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1

Evaluation of sand p–y curves by predicting both monopile lateral response and OWT natural frequency

Amel Douifi, Djillali Amar Bouzid, Subhamoy Bhattacharya, Nasreddine Amoura

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 1

66--81

EN

Extending the use of the p–y curves included in the regulation codes API and DNV to design large-diameter monopiles supporting offshore wind turbines (OWTs) was unsuccessful as it resulted in an inaccurate estimation of the monopile behavior. This had prompted many investigators to propose formulations to enhance the performances of Winkler model. In this paper, two case studies are considered. A case consisting of an OWT at Horns Rev (Denmark) supported by a monopile in a sandy soil was studied first. Taking the FEA using ABAQUS as reference, results of WILDOWER 1.0 (a Winkler computer code) using the recently proposed p–y curves giving design parameters were plotted and evaluated. In order to see the ability of proposed p–y curves to predict the monopile head movements, and consequently the first natural frequency (1st NF), a second case study consisting of a monopile supporting an OWT at North Hoyle (UK) was selected. The monopile head stiffness in terms of lateral, rocking, and cross-coupling stiffness coefficients, necessary for the 1st NF, were computed using both ABAQUS and WILDPOWER 1.0. Comparisons with the measured 1st NF showed that with the exception of one p–y model, none of other proposed Winkler methods is able to predict accurately this parameter.

2

The influence of selected strain-based failure criteria on ship structure damage resulting from a collision with an offshore wind turbine monopile

Niklas Karol, Bera Alicja

Polish Maritime Research

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2021

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nr 4

42--52

EN

Offshore wind farms are developing well all over the world, providing green energy from renewable sources. The evaluation of possible consequences of a collision involves Finite Element computer simulations. The goal of this paper was to analyse the influence of selected strain-based failure criteria on ship damage resulting from a collision with an offshore wind turbine monopile. The case of a collision between an offshore supply vessel and a monopile-type support structure was examined. The results imply that simulation assumptions, especially the failure criteria, are very important. It was found that, using the strain failure criteria according to the minimum values required by the design rules, can lead to an underestimation of the ship damage by as much as 6 times, for the length of the hull plate, and 9 times, for the area of the ship hull opening. Instead, the adjusted formula should be used, taking into account both the FE element size and the shell thickness. The influence of the non-linear representation of the stress-strain curve was also pointed out. Moreover, a significant influence of the selected steel grade on collision damages was found.

3

Short review and 3-D FEM analysis of basic types of foundation for offshore wind turbines

Iwicki Piotr, Przewłócki Jarosław

Polish Maritime Research

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2020

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nr 3

31--39

EN

Some problems of the foundations of offshore wind turbines are considered in this paper. A short review is presented on the two basic types of foundations, i.e. monopiles and gravity foundations, including their basic features and applications as well as general design considerations. Also, some issues regarding analysis are discussed, including geotechnical problems and modelling techniques. A numerical model of offshores turbine and some preliminary computations are presented. Finite element analysis was carried out for wind turbines supported on both gravity and monopile foundations. The wind turbine tower, blades (simplified model), gravity foundation and part of the surrounding soil are included in the model. The turbine was loaded by wind and loads induced by waves, inertia and gravity. Both non-linear static and dynamic analysis of the wind turbine was performed. The displacements and stresses under the tower foundations were calculated and a comparison analysis carried out.

4

Rozwiązania fundamentów stosowane dla linii 400 kV na terenie Angoli i Anglii

Pióro Krzysztof, Cempura Grzegorz, Sobień Dorota

Energetyka

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2019

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nr 8

549--553

PL

Przedstawiono problem posadowienia słupów energetycznych w zróżnicowanych warunkach geologicznych na przykładzie dwóch zagranicznych projektów realizowanych w Angoli oraz w Anglii. Opisano kilka rzadko spotykanych na polskim rynku rozwiązań konstrukcyjnych. Zdobyte cenne doświadczenie inżynierskie jest wykorzystywane w kolejnych realizacjach.

EN

Presented is the problem concernig foundation of electric power pillars in various gelogical conditions on the example of two foreign investment projects realized in Angola and England. Described are some of the construction solutions rarely found in Poland. The valuable experince gained then is used in subsequent projects.