Fixed and jack-up platforms: Basis for reliability assessment

Frieze, P A; Morandi, Alberto; Birkinshaw, M.; Smith, D.J.; Dixon, A.T.

doi:10.1016/s0951-8339(97)00001-4

Cited by 13 publications

(9 citation statements)

References 15 publications

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“…...... (13) where 0 V ′ is a dummy variable which is adjusted so that the potential passes through the current load point. h α and m α are non-dimensional association factors relating the shape of the plastic potential to that of the yield surface.…”

Section: Expeiinrentnl Evidence On Flat Platesmentioning

confidence: 99%

On the Modelling of Foundations for Jack-up Units on Sand

Cassidy

Houlsby

1999

All Days

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There is a steadily increasing demand for the use of jack-up units in deeper water and harsher environments. To be confident of their use in these environments there is a need for jack-up analysis techniques to reflect accurately the physical processes occurring. The common modelling of spudcan footings as pinned or as linear springs is an over-simplification of foundation behaviour, and can therefore lead to overconservative design. This paper details the implementation of a work hardening plasticity model for spudcan footings on dense sand (named Model C) into a dynamic structural analysis program (named JAKUP). The motivation for this is to have a balanced approach to the analysis of jack-up units, with the non-linearities in the structural, foundation and wave loading models all taken into account. Wave loading is considered using NewWave theory, and the importance of random wave histories shown by constraining the deterministic NewWave into a completely random surface elevation. Examples are shown to emphasize the differences in predicted extreme response according to the various footing assumptions: pinned, linear springs and Model C. The role of plasticity theory for modelling foundations will be highlighted. Further uses of JAKUP in the understanding of the extreme response statistics and reliability of jack-up platforms are discussed. This paper is directed to those interested in the long-term reliability analysis of jack-up units.

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Section: Expeiinrentnl Evidence On Flat Platesmentioning

confidence: 99%

On the Modelling of Foundations for Jack-up Units on Sand

Cassidy

Houlsby

1999

All Days

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“…In addition, the computation time increases for small probability of failures (Veritas 1992). Frieze et al (1997) mentioned that Monte Carlo simulation produces noisy approximation of probability which becomes difficult to use for gradient-based optimisation compared with FORM. For cases of large number of random variables or for a very low probability of failure magnitude, the analysis requires large number of sampling sets, thus increases the computational time and effort (Kolios 2010).…”

Section: Structural Reliability Analysismentioning

confidence: 99%

Condition Assessment Techniques for Aged Fixed-Type Offshore Platforms Considering Decommissioning: a Historical Review

Wahab

Kurian

Liew

et al. 2020

J. Marine. Sci. Appl.

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In this study, the technical papers on structural condition assessment of aged fixed-type offshore platforms reported over the past few decades are presented. Other ancillary related works are also discussed. Large numbers of researches are available in the area of requalification for life extension of offshore jacket platforms. Many of these studies involve reassessment of existing platforms by means of conducting pushover analysis, a static nonlinear collapse analysis method to evaluate the structure nonlinear behaviour and capacity beyond the elastic limit. From here, the failure mechanism and inherent reserve strength/capacity of the overall truss structure are determined. This method of doing reassessment is described clearly in the industry-adopted codes and standards such the API, ISO, PTS and NORSOK codes. This may help understand the structural behaviour of aged fixed offshore jacket structures for maintenance or decommissioning.

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“…The reliability analysis is significantly dependent on and is very susceptible to uncertainty modelling (Marley et al, 2001). Studies on material uncertainty have been made by many authors (Moses and Stahl, 2000;Moses, 1995;Frieze et al, 1997aFrieze et al, ,1997bHess et al, 2002;Duan et al, 2005;BOMEL(a), 2003).…”

Section: Regionmentioning

confidence: 99%

“…This can be represented by stochastic processes or random variables. Different methods for finding the response of offshore Jackets, subjected to random ocean forces have been widely published (Birades et al, 2003;Moses, 1995;Frieze et al, 1997aFrieze et al, ,1997bRenolds et al, 2007;Stahl et al, 1998). The method adopted in this study for component and joint reliability index is based on the SHELL method used for development of load factors for ISO 19902 as shown in Eq.…”

Section: Environmental Load Modellingmentioning

confidence: 99%