scholarly journals Reliability analysis of offshore wind turbine foundations under lateral cyclic loading

2020 ◽  
Vol 5 (4) ◽  
pp. 1521-1535
Author(s):  
Gianluca Zorzi ◽  
Amol Mankar ◽  
Joey Velarde ◽  
John D. Sørensen ◽  
Patrick Arnold ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Wind Turbine ◽  
Limit State ◽  
Large Diameter ◽  
Probabilistic Approach ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Fe Model ◽  
Foundation Design

Abstract. The design of foundations for offshore wind turbines (OWTs) requires the assessment of long-term performance of the soil–structure interaction (SSI), which is subjected to many cyclic loadings. In terms of serviceability limit state (SLS), it has to be ensured that the load on the foundation does not exceed the operational tolerance prescribed by the wind turbine manufacturer throughout its lifetime. This work aims at developing a probabilistic approach along with a reliability framework with emphasis on verifying the SLS criterion in terms of maximum allowable rotation during an extreme cyclic loading event. This reliability framework allows the quantification of uncertainties in soil properties and the constitutive soil model for cyclic loadings and extreme environmental conditions and verifies that the foundation design meets a specific target reliability level. A 3D finite-element (FE) model is used to predict the long-term response of the SSI, accounting for the accumulation of permanent cyclic strain experienced by the soil. The proposed framework was employed for the design of a large-diameter monopile supporting a 10 MW offshore wind turbine.

scholarly journals Reliability analysis of offshore wind turbine foundations under lateral cyclic loading

2019 ◽  
Author(s):  
Gianluca Zorzi ◽  
Amol Mankar ◽  
Joey Velarde ◽  
John D. Sørensen ◽  
Patrick Arnold ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Wind Turbine ◽  
Limit State ◽  
Large Diameter ◽  
Probabilistic Approach ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Fe Model ◽  
Foundation Design

Abstract. The design of foundations for offshore wind turbines (OWT) requires the assessment of the long-term performance of the soil–structure-interaction (SSI) which is subjected to a large number of cyclic loadings. In terms of serviceability limit state (SLS), it has to be ensured that the foundation does not exceed the operational tolerance prescribed by the wind turbine manufacturer throughout its lifetime. This work aims at developing a probabilistic approach along with a reliability framework with emphasis on verifying the SLS criteria in terms of maximum allowable rotation during an extreme cyclic loading event. This reliability framework allows the quantification of uncertainties in soil properties, in the constitutive soil model for cyclic loadings and extreme environmental conditions and verifies that the foundation design meets a specific target reliability level. A 3D finite element (FE) model is used to predict the long-term response of the SSI accounting for the accumulation of permanent cyclic strain experienced by the soil. The proposed framework is employed for the design of a large diameter monopile supporting a 10 MW offshore wind turbine.

scholarly journals Physical Modelling of Offshore Wind Turbine Foundations for TRL (Technology Readiness Level) Studies

2021 ◽  
Vol 9 (6) ◽  
pp. 589
Author(s):  
Subhamoy Bhattacharya ◽  
Domenico Lombardi ◽  
Sadra Amani ◽  
Muhammad Aleem ◽  
Ganga Prakhya ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Prior Experience ◽  
Physical Modelling ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Foundation Design ◽  
Offshore Wind Turbines ◽  
Sea Bed ◽  
Geological Conditions

Offshore wind turbines are a complex, dynamically sensitive structure due to their irregular mass and stiffness distribution, and complexity of the loading conditions they need to withstand. There are other challenges in particular locations such as typhoons, hurricanes, earthquakes, sea-bed currents, and tsunami. Because offshore wind turbines have stringent Serviceability Limit State (SLS) requirements and need to be installed in variable and often complex ground conditions, their foundation design is challenging. Foundation design must be robust due to the enormous cost of retrofitting in a challenging environment should any problem occur during the design lifetime. Traditionally, engineers use conventional types of foundation systems, such as shallow gravity-based foundations (GBF), suction caissons, or slender piles or monopiles, based on prior experience with designing such foundations for the oil and gas industry. For offshore wind turbines, however, new types of foundations are being considered for which neither prior experience nor guidelines exist. One of the major challenges is to develop a method to de-risk the life cycle of offshore wind turbines in diverse metocean and geological conditions. The paper, therefore, has the following aims: (a) provide an overview of the complexities and the common SLS performance requirements for offshore wind turbine; (b) discuss the use of physical modelling for verification and validation of innovative design concepts, taking into account all possible angles to de-risk the project; and (c) provide examples of applications in scaled model tests.

