Abstract Foundations for Offshore Wind Turbines (OWTs) are designed following the limit state philosophy. One of the considered states is the Serviceability Limit State (SLS), which verifies that the permanent rotation of the foundation generated from accumulated strains in the soil is below a project specific criterion. Despite design codes requiring an estimation of the permanent rotation, there is not clear guidance on how to implement this. This paper describes a methodology to estimate the monopile permanent rotation for SLS and discusses its advantages and limitations. The methodology combines an accumulation method with results from 3D Finite Element Analyses (FEA) and a soil model that accounts for strain accumulation as a function of the number of cycles, relative density and load characteristics. The performance of the proposed methodology is compared against experimental centrifuge tests and results from advanced 3D FEA, indicating that it can predict the permanent rotation with satisfactory accuracy, and with a considerable reduction in computational effort. This is important for the design of OWTs, where different load histories might be required to be checked – often under tight time constraints – to find which load history leads to the largest permanent rotation, and therefore is more critical to SLS design.

中文翻译：

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用于预测海上风力涡轮机沙子支撑中单桩永久旋转的程序

摘要 海上风力涡轮机 (OWT) 的基础是按照极限状态原理设计的。考虑的状态之一是适用性极限状态 (SLS)，它验证由土壤中累积应变产生的基础的永久旋转低于项目特定标准。尽管设计规范要求估计永久旋转，但没有关于如何实现这一点的明确指导。本文描述了一种估计 SLS 单桩永久旋转的方法，并讨论了它的优点和局限性。该方法将累积方法与 3D 有限元分析 (FEA) 的结果和土壤模型相结合，该模型将应变累积作为循环次数、相对密度和载荷特性的函数。将所提出的方法的性能与实验离心机测试和高级 3D FEA 的结果进行比较，表明它可以以令人满意的精度预测永久旋转，并显着减少计算工作量。这对于 OWT 的设计很重要，其中可能需要检查不同的负载历史——通常在时间紧迫的情况下——以找出导致最大永久旋转的负载历史，因此对 SLS 设计更为关键。