Dynamic response in frequency and time domains of a floating foundation for offshore wind turbines

Zhang, Ruoyu; Tang, Yougang; Hu, Jun; Ruan, Shengfu; Chen, Chaohe

doi:10.1016/j.oceaneng.2012.12.015

Cited by 43 publications

(24 citation statements)

References 6 publications

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“…The IMISM method mainly includes four parts, with the major considerations and improvements listed as follows: a) Construct the whole model and analyze the dynamic response of the whole mode: Build the whole finite element model of a semi-submersible platform and calculate the wind-and waveinduced responses of the whole model [32][33][34][35].…”

Section: The Improved Multiple Interpolation Sub-model (Imism) Methodsmentioning

confidence: 99%

“…Details of this step can be seen in Section 4. Then, the generated wind velocity-time histories and wave height-time histories can be converted, respectively, to time series of wind and wave loads of the corresponding nodes based on the current standards [23,24] and the previous work [13,32,33]. An m-block division method in Section 4 is utilized to simply the short-term sea states for improving numerical efficiency.…”

Section: Procedures For the Whole Fatigue Damage Analysismentioning

confidence: 99%

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Fatigue assessment on local components of a semi-submersible platform subjected to wind and wave loads

Ma¹,

Zhou²,

Bao³

et al. 2018

J. vibroeng.

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The objective in this work is to assess fatigue damages on local components of a semi-submersible platform under combined actions of wind and wave loads in time domain. Some improvements are provided in the present study to improve the efficiency and accuracy of the whole evaluating process. Firstly, a combined wind and wave relationship as well as an innovative mixture simulation method are used to generate time series of random wind and waves. Moreover, an m-block division method is proposed to compress the number of the whole short-term sea states in the wind-wave scatter diagram. Then, with an improved multiple interpolation sub-model method, the structural stress responses of the local structural components are calculated as is in the whole model analysis. Finally, a modified rain-flow counting method is provided and validated to count the stress cycles efficiently and accurately. Thus, the short-and long-term fatigue damages are computed based on the S-N curve approach and the cumulative fatigue damage rule. In relative agreement with the numerical results by the traditional time-domain method and existing experimental data, these proposed improved methods are demonstrated to be applicable and efficient methods for fatigue damage analyses. All the fatigue damages on local components satisfy the specification requirements and the minimum value appears under the up wind-wave state, which is the proper working condition for a semi-submersible platform.

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Section: The Improved Multiple Interpolation Sub-model (Imism) Methodsmentioning

confidence: 99%

Section: Procedures For the Whole Fatigue Damage Analysismentioning

confidence: 99%

Fatigue assessment on local components of a semi-submersible platform subjected to wind and wave loads

Ma¹,

Zhou²,

Bao³

et al. 2018

J. vibroeng.

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show abstract

“…Adhikari and Bhattacharya [17] showed that the natural frequency of the turbine tower decreases with the decrease in stiffness of the foundation and the increase in axial load. Zhang et al [18] investigated the dynamic response of a floating foundation of a turbine in 60 m deepwater and pointed out that the semisubmersible floating foundation can work with significant wave height less than 4 m. Wei et al [19] computed the capacity of monopile-and jacketsupported wind turbines and found that structural response can be dominated by either the wind or the wave depending on structural characteristics and site conditions. Wang et al [20] studied the dynamic response of a monopile-supported wind turbine subjected to wind, wave, and earthquake actions and indicated that it is necessary to consider the combination of the three actions in the design of such a turbine.…”

Section: Introductionmentioning

confidence: 99%

Improvement on Structural Forms of Pile Group Foundations of Deepwater Bridges

Ren

Tang

et al. 2019

Shock and Vibration

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As long-span cross-sea bridges extend to deeper sea areas, the bridge pile tends to increase in its slenderness ratio and becomes more susceptible to waves. To improve the structural stability at the construction stage, this study analyses wave-induced response of foundations. The wave theory and the method used for computing wave forces on foundations are first introduced. Then, a pile group foundation is taken as the research object, and different pile lengths ranging from 16 m to 46 m are considered. The wave-induced response of the piles and the cap is calculated. After understanding the effect of the pile length, three optimized foundations are proposed with the aim of reducing the free length of the pile, and the corresponding finite element models are established to compare their wave-induced response. The results show that the displacement at the top of the foundation increases with the increase in the pile length until the cap partly emerges from water and so does the internal force at the bottom. Setting a constraint in the middle of the piles can reduce their free lengths and is favourable to the wave-induced response of the foundation except for the shearing force. A stronger constraint shows better effects on improvement of the stability of the foundation. The conclusions provide reference for optimization on pile foundations of deepwater bridges.

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“…Most semi-submersible FOWT platforms consist of three cylindrical columns linked together with a set of braces [3]. In order to minimize heave motions and accelerations, and to shift heave resonance periods out of the first-order wave energy range, heave plates are attached to the column base [4].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic coefficients and pressure loads on heave plates for semi-submersible floating offshore wind turbines: A comparative analysis using large scale models

López-Pavón

Souto-Iglesias²

2015

Renewable Energy

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a b s t r a c tHydrodynamic forces on heave plates for a semi-submersible floating offshore wind turbine are discussed herein. A model of one of the platform columns has been built. This allows for the fitting of either a plain solid plate or the real heave plate prototype design. The latter is equipped with a vertical flap at its edge. The influence of the flap on the hydrodynamic coefficients is investigated through a results comparison with the plain solid one. The model plate diameter is 1 m, thus becoming, to the authors' knowledge, the largest for which results have been published. Results from experiments, in which added mass and damping coefficients have been measured, are presented. This experimental campaign also comprised the direct measurement of dynamic pressures on both heave plates, a fundamental magnitude for the structural design, which, until now, had not been experimentally explored for this type of system. For comparative reasons, numerical simulations were also conducted following common industry standards, both with a wide-spread frequency domain panel method (WADAM) and a RANS CFD commercial code (ANSYS CFX). Finally, results are compared with literature and consistent non-dimensionalizations are sought, with the aim of making these results useful for preliminary design purposes. The authors believe this research could benefit the offshore wind industry by improving the hydrodynamic design of the concept.

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Dynamic response in frequency and time domains of a floating foundation for offshore wind turbines

Cited by 43 publications

References 6 publications

Fatigue assessment on local components of a semi-submersible platform subjected to wind and wave loads

Fatigue assessment on local components of a semi-submersible platform subjected to wind and wave loads

Improvement on Structural Forms of Pile Group Foundations of Deepwater Bridges

Hydrodynamic coefficients and pressure loads on heave plates for semi-submersible floating offshore wind turbines: A comparative analysis using large scale models

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