Design of scour protections and structural reliability techniques

Fazeres-Ferradosa, Tiago; Taveira-Pinto, Francisco; Neves, Luciana das; Reis, Maria Teresa

doi:10.1201/b21902-91

Cited by 3 publications

(10 citation statements)

References 4 publications

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“…In agreement with the deterministic design previously performed, Figure 6 shows that amplification factors of 3 or 4 leads to very large mean stone diameters, which for a rip-rap scour protection may not be a feasible material to be placed with the fall-pipe vessels, as mentioned by [11].…”

Section: Probabilistic Design Of Scour Protectionssupporting

confidence: 84%

“…Therefore, several works have been performed aiming at optimising the mean stone diameter, e.g. [10], [11] and [12] tried to improve cost-benefit ratios of the scour protection by means of a reduction in the D50. One of the most recent optimisation methods consists in designing a dynamic scour protection, instead of the static one, commonly used in the industry, e.g.…”

Section: Figure 1 Scour Protection With Armour and Filter Layermentioning

confidence: 99%

“…This paper is a contribution to the very few existent studies concerning the maritime environment and the failure of the protection itself, e.g. [11]. Hence, this paper aims to contribute to optimise the design of the protections, under waves and currents combined, by means of failure analysis.…”

Section: Figure 1 Scour Protection With Armour and Filter Layermentioning

confidence: 99%

“…the edge scour phenomenon, which increases for large stone diameters due to the sudden increase of the bed-roughness [44].The results fromTable 2are somehow difficult to compare with other cases in the literature, because there is an evident lack of research performed on the reliability and safety assessment of scour protections analysed by means of the probabilities of failure. A reliability assessment of statically stable scour protections, designed according to[6], is presented by[11]. However, the authors do not consider the correlation effects between the significant wave height and the peak period.…”

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confidence: 99%

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Probabilistic design and reliability analysis of scour protections for offshore windfarms

Fazeres-Ferradosa

Taveira-Pinto

Romão

et al. 2018

Engineering Failure Analysis

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Scour protection is an important component of fixed bottom foundations for offshore wind turbines. Depending on the hydrodynamic conditions, they might be indispensable to avoid the structural collapse of the foundation due to scour phenomena. The design of scour protections is typically deterministic, which often results in overestimated mean diameters of the armour layer. Moreover, the design methodologies currently applied do not provide a measure of safety associated with the proposed design. The present research proposes a novel methodology to assess the safety of the protection and to perform the probabilistic design of static and dynamic scour protections. A case study based on Horns Rev 3 offshore wind farm is used to show how to select the mean stone diameter according to a pre-defined probability of failure of the protection. The results show that a dynamic scour protection could be safely designed with a reduction of the mean stone diameter up to 15 cm, when compared with the statically stable protection.

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Section: Probabilistic Design Of Scour Protectionssupporting

confidence: 84%

Section: Figure 1 Scour Protection With Armour and Filter Layermentioning

confidence: 99%

Section: Figure 1 Scour Protection With Armour and Filter Layermentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Probabilistic design and reliability analysis of scour protections for offshore windfarms

Fazeres-Ferradosa

Taveira-Pinto

Romão

et al. 2018

Engineering Failure Analysis

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“…This type of modelling is not only useful for design purposes but it also yields potential applicability to broader aspects of wind engineering, e.g. to weather prediction for offshore maintenance operations [65], to the estimation of seasonal energy production [66], to the lifetime extension of wind turbines [3] or to scour protections design [60].…”

Section: Discussion and Applications To Wind Engineeringmentioning

confidence: 99%

Asymmetric copula–based distribution models for met-ocean data in offshore wind engineering applications

et al. 2018

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Joint statistical models for long-term wave climate are a key aspect of offshore wind engineering design. However, to find a joint model for sea-state characteristics is often difficult due to the complex nature of the wave climate and the physical constraints of seastate phenomena. The available records of wave heights and periods are often very asymmetric in their nature. This paper presents a copula-based approach to obtain the joint cumulative distribution function of significant wave heights and the mean up-crossing periods. This study is based on 124 months hindcast data concerning Horns Rev 3 offshore wind farm. The extra-parametrization technique of symmetric copulas is implemented to account for the asymmetry present in the data. The analysis of the total sea, the wind-sea and primary swell components is performed separately. The results show that the extraparametrization technique with pairwise copulas consistently provided a better goodnessof-fit when compared to symmetric copulas. Moreover, it is demonstrated that the separation of the total sea into its components does not always improve the extraparametrized copula's performance. Furthermore, this paper also discusses copula application to offshore wind engineering.

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Reliability assessment of offshore dynamic scour protections using copulas

et al. 2018

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This article presents a methodology to assess the reliability of dynamic scour protections used to protect offshore wind turbine foundations. The computed probabilities of failure are based on a dataset of 124 months of hindcast data from the Horns Rev 3 offshore wind farm. Copula-based models are used to obtain the joint distribution function of the significant wave height and spectral peak period and to obtain the probability of failure of scour protections. The sensitivity of the probability of failure to each model is addressed. The influence of the duration of the waves’ time series is also studied. A sensitivity analysis of the probability of failure to physical constraints, such as the water depth, current’s velocity or the mean diameter of the armour units, is performed. The results show that probability of failure is dependent on the copula used to model the spectral parameters and the associated value of Kendall’s τ. It is shown that the copula presenting the best values of Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) did not lead to the probabilities of failure that are closer to the non-parametric estimation, obtained by means of the bivariate version of the Kernel density estimation method. The application to the case study led to annual probabilities of failure, which are comparable with the values applied for other offshore components, according to the current offshore wind industry standards.

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Design of scour protections and structural reliability techniques

Cited by 3 publications

References 4 publications

Probabilistic design and reliability analysis of scour protections for offshore windfarms

Probabilistic design and reliability analysis of scour protections for offshore windfarms

Asymmetric copula–based distribution models for met-ocean data in offshore wind engineering applications

Reliability assessment of offshore dynamic scour protections using copulas

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