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Geotechnical fragility analysis of monopile foundations for offshore wind turbines in extreme storms

Lookup NU author(s): Dr Tom CharltonORCiD, Dr Mohamed Rouainia



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2021 The AuthorsOffshore wind turbines (OWTs) must withstand harsh environmental loads over their 20- to 30-year design life. Fragility analysis investigates the probability of damage over a range of hazard intensities and is integral to a performance-based engineering approach. The focus of this paper is on monopiles, which are widely used to support OWTs in water depths up to around 40m. The paper presents a fragility analysis of monopiles in extreme storms in terms of geotechnical performance, measured by permanent rotation of the foundation. Geotechnical fragility has so far not been comprehensively addressed due to the challenge of predicting soil behaviour under cyclic loading and estimating the probability of extreme responses. On the latter, the paper develops efficient Karhunen-Loeve representations of wind and wave loading that can be combined with inexpensive probabilistic methods to compute fragility. The framework was demonstrated using a representative scenario of a 5 MW OWT installed in clay. Non-linear foundation response was captured by a dynamic 3D finite element model. Fragility curves were generated using subset simulation for storms with return periods (RPs) from 1 to 100 years. Fragility during extreme storms (with 50- and 100-year RPs) was significantly higher than storms with RPs of 10 years or less.

Publication metadata

Author(s): Charlton TS, Rouainia M

Publication type: Article

Publication status: Published

Journal: Renewable Energy

Year: 2022

Volume: 182

Pages: 1126-1140

Print publication date: 01/01/2022

Online publication date: 05/11/2021

Acceptance date: 29/10/2021

Date deposited: 14/12/2021

ISSN (print): 0960-1481

ISSN (electronic): 1879-0682

Publisher: Elsevier Ltd


DOI: 10.1016/j.renene.2021.10.092


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Funder referenceFunder name
first author's PhD research, which was funded by an EPSRC CASE studentship with Atkins.
Support from the EPSRC Collaborative Computational Project in Wave Structure Interaction (CCP–WSI) is also acknowledged (EP/T026782/1).