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Predicting long term performance of Offshore Wind Turbines using Cyclic Simple Shear apparatus

Nikitas, Georgios, Arany, L, Aingaran, S, Vimalan, J and Bhattacharya, Subhamoy (2016) Predicting long term performance of Offshore Wind Turbines using Cyclic Simple Shear apparatus Soil Dynamics and Earthquake Engineering, 92. pp. 678-683.

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Abstract

Offshore wind turbine (OWT) foundations are subjected to a combination of cyclic and dynamic loading arising from wind, wave, 1P (rotor frequency) and 2P/3P (blade passing frequency) loads. Under cyclic/dynamic loading, most soils change their characteristics. Cyclic behaviour (in terms of change of shear modulus change and accumulation of strain) of a typical silica sand (RedHill 110) was investigated by a series of cyclic simple shear tests. The effects of application of 50,000 cycles of shear loading having different shear strain amplitude, cyclic stress ratio (ratio of shear to vertical stress), and vertical stress were investigated. Test results were reported in terms of change in shear modulus against the number of loading cycles. The results correlated quite well with the observations from scaled model tests of different types of offshore wind turbine foundations and limited field observations. Specifically, the test results showed that; (a) Vertical and permanent strain (accumulated strain) is proportional to shear strain amplitude but inversely proportional to the vertical stress and relative density; (b) Shear modulus increases rapidly in the initial cycles of loading and then the rate of increase diminishes and the shear modulus remains below an asymptote. Discussion is carried out on the use of these results for long term performance prediction of OWT foundations.

Item Type: Article
Subjects : Civil & Environmental Engineering
Divisions : Faculty of Engineering and Physical Sciences > Civil and Environmental Engineering
Authors :
NameEmailORCID
Nikitas, Georgiosgeorgios.nikitas@surrey.ac.ukUNSPECIFIED
Arany, LUNSPECIFIEDUNSPECIFIED
Aingaran, SUNSPECIFIEDUNSPECIFIED
Vimalan, JUNSPECIFIEDUNSPECIFIED
Bhattacharya, Subhamoys.bhattacharya@surrey.ac.ukUNSPECIFIED
Date : 17 November 2016
Identification Number : 10.1016/j.soildyn.2016.09.010
Copyright Disclaimer : © 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Uncontrolled Keywords : Cyclic Simple Shear, Offshore Wind Turbines, Stiffness
Related URLs :
Depositing User : Symplectic Elements
Date Deposited : 15 Sep 2016 08:50
Last Modified : 08 Aug 2017 08:11
URI: http://epubs.surrey.ac.uk/id/eprint/812178

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