{"title":"Effect of the transition piece on the natural frequencies of monopile-supported offshore wind turbines","authors":"","doi":"10.1016/j.soildyn.2024.108982","DOIUrl":null,"url":null,"abstract":"<div><div>The lateral natural frequency of an offshore wind turbine (OWT) is a crucial factor to consider in the design of OWT foundations. Eighty percent of currently installed OWTs are mounted on monopile foundations, which are connected to the superstructure via a transition piece (TP). To explore the differences in natural frequencies between grouted connection (GC) and TP-less designs, this study incorporates a transition piece into the calculation model of the OWT system. Based on the Timoshenko beam theory and transfer matrix method, the characteristic equations of the lateral natural frequency of the OWT are derived. The study found that the effect of the transition piece on the natural frequency is strongly influenced by the OWT type and the soil stiffness, and the influence of transition piece on different order natural frequencies is different for the same OWT. For the NREL offshore 5-MW baseline wind turbine, the TP-less model reduces the first natural frequency of the OWT by 1.31 % and elevates the second and third natural frequencies by 11.88 % and 2.72 %, respectively, compared to the GC model. The increase in soil shear wave velocity amplifies the influence of the transition piece on the first and third natural frequencies, while weakening its influence on the second natural frequency.</div></div>","PeriodicalId":49502,"journal":{"name":"Soil Dynamics and Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":4.2000,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Soil Dynamics and Earthquake Engineering","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0267726124005347","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, GEOLOGICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The lateral natural frequency of an offshore wind turbine (OWT) is a crucial factor to consider in the design of OWT foundations. Eighty percent of currently installed OWTs are mounted on monopile foundations, which are connected to the superstructure via a transition piece (TP). To explore the differences in natural frequencies between grouted connection (GC) and TP-less designs, this study incorporates a transition piece into the calculation model of the OWT system. Based on the Timoshenko beam theory and transfer matrix method, the characteristic equations of the lateral natural frequency of the OWT are derived. The study found that the effect of the transition piece on the natural frequency is strongly influenced by the OWT type and the soil stiffness, and the influence of transition piece on different order natural frequencies is different for the same OWT. For the NREL offshore 5-MW baseline wind turbine, the TP-less model reduces the first natural frequency of the OWT by 1.31 % and elevates the second and third natural frequencies by 11.88 % and 2.72 %, respectively, compared to the GC model. The increase in soil shear wave velocity amplifies the influence of the transition piece on the first and third natural frequencies, while weakening its influence on the second natural frequency.
期刊介绍:
The journal aims to encourage and enhance the role of mechanics and other disciplines as they relate to earthquake engineering by providing opportunities for the publication of the work of applied mathematicians, engineers and other applied scientists involved in solving problems closely related to the field of earthquake engineering and geotechnical earthquake engineering.
Emphasis is placed on new concepts and techniques, but case histories will also be published if they enhance the presentation and understanding of new technical concepts.