Comparison of Ice-induced Vibrations on a Conical and a Cylindrical Offshore wind Turbine Substructure

Vilho Jussila, Jaakko Heinonen

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review


    In the Gulf of Bothnia, the shallow coastline and the consistent wind conditions provide a good environment for the wind energy production. Relatively thick ice fields and low drifting ice field velocities, up to 0.6 m and 0.15 m/s respectively, are the dominating ice characteristics in the same area. The establishing of an offshore wind turbine in the cold regions requires a careful study on the structural response of ice-induced vibrations. Ice-substructure interaction was studied for a conical and a cylindrical monopile. The dominating ice failure mechanism for the conical substructure is bending. On the other hand, various ice interaction processes occur for the cylindrical substructure, e.g. the lock-in vibration, intermittent crushing and continuous brittle ice crushing. A dynamic ice load for the conical substructure was created with an external algorithm and implemented as a time-dependent loading in the finite element procedure. This ice load model is founded on earlier studies of Kärnä et al. (2004). The cylindrical substructure was analyzed by PSSII a special purpose soil-ice-interaction program developed for a vertical offshore substructure. Ice thickness and velocity were parameterized for both substructures. In addition, various configurations were studied by varying the cone angle and the foundation depth. According to the results, the conical substructure introduces a significant reduction in the vibration amplitudes compared to the cylindrical case. However, when the ice field thickness increases, the vibration amplitudes were observed to increase for the both substructures. The different ice interaction processes, depending on the foundation depth and the ice conditions, e.g. the ice thickness and velocity, are addressed.
    Original languageEnglish
    Title of host publicationProceedings of 21st IAHR International Symposium on Ice
    Subtitle of host publicationIce Research for a Sustainable Environment
    EditorsZhijun Li, Peng Lu
    Place of PublicationDalian, China
    Publication statusPublished - 2012
    MoE publication typeA4 Article in a conference publication
    Event21st IAHR International Symposium on Ice - Dalian, China
    Duration: 11 Jun 201215 Jun 2012


    Conference21st IAHR International Symposium on Ice


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