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Title: Prediction of wear in grouted connections for offshore wind turbine generators
Authors: Dallyn, Paul A.
El-Hamalawi, Ashraf
Palmeri, Alessandro
Knight, R.
Keywords: Grouted connections
Integrity assessment
Offshore structures
Wear development
Wind turbines
Issue Date: 2017
Publisher: Elsevier Ltd on behalf of Institution of Structural Engineers (© The Authors)
Citation: DALLYN, P.A. ... et al, 2017. Prediction of wear in grouted connections for offshore wind turbine generators. Structures, 10, pp. 117-129.
Abstract: Insufficient axial capacity of large-diameter plain-pipe grouted connections has recently been observed in offshore wind turbine substructures across Europe. Aimed at understanding the implications of this phenomenon, a campaign of structural condition monitoring was undertaken. The measurements showed significant axial displacements occurring between the transition piece and the monopile, which in turn resulted in a considerable amount of wear. Given the existing lack of technical data on the implications that this relative movement has on the wear of grouted connections, a methodology was developed to quantify the likely risk to the foundation integrity of the wear failure mode. The proposed approach consists of a numerical model which applies the wear rate derived from previous experimental testing to the conditions experienced by typical offshore grouted connections, as indicated by the wind turbine generators' supervisory control and data acquisition systems. The output of this model showed that, for a representative sample of the wind farm substructures analysed as a case study, the accumulated lifetime wear would be minimal in the majority of the grouted connection, i.e. less than 0.4 mm over 75% of the connection, but a much greater loss in thickness, of the order of 4 mm, was predicted at the very top and bottom of the connection. This assessment is based on the assumptions that no significant changes occur in the surrounding environmental conditions and that the degradation in the grouted connection does not significantly affect the dynamic response of the foundation structure over its life span. Importantly, these assumptions may affect the model's predictions in terms of cumulated wear over time, not in terms of identifying the individual connections to be prioritised when performing remedial work, which is indeed the main intended use of the model.
Description: This is an Open Access article published by Elsevier and distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0). Further details are available here: https://creativecommons.org/licenses/by/4.0/
Sponsor: This study has been developed as part of the first author's EngD (Engineering Doctorate) project, co-sponsored by the ESPRC (the UK Engineering and Physical Sciences Research Council) (Grant code EP/G037272/1) and E.ON, whose financial support is gratefully acknowledged.
Version: Published
DOI: 10.1016/j.istruc.2017.02.001
URI: https://dspace.lboro.ac.uk/2134/24584
Publisher Link: http://dx.doi.org/10.1016/j.istruc.2017.02.001
ISSN: 2352-0124
Appears in Collections:Published Articles (Civil and Building Engineering)

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