고정식 해상풍력터빈에 대한 지반-말뚝 상호작용과 세굴깊이를 고려한 Level II 신뢰성 해석

Abstract

Currently, multi-member lattice-type structures including jackets and tripods are being considered as one of good alternatives to monopile foundations for relatively deep water in the range of 25&#8211 50 m of water depth owing to their technical and economic feasibility. In this study, the reliability analysis of bottom-fixed offshore wind turbines with monopile and/or multi-member lattice-type foundations is carried out considering soil-pile interaction represented by nonlinear soil springs and scouring depth. The sensitivities of random variables such as material properties, external loadings are compared with respect to the foundation type and scouring depth. Response surface method is incorporated to handle the implicit type of a limit state function for applying the level-II reliability method, i.e. advanced first order second moment method. From the numerical analysis of the NREL 5 MW wind turbine models supported by monopile, tripod and jacket substructures, it is found that the souring depth can affect the reliability index more significantly for the monopile-supported OWTs while the reliability index is not so sensitive to the scouring depth in the cases of tripod- and jacket-supported OWTs.hnical and economic feasibility. In this study, the reliability analysis of bottom-fixed offshore wind turbines with monopile and/or multi-member lattice-type foundations is carried out considering soil-pile interaction represented by nonlinear soil springs and scouring depth. The sensitivities of random variables such as material properties, external loadings are compared with respect to the foundation type and scouring depth. Response surface method is incorporated to handle the implicit type of a limit state function for applying the level-II reliability method, i.e. advanced first order second moment method. From the numerical analysis of the NREL 5 MW wind turbine models supported by monopile, tripod and jacket substructures, it is found that the souring depth can affect the reliability index more significantly for the monopile-supported OWTs while the reliability index is not so sensitive to the scouring depth in the cases of tripod- and jacket-supported OWTs.