Reliability analysis of mooring lines using copulas to model statistical dependence of environmental variables

Montes-Iturrizaga, R.; Heredia‐Zavoni, Ernesto

doi:10.1016/j.apor.2016.07.008

Cited by 28 publications

(21 citation statements)

References 19 publications

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“…Note that the order of magnitude of P f may change depending on the value of α. The probabilities from Reference [21], are alarming when compared with typical values found for other offshore systems, for example, References [41,42]. This is also indicative on the very conservative perspective inherent to this approach, when compared with the optimized approach from Reference [5].…”

Section: Statically Stable Scour Protectionsmentioning

confidence: 76%

“…The present work showed that reliability methodologies can provide useful insights on the safety associated to the several design choices and criteria adopted for scour protections. Moreover, a contribution is made on highlighting knowledge gaps, namely the definition of the acceptable probability of failure and the influence of the failure criteria, that need further assessment to move the reliability based design of scour protections towards the same mature level as in other fields of offshore engineering, for example, References [41,42,49]. Funding: This work is supported by the project POCI-01-0145-FEDER-032170 (ORACLE project), funded by the European Fund for Regional Development (FEDER), through the COMPETE2020, the Programa Operacional Competitividade e Internacionalização (POCI) and FCT/MCTES through national funds (PIDDAC).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Probabilistic Comparison of Static and Dynamic Failure Criteria of Scour Protections

Fazeres-Ferradosa

Taveira-Pinto

Rosa-Santos

et al. 2019

JMSE

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The present paper provides a reliability assessment of scour protections applicable to both the static and dynamic stability design. As a case study, Horns Rev 3 hindcast data is used to simulate different failure criteria for an exemplary scour protection suitable for an offshore monopile foundation. The results show that the probability of failure is influenced by several factors, namely the wave friction factor, the definition of the acceptable damage number or the formulations used to calculate the bed shear-stress. The reliability assessment also indicates that annual probabilities of failure, associated to each criterion, might be comparable with the values presented in reliability standards for marine structures. Based on the results, this paper highlights future recommendations to improve the reliability-based design and analysis of scour protections for offshore foundations.

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Section: Statically Stable Scour Protectionsmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Probabilistic Comparison of Static and Dynamic Failure Criteria of Scour Protections

Fazeres-Ferradosa

Taveira-Pinto

Rosa-Santos

et al. 2019

JMSE

View full text Add to dashboard Cite

show abstract

“…There are several studies in the literature that have considered the reliability assessment of various anchor families such as suction anchors (Choi, 2007;Valle-molina et al, 2008;Clukey et al, 2013;Silva-González et al, 2013;Montes-Iturrizaga and Heredia-Zavoni, 2016;Rendón-Conde and Heredia-Zavoni, 2016). The high level of certainties in the evaluation of the holding capacity of suction anchors and the promising results obtained in aforementioned reliability studies has provided confidence about no need for field trials in assessment of holding capacities of these anchors.…”

Section: Introductionmentioning

confidence: 99%

Reliability assessment of drag embedment anchors in sand and the effect of idealized anchor geometry

Aslkhalili

Shiri

Zendehboudi

2019

Saf. Extreme Environ.

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In this study, the reliability of drag embedment anchors in the sand was assessed and the effect of anchor geometrical idealization on reliability indices was investigated as an inherited characteristic of analytical approaches. The anchor holding capacity was obtained by performing a series of iterative limit state analyses and a probabilistic model was developed for the selected anchor families. The tensions of the mooring lines connected to a semisubmersible platform were obtained by performing a series of time-domain dynamic mooring analyses using the OrcaFlex software. The uncertainties in environmental loads, metocean variables, and stress distribution along the catenary mooring lines were incorporated into the line tensions through the response surfaces. An iterative procedure was performed by adopting the first-order reliability method (FORM) to calculate the comparative failure probabilities in sand and clay. The study showed significant dependence of the anchoring system reliability on geometrical configuration of anchors, the seabed soil properties, and the environmental loads. It was observed that the implementation of the reliability-based design into the existing in-filed trial procedures could significantly improve the efficiency and cost-effectiveness of the design practice.

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“…However, the joint modelling of the significant wave height and the mean up-crossing period, or eventually the peak period, enables a more precise description of the sea-state and it is fundamental for several aspects of design, e.g. in the fatigue limit state assessment [9], the scour phenomena at the foundation [10] or the reliability of structural elements as the mooring lines [11].…”

Section: Introductionmentioning

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 analysis of mooring lines using copulas to model statistical dependence of environmental variables

Cited by 28 publications

References 19 publications

Probabilistic Comparison of Static and Dynamic Failure Criteria of Scour Protections

Probabilistic Comparison of Static and Dynamic Failure Criteria of Scour Protections

Reliability assessment of drag embedment anchors in sand and the effect of idealized anchor geometry

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

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