design lives and require frequent repairs to remain in service. Unscheduled repairs often increase as gates age, having a local economic impact on freight transport, which can create economic ripples throughout the nation. Metal fatigue is a key cause of unscheduled service interruptions, degrading lock gate components over time. Additionally, because lock gates are submerged during operation, crack detection prior to component failure can be difficult, and repair costs can be high. This paper presents an analytical and experimental investigation into fatigue damage within common lock gate geometries, as well as fatigue mitigation strategies with a focus on extending gate service lives. Detailed finite element analyses are combined with fatigue and fracture mechanics theories to predict critical fatigue regions within common gate details and develop retrofit strategies for mitigating fatigue cracking. Full-scale experimental fatigue testing of a critical lock gate component is conducted to provide a baseline for the evaluation of retrofit strategies. Retrofit strategies and issues in using carbon fiber reinforced polymer (CFRP) plates having optimized pre-stress levels are discussed.