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Earthquake Engineering and Engineering Vibration

, Volume 17, Issue 4, pp 893–901 | Cite as

A simplified method for analyzing the fundamental frequency of monopile supported offshore wind turbine system design

  • Chunbao Yang
  • Rui Wang
  • Jianmin Zhang
Article
  • 48 Downloads

Abstract

Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange’s Equation, this study establishes a simple formula for the analysis of system fundamental frequency in the preliminary design of an offshore wind turbine with a monopile foundation. This method takes into consideration the variation of cross-section geometry of the wind turbine tower along its length, with the inertia moment and distributed mass both changing with diameter. Also the rotational flexibility of the monopile foundation is mainly considered. The rigid pile and elastic middle long pile are calculated separately. The method is validated against both FEM analysis cases and field measurements, showing good agreement. The method is then used in a parametric study, showing that the tower length Lt, tower base diameter d0, tower wall thickness δt, pile diameter db and pile length Lb are the major factors influencing the fundamental frequency of the offshore wind turbine system. In the design of offshore wind turbine systems, these five parameters should be adjusted comprehensively. The seabed soil condition also needs to be carefully considered for soft clay and loose sand.

Keywords

offshore wind turbine system fundamental frequency analytical method rotational foundation flexibility 

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Notes

Acknowledgement

The authors gratefully acknowledge support for this research from the National Natural Science Foundation of China (Grant Nos. 51678346 and 51038007), and the State Key Laboratory of Hydroscience and Engineering Project (Grant Nos. 2014-KY-03 and 2015-KY-03).

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Copyright information

© Institute of Engineering Mechanics, China Earthquake Administration and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.School of Civil Engineering/State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic EngineeringTsinghua UniversityBeijingChina

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