Generic framework for reliability assessment of offshore wind turbine jacket support structures under stochastic and time dependent variables

Ivanhoe, R.O.; Wang, Lin; Kolios, Athanasios

doi:10.1016/j.oceaneng.2020.107691

Cited by 26 publications

(13 citation statements)

References 31 publications

(28 reference statements)

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“…Applications of the T-D SRA for the design of modern metal structures such as those deployed offshore (i.e., in environments characterized by highly stochastic loads and resistance properties, thus necessitating the need for SRA to account for such uncertainties systematically) include [2,3,44,[47][48][49][89][90][91][92][93][94]. In [95], the fatigue reliability of fixed offshore platforms was investigated by analyzing different failure scenarios.…”

Section: Critical Discussionmentioning

confidence: 99%

“…This approach is particularly useful as it enables enhanced analysis of elements under a stochastic perspective, accounting for design uncertainties efficiently [46]. In [2,3,[47][48][49], the efficiency of the SRSM for advanced RA of Offshore Wind Turbine (OWT) jacket support structures was demonstrated. According to the authors, a parametric FEA model was developed, and then stochastic FEA simulations were performed.…”

Section: Response Surface Methodsmentioning

confidence: 99%

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A Systematic Review of Structural Reliability Methods for Deformation and Fatigue Analysis of Offshore Jacket Structures

Shittu

Kolios

Mehmanparast

2020

Metals

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This paper presents the state of the art in Structural Reliability Analysis (SRA) methods with a view of identifying key applications of each method and its proposed variations, qualifying characteristics, advantages, and limitations. Due to the increasing complexity and scale of modern offshore jacket structures, it becomes increasingly necessary to propose an accurate and efficient approach for the assessment of uncertainties in their material properties, geometric dimensions, and operating environments. SRA, as a form of uncertainty analysis, has been demonstrated to be a useful tool in the design of structures because it can directly quantify how uncertainty about input parameters can affect structural performance. Herein, attention was focused specifically on the probabilistic fracture mechanics approach because this accounts accurately for fatigue reliability mostly encountered as being dominant in the design of such structures. The well-established analytical/approximate methods such as the First- and Second-Order Reliability Methods (FORM/SORM) are widely used as they offer a good balance between accuracy and efficiency for realistic problems. They are, however, inaccurate in cases of highly non-linear systems. As a result, they have been modified using methods such as conjugate search direction approach, saddle point approximation, subset simulation, evidence theory, etc. in order to improve accuracy. Initially, direct simulations methods such as the Monte Carlo Simulation Method (MCS) with its various variance reduction techniques such as the Importance Sampling (IS), Latin Hypercube Sampling (LHS), etc. are ideal for structures having non-linear limit states but perform poorly for problems that calculate very low probabilities of failure. Overall, each method has its own merits and limitation, with FORM/SORM being the most commonly used, but recently, simulation methods have increasingly been used due to continuous advances in computation powers. Other relevant methods include the Response Surface Methods (RSM) and the Surrogate Models/Meta-models (SM/MM), which are advanced approximation methods and are ideal for structures with implicit limit state functions and high-reliability indices. Combinations of advanced approximation methods and reliability analysis methods are also found in literature as they can be suitable for complex, highly non-linear problems.

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Section: Critical Discussionmentioning

confidence: 99%

Section: Response Surface Methodsmentioning

confidence: 99%

A Systematic Review of Structural Reliability Methods for Deformation and Fatigue Analysis of Offshore Jacket Structures

Shittu

Kolios

Mehmanparast

2020

Metals

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“…Here, the mean values of wave and current parameters in 50-year return period are referenced in [17]. The loads from wind turbines and wave and current parameters are assumed to follow normal distribution with standard deviation equal to 10% of their mean values as done in [26]. As for the thickness parameters T grey and T blue , they represents respectively the thickness of braces in splash zone with grey color and the thickness of legs in splash zone with blue color as showed in Fig.2.…”

Section: Parameter Selectionmentioning

confidence: 99%

Structural Reliability Assessment of Offshore Wind Turbine Jacket Considering Corrosion Degradation

Ren¹,

Aoues²,

Lemosse³

et al. 2021

14th WCCM-ECCOMAS Congress

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In this paper, an approach is proposed to conduct reliability analysis on an offshore jacket considering corrosion degradation under extreme load cases. Corrosion degradation is considered as thickness wastage of the jacket element, which is seen as time-dependent variables. One probabilistic corrosion in literature is adopted by using different distribution models. Also, three different inspection cases (environmental conditions) of the corrosion are studied. The reliability assessment is evaluated by Crude Monte Carlo simulation based on the trained surrogate model. Deep neural networks are used to train the surrogate model, because they are not limited by the distribution and dimension of variables. The results show that using different corrosion distribution model, the probabilities of failure of the jacket are different, even though they have the same mean and standard deviation values. In addition, with same assumption of the distribution model in corrosion, the reliability of the jacket changes a lot concerning different inspection cases. Furthermore, it is noted that the inspection cases have more influences on the reliability analysis of jacket than different corrosion distribution assumptions. At the end, two recommendations are derived from this work.

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“…where D p is the cylinder diameter, ρ water = 1025 kg/m 3 is the density of water, Ů(z,t) is the acceleration of water [72], U(z, t) = U wave (z, t) + U current is the velocity of the fluid, and U current = 1 m/s is the current speed which is considered constant in this study. Finally, C m = 2 is the inertial coefficient and C d = 1 is the drag coefficient: these values are deterministic values [71,73].…”

Section: Hydrodynamic Loadsmentioning

confidence: 99%

Analysing the Influential Parameters on the Monopile Foundation of an Offshore Wind Turbine

et al. 2021

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Countries around the world generate electricity from renewable resources to decarbonise their societies and reduce global warming. Some countries have already outlined their wishes to produce a part of their total energy consumption from renewable sources in the coming years and gradually reduce the use of nuclear energy and fossil fuel in favour of cleaner fuels. While renewable energies are significant factors in tackling climate change, the parameters that can influence their performance should be analysed in detail during the design process. One of these parameters is the foundation of an offshore wind turbine. Offshore wind turbines allow more energy to be produced than an onshore installation, and do not have any harmful effects on human beings, while their geotechnical aspects need to be clearly determined in advance. In this study, the influential parameters such as soil type, the number of bolts in the design, and the size of the structure were analysed using the finite element method for three different designs. The simulations showed that some soil properties, such as cohesion, do not influence the results, while Young’s modulus has a large influence on the designs. Additionally, the results of this study showed that the maximum stress concentrations are at the bolts and connection joints where they are too close to the steel’s yield stress. It also proves that the non-elastic behaviour of the soil does not require to be assigned for such analyses and it can be simplified only with its elastic behaviour. The embedded length affects the lateral displacement, while the number of bolts influences the structure’s resistance to external loads.

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Generic framework for reliability assessment of offshore wind turbine jacket support structures under stochastic and time dependent variables

Cited by 26 publications

References 31 publications

A Systematic Review of Structural Reliability Methods for Deformation and Fatigue Analysis of Offshore Jacket Structures

A Systematic Review of Structural Reliability Methods for Deformation and Fatigue Analysis of Offshore Jacket Structures

Structural Reliability Assessment of Offshore Wind Turbine Jacket Considering Corrosion Degradation

Analysing the Influential Parameters on the Monopile Foundation of an Offshore Wind Turbine

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