Abstract Design and operation of large welded structural systems (e.g. ship and offshore structures) are challenging due to numerous fatigue-sensitive details, limited available budgets, uncertainties in fatigue damages, inspection & maintenance activities, etc. Traditionally, fatigue design and maintenance planning have been almost disconnected, which restricts coherent decision-making and optimum safety management. Structural design optimization, without quantitatively incorporating the effects of operational maintenance, can hardly result in a structural plan that is optimum in terms of life cycle costs. Also, if the design of a structure is not optimum, maintenance optimization alone cannot really yield a optimum maintenance plan. As operational inspections and maintenance are essential, there are merits to utilize their effects on structural design and meanwhile optimize them at the initial design stage when impacts of decisions are greater. This paper proposes a risk-based approach to holistic decision-making enveloping decisions and uncertainties affecting design, inspection and maintenance of fatigue-sensitive components. Decisions variables in structural scantling and operational maintenance are obtained holistically at the structural design stage by risk-based optimization, based on quantitative assessment of the effectiveness of both structural scantling and maintenance interventions. Optimum fatigue reliability level is also obtained, informed by the effects of uncertainties and failure consequences. The method captures combined benefits of structural scantling and operational maintenance to fatigue reliability and risk mitigation and achieves optimum resource utilization and life cycle cost reduction. Advantages of the proposed method have been demonstrated via a numerical example, in comparison to alternative methods.

中文翻译：

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基于风险的疲劳敏感结构检查和设计决策的整体方法

摘要 大型焊接结构系统（例如船舶和海上结构）的设计和操作由于大量疲劳敏感细节、可用预算有限、疲劳损坏的不确定性、检查和维护活动等而具有挑战性。传统上，疲劳设计和维护计划具有几乎断开连接，这限制了连贯的决策和最佳的安全管理。结构设计优化，如果不定量地结合运营维护的影响，就很难得出在生命周期成本方面最优的结构计划。此外，如果结构设计不是最佳的，仅靠维护优化并不能真正产生最佳的维护计划。由于操作检查和维护是必不可少的，利用它们对结构设计的影响，同时在决策影响较大的初始设计阶段对其进行优化是有好处的。本文提出了一种基于风险的整体决策方法，包括影响疲劳敏感部件设计、检查和维护的决策和不确定性。结构尺寸和运营维护的决策变量是在结构设计阶段通过基于风险的优化，基于对结构尺寸和维护干预有效性的定量评估而整体获得的。根据不确定性和失效后果的影响，还可以获得最佳疲劳可靠性水平。该方法结合了结构尺寸和操作维护对疲劳可靠性和风险缓解的综合好处，并实现了最佳资源利用和生命周期成本降低。与替代方法相比，已通过数值示例证明了所提出方法的优点。