Offshore structures have a long service life and involve high cost. However, the working environment of offshore structures is harsh. When an accident occurs, it causes an adverse social impact and economic loss. Therefore, in the design process of offshore structures, in order to enhance their safety, this is an important problem that needs attention. Reliability-based design and optimisation (RBDO) using saddlepoint approximation (SA) is a powerful method to enhance the reliability of offshore structures. The SA utilises a cumulant generating function and saddlepoint to approximately express the probability density function and cumulative distribution function of a limit-state function. To further improve the accuracy of reliability evaluation in RBDO with SA, in this study, a mean-value second-order SA (MVSOSA) is introduced. A RBDO with MVSOSA strategy is proposed for the design problem of a wellhead platform. An engineering case study illustrates the application of the proposed method.

中文翻译：

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基于鞍点近似的海上结构基于可靠性的优化

离岸结构使用寿命长且成本高。但是，海上结构的工作环境恶劣。发生事故时，会对社会造成不利影响，并造成经济损失。因此，在海上结构的设计过程中，为了提高其安全性，这是一个需要注意的重要问题。使用鞍点近似（SA）的基于可靠性的设计和优化（RBDO）是增强海上结构的可靠性的强大方法。SA利用累积量生成函数和鞍点来近似表示极限状态函数的概率密度函数和累积分布函数。为了进一步提高带有SA的RBDO中可靠性评估的准确性，本研究引入了平均值二阶SA（MVSOSA）。针对井口平台的设计问题，提出了一种具有MVSOSA策略的RBDO。工程案例研究说明了该方法的应用。