Risk-Based Maintenance of Lock Gates Based on Multiple Critical Welded Joints

AbstractIn many countries, inland waterway transport plays a significant role in the overall transport system. Navigation locks and dams are critical for inland waterways which regulate water and allow vessels to navigate. These infrastructures normally utilize large hydraulic steel structures, which are primarily of welded steel structures. Many of the critical welded joints of navigation lock gates have been in service for decades and are experiencing varying degrees of deterioration, mainly from fatigue. Inspection and maintenance of lock gates are expensive, generally requiring the complete closure of locks. Therefore, innovative strategies for the inspection and maintenance of lock gates are required. Fatigue cracks reflect the inherently poor fatigue performance of welded joints. Due to the cyclic loading nature of lock gates the fatigue of critical details requires assessment methods based on the reliability methods. Risk-based inspection planning are used for marine structures but seldom applied to inland navigation lock gates. This paper presents methods to update the failure probability of welded joints considering crack inspection data by using Dynamic Bayesian Network. Optimal inspection and repair plans can be evaluated by risk analysis, combining failure probabilities and associated expected costs for different events. In this study, a numerical example of the procedure of risk-based maintenance of a lock gate based on multiple critical welded joints is described. This reference case is a lock gate fabricated with five critical welded joints corresponding to different equivalent stress ranges. The conclusion is that risk-based maintenance of lock gates based on the optimization of the total expected cost is recommended.