Underwater Inspection And Decision Analysis For Target Fatigue Lives

This paper proposes a methodology for fatigue design decision analysis which combines the probability of loss of the structure (which accounts for structural redundancy) and probability of fatigue failure of joints. This process could also include benefits arising from a monitoring plan. The method allows balancing of the initial cost of providing a stronger jacket and/or long-life joints with the future cost of monitoring and repairing if a joint fails. The method is suitable for decision making during the design process. The intention is to provide a simple but satisfactory procedure for the explicit balancing of costs and risk associated with adopting a particular design strategy. The method is an extension to the current practice for the fatigue design. As the method identifies the joints most critical to the structural integrity, it enables inspection effort to be concentrated where it can be more effective.