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Modeling of Load Bearing Characteristics of Jacket Foundation Piles for Offshore Wind Turbines in Taiwan
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Energies 2016, 9(9), 734; doi:10.3390/en9090734

Axial Dynamic Stiffness of Tubular Piles in Viscoelastic Soil

Department of Civil Engineering, Aalborg University, Sofiendalsvej 11, 9200 Aalborg SV, Denmark
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Academic Editor: Lance Manuel
Received: 22 June 2016 / Revised: 20 August 2016 / Accepted: 24 August 2016 / Published: 10 September 2016
(This article belongs to the Collection Wind Turbines)
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Abstract

Large offshore wind turbines are founded on jacket structures. In this study, an elastic full-space jacket structure foundation in an elastic and viscoelastic medium is investigated by using boundary integral equations. The jacket structure foundation is modeled as a hollow, long circular cylinder when the dynamic vertical excitation is applied. The smooth surface along the entire interface is considered. The Betti reciprocal theorem along with Somigliana’s identity and Green’s function are employed to drive the dynamic stiffness of jacket structures. Modes of the resonance and anti-resonance are presented in series of Bessel’s function. Important responses, such as dynamic stiffness and phase angle, are compared for different values of the loss factor as the material damping, Young’s modulus and Poisson’s ratio in a viscoelastic soil. Results are verified with known results reported in the literature. It is observed that the dynamic stiffness fluctuates with the loss factor, and the turning point is independent of the loss factor while the turning point increases with load frequency. It is seen that the non-dimensional dynamic stiffness is dependent on Young’s modulus and Poisson’s ratio, whilst the phase angle is independent of the properties of the soil. It is shown that the non-dimensional dynamic stiffness changes linearly with high-frequency load. The conclusion from the results of this study is that the material properties of soil are significant parameters in the dynamic stiffness of jacket structures, and the presented approach can unfold the behavior of soil and give an approachable physical meaning for wave propagation. View Full-Text
Keywords: offshore foundation; mathematical model; boundary integral; damping in viscoelastic media; resonance offshore foundation; mathematical model; boundary integral; damping in viscoelastic media; resonance
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Bayat, M.; Andersen, L.V.; Ibsen, L.B. Axial Dynamic Stiffness of Tubular Piles in Viscoelastic Soil. Energies 2016, 9, 734.

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