Permanent accumulated rotation of offshore wind turbine monopile due to typhoon-induced cyclic loading

2021 ◽  
Vol 80 ◽  
pp. 103079
Author(s):  
Hongwang Ma ◽  
Zhiyue Lu ◽  
Yutao Li ◽  
Chen Chen ◽  
Jun Yang
Keyword(s):  
Cyclic Loading ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Offshore Wind Turbine

Long-Term Dynamic Monitoring of an Offshore Wind Turbine

2013 ◽  
pp. 253-267 ◽  
Author(s):  
Christof Devriendt ◽  
Filipe Magalhães ◽  
Mahmoud El Kafafy ◽  
Gert De Sitter ◽  
Álvaro Cunha ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Dynamic Monitoring ◽  
Offshore Wind Turbine

scholarly journals A Review of Recent Advancements in Offshore Wind Turbine Technology

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 579
Author(s):  
Taimoor Asim ◽  
Sheikh Zahidul Islam ◽  
Arman Hemmati ◽  
Muhammad Saif Ullah Khalid
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Offshore Wind ◽  
System Level ◽  
Offshore Wind Turbine ◽  
Component Level ◽  
Foundation Design ◽  
Offshore Wind Turbines

Offshore wind turbines are becoming increasingly popular due to their higher wind energy harnessing capabilities and lower visual pollution. Researchers around the globe have been reporting significant scientific advancements in offshore wind turbines technology, addressing key issues, such as aerodynamic characteristics of turbine blades, dynamic response of the turbine, structural integrity of the turbine foundation, design of the mooring cables, ground scouring and cost modelling for commercial viability. These investigations range from component-level design and analysis to system-level response and optimization using a multitude of analytical, empirical and numerical techniques. With such wide-ranging studies available in the public domain, there is a need to carry out an extensive yet critical literature review on the recent advancements in offshore wind turbine technology. Offshore wind turbine blades’ aerodynamics and the structural integrity of offshore wind turbines are of particular importance, which can lead towards system’s optimal design and operation, leading to reduced maintenance costs. Thus, in this study, our focus is to highlight key knowledge gaps in the scientific investigations on offshore wind turbines’ aerodynamic and structural response. It is envisaged that this study will pave the way for future concentrated efforts in better understanding the complex behavior of these machines.

On the Modeling of Nonlinear Waves for Prediction of Long-Term Offshore Wind Turbine Loads

2008 ◽  
Author(s):  
P. Agarwal ◽  
L. Manuel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Return Period ◽  
Wave Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Irregular Wave ◽  
Inflow Turbulence

In the design of wind turbines—onshore or offshore—the prediction of extreme loads associated with a target return period requires statistical extrapolation from available loads data. The data required for such extrapolation are obtained by stochastic time-domain simulation of the inflow turbulence, the incident waves, and the turbine response. Prediction of accurate loads depends on assumptions made in the simulation models employed. While for the wind, inflow turbulence models are relatively well established, for wave input, the current practice is to model irregular (random) waves using a linear wave theory. Such a wave model does not adequately represent waves in shallow waters where most offshore wind turbines are being sited. As an alternative to this less realistic wave model, the present study investigates the use of irregular nonlinear (second-order) waves for estimating loads on an offshore wind turbine, with a focus on the fore-aft tower bending moment at the mudline. We use a 5MW utility-scale wind turbine model for the simulations. Using, first, simpler linear irregular wave modeling assumptions, we establish long-term loads and identify governing environmental conditions (i.e., the wind speed and wave height) that are associated with the 20-year return period load derived using the inverse first-order reliability method. We present the nonlinear irregular wave model next and incorporate it into an integrated wind-wave-response simulation analysis program for offshore wind turbines. We compute turbine loads for the governing environmental conditions identified with the linear model and also for an extreme environmental state. We show that computed loads are generally larger with the nonlinear wave modeling assumptions; this establishes the importance of using such refined nonlinear wave models in stochastic simulation of the response of offshore wind turbines.

scholarly journals Reliability-Based Serviceability Limit State Design of a Jacket Substructure for an Offshore Wind Turbine

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2751 ◽  
Author(s):  
Jianhua Zhang ◽  
Won-Hee Kang ◽  
Ke Sun ◽  
Fushun Liu
Keyword(s):  
Correlation Analysis ◽  
Reliability Analysis ◽  
Limit State ◽  
Statistical Correlation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
State Function ◽  
Optimized Design ◽  
Foundation Design ◽  
Serviceability Limit State

The development of a structurally optimized foundation design has become one of the main research objectives for offshore wind turbines (OWTs). The design process should be carried out in a probabilistic way due to the uncertainties involved, such as using parametric uncertainties regarding material and geometric properties, and model uncertainties in resistance prediction models and regarding environmental loads. Traditional simple deterministic checking procedures do not guarantee an optimized design because the associated uncertainties are not fully considered. In this paper, a reliability analysis framework is proposed to support the optimized design of jacket foundations for OWTs. The reliability analysis mainly considers the serviceability limit state of the structure according to the requirements of the code. The framework consists of two parts: (i) an important parameter identification procedure based on statistical correlation analysis and (ii) a finite element-simulation-based reliability estimation procedure. The procedure is demonstrated through a jacket structure design of a 3 MW OWT. The analysis results show that the statistical correlation analysis can help to identify the parameters necessary for the overall structural performance. The Latin hypercube sampling and the Monte Carlo simulation using FE models effectively and efficiently evaluate the reliability of the structure while not relying on a surrogate limit state function. A comparison between the proposed framework and the deterministic design shows that the framework can help to achieve a better result closer to the target reliability level.

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