The jacket substructure is a critical component of the offshore wind turbine (OWT) that is the interface between the transition piece at the top and the grouted connection. This paper presents a comprehensive study on the optimization of a jacket substructure to achieve greater cost efficiency while maintain acceptable structural performance. A fast parametric finite element modelling (FEM) approach for jacket substructures was firstly proposed. The generated models took into account realistic loading conditions, including self-weight, wind load and section-dependent wave load, and soil-pile interaction. Parametric studies were conducted afterwards to investigate the trends of the mass and response of the jacket substructure with respect to the variation of geometric and sectional parameters. Optimizations of the jacket substructure were carried out using parametric optimization and numerical genetic algorithm (GA) optimization under three different optimization strategies corresponding to three groups of objective and constraint functions. The trends obtained by parametric analysis were used to guide the parameter selection in parametric optimization, while a rank-based mutation GA was established with the proposed efficient FEM embedded in as the solver to the optimization objective and constraint functions. Parametric optimization gained its advantage in computational efficiency, and the mass reduction were 6.2%, 10% and 14.8% for the three strategies respectively. GA optimization was more aggressive as the mass reductions were 16.8%, 22.3% and 34.3% for the three strategies, but was relatively more computational intense. The two proposed optimization methods and the three optimization strategies are both expected to be applied in practical engineering design of OWT jacket substructure with good optimization output and high computational efficiency.

中文翻译：

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考虑实际边界和载荷条件的海上风力涡轮机导管架下部结构的高效分析和优化的数值工具

导管架下部结构是海上风力发电机 (OWT) 的关键部件，是顶部过渡件和灌浆连接之间的接口。本文对导管架下部结构的优化进行了全面的研究，以实现更高的成本效率，同时保持可接受的结构性能。首次提出了导管架下部结构的快速参数化有限元建模（FEM）方法。生成的模型考虑了实际荷载条件，包括自重、风荷载和与截面相关的波浪荷载以及土-桩相互作用。随后进行了参数研究，以研究导管架下部结构的质量和响应随几何和截面参数变化的趋势。在对应于三组目标和约束函数的三种不同优化策略下，使用参数优化和数值遗传算法（GA）优化对导管架下部结构进行优化。通过参数分析获得的趋势用于指导参数优化中的参数选择，同时建立了基于排序的突变遗传算法，并将所提出的高效有限元嵌入作为优化目标和约束函数的求解器。参数优化在计算效率方面具有优势，三种策略的质量减少分别为6.2%、10%和14.8%。 GA 优化更加积极，三种策略的质量减少分别为 16.8%、22.3% 和 34.3%，但计算量相对更大。所提出的两种优化方法和三种优化策略均有望应用于OWT导管架下部结构的实际工程设计中，具有良好的优化输出和较高的计算效率。