Dynamic soil-structure interaction issues of offshore wind turbines

Laszlo Arany, Subhamoy Bhattacharya, S. J. Hogan, John Macdonald

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

8 Citations (Scopus)

Abstract

One of the important design drivers for offshore wind turbine (OWT) structures is the fatigue life. In order for such structures to make worthwhile investments, they need to be in operation for 20-30 years after installation. The wind turbine and the foundation are subject to fatigue damage from environmental loading (wind, waves) as well as from cyclic loading imposed through the rotational frequency (1P) through mass and aerodynamic imbalances and from the blade passing frequency (3P) of the wind turbine. Through dynamic amplification and resonance, the fatigue damage suffered by the structure can severely increase if the natural frequency of the wind turbine gets close to the frequency of excitation, thereby reducing the service lifetime of the OWT. Therefore, predicting the first natural frequency is of paramount importance. In this paper a mechanical and mathematical model is presented, which provides a good initial estimate of the natural frequency of OWTs for conceptual design. The soil-structure interaction (SSI) is modelled through a set of springs, which also includes the crosscoupling between the lateral and rotational stiffness of the foundation. Approximate analytical formulae are given to approximate the natural frequency. The results are compared to measured data as well as results from similar software. The sensitivity of the natural frequency of the structure to the stiffness parameters of the foundation are analysed and discussed.

Original languageEnglish
Title of host publicationProceedings of the 9th International Conference on Structural Dynamics, EURODYN 2014
PublisherEuropean Association for Structural Dynamics
Pages3611-3617
Number of pages7
Volume2014-January
ISBN (Electronic)9789727521654
Publication statusPublished - 1 Jan 2014
Event9th International Conference on Structural Dynamics, EURODYN 2014 - Porto, Portugal
Duration: 30 Jun 20142 Jul 2014

Conference

Conference9th International Conference on Structural Dynamics, EURODYN 2014
CountryPortugal
CityPorto
Period30/06/142/07/14

Keywords

  • Cross stiffness
  • Euler-Bernoulli beam theory
  • Natural frequency
  • Offshore wind turbine
  • Sensitivity analysis
  • Soil-structure interaction

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  • Cite this

    Arany, L., Bhattacharya, S., Hogan, S. J., & Macdonald, J. (2014). Dynamic soil-structure interaction issues of offshore wind turbines. In Proceedings of the 9th International Conference on Structural Dynamics, EURODYN 2014 (Vol. 2014-January, pp. 3611-3617). European Association for Structural Dynamics.