scholarly journals Reliability Updating of Offshore Structures Subjected to Marine Growth

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 414
Author(s):  
Franck Schoefs ◽  
Thanh-Binh Tran
Keyword(s):  
Limit State ◽  
Dynamic Bayesian Network ◽  
Offshore Structures ◽  
Drag Forces ◽  
The North ◽  
The North Sea ◽  
Inspection And Maintenance ◽  
Inspection Data ◽  
Atlantic Area

Marine growth is a known problem for oceanic infrastructure and has been shown to negatively impact the reliability of bottom-fixed or floating offshore structures submitted to fatigue or extreme loading. Among other effects, it has been shown to change drag forces by increasing member diameters and modifying the roughness. Bio-colonization being highly random, the objective of this paper is to show how one-site inspection data increases reliability by decreasing uncertainties. This can be introduced in a reliability-based inspection framework for optimizing inspection and maintenance (here, cleaning). The modeling and computation are illustrated through the reliability analysis of a monopile in the European Atlantic area subjected to marine growth and according to the plastic collapse limit state. Based on surveys of structures in the North Sea, long-term stochastic modeling (space and time) of the marine growth thickness is first suggested. A Dynamic Bayesian Network is then developed for reliability updating from the inspection data. Finally, several realistic (10–20 measurements) inspection strategies are compared in terms of reliability improvement and the accuracy of reliability assessment.

Development of Fatigue Design Standards for Marine Structures

2017 ◽  
Author(s):  
Inge Lotsberg
Keyword(s):  
North Sea ◽  
Wind Turbines ◽  
Offshore Structures ◽  
Support Structures ◽  
Marine Structures ◽  
Design Standards ◽  
The North ◽  
Fatigue Design ◽  
The North Sea

Fatigue design standards for offshore structures became needed with development of offshore structures in harsh environments like the North Sea during the 1970s. The Ultimate Limit State had earlier been the most significant design requirement for similar platforms in the Mexican Gulf being less utilized with respect fatigue. The need for fatigue design of ship structures became increased as more high strength steel was being used in these structures during the 1970s. The analysis method for long term loading and assessment of fatigue capacity has been improved over the years and this has also resulted in need for new and revised design standards. New types of structures and structural components have been developed like tension leg platforms and support structures for wind turbines. These structures are subjected to significant dynamic loading such that fatigue design becomes the main issue and relevant fatigue design standards are needed. Fatigue assessment of fixed offshore structures in the North Sea has been standard practice since the 1970s. Fatigue of floating platforms became a requirement after the accident with the Alexander Kielland platform in 1980. Later new types of structures have been installed in the North Sea such as tension leg platforms and floating production ships where fatigue has been an important part of the design. A further challenge with respect to fatigue came with the development of support structures for wind turbines to be installed in the sea. This paper gives an overview of the development of fatigue design standards for marine structures over the last 40 years. This includes the significance of refined calculation of long term stress range distribution, calculation of hot spot stress, size effect and effect of mean stress effect on fatigue design of ship structures.

Marine fouling

1992 ◽  
Vol 100 ◽  
pp. 169-184 ◽  
Author(s):  
David Sell
Keyword(s):  
North Sea ◽  
Offshore Structures ◽  
Fouling Communities ◽  
Geographical Differences ◽  
The North ◽  
The North Sea ◽  
Fouling Organisms ◽  
Fouling Assemblages

SynopsisA comparison of macrofouling assemblages on offshore structures in the North Sea has revealed some similarity in their general characteristics, with a predominance in climax communities of relatively few species, such as the plumose anemone Metridium senile (L.) and the soft coral Alcyonium digitatum L., covering large proportions of the substratum. Specific geographical differences in community composition, diversity and successional development have been identified, however, and these are discussed in relation to environmental conditions and larval dispersal. In practical terms, the conservation of offshore fouling communities depends upon the fates of structures supporting these assemblages. Since the U.K.'s approach to platform decommissioning could ultimately involve the in situ toppling of structures in sea depths greater than 100 m, there would appear to be little threat to the long-term existence of offshore habitats for deep-water fouling assemblages. Moreover, an abundance of largely uninvestigated habitats for fouling organisms exists on submerged wrecks and other man-made structures. Thus, there appears to be no basis for a conservation requirement in relation to the fouling communities on fixed structures in the North Sea.

scholarly journals Long-term series in ichthyoplankton: sole and sprat at French coast of the North Sea from 1975 to 1994

1998 ◽  
Vol 21 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Daniel Woehrling ◽  
Geneviève Le Fèvre-Lehoërff
Keyword(s):  
North Sea ◽  
The North ◽  
The North Sea

scholarly journals The ‘Yellow Danger’? Global forces and global fears in the North Sea and beyond (1600–1950)

2015 ◽  
Vol 27 (4) ◽  
pp. 743-754
Author(s):  
Matthias van Rossum
Keyword(s):  
Labour Market ◽  
North Sea ◽  
Labour Markets ◽  
Labour Relations ◽  
The North ◽  
15Th Century ◽  
Global Connections ◽  
The North Sea

Since direct shipping routes between Europe and Asia opened up at the end of the 15th century, the growing intercontinental and regional shipping connections resulted in increasing entanglements between European and Asian maritime labour markets. This article analyses the long term development of the connections between European and Asian maritime labour markets and its impact on socio-cultural (and labour) relations through three elements: first, the changing connections between European and Asian maritime labour markets; second, the changing nature of European and Asian maritime labour markets and its influence on the positions of sailors; and third, the changing relations between European and Asian sailors and its effects on the reactions and interactions in a globalising maritime labour market. It explores how these changing global connections shaped encounters between European and Asian sailors on (intercontinental) shipping in and from the North Sea region, and how it affected the positions and reactions of its workers.

scholarly journals Connectivity of larval stages of sedentary marine communities between hard substrates and offshore structures in the North Sea

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Johan van der Molen ◽  
Luz María García-García ◽  
Paul Whomersley ◽  
Alexander Callaway ◽  
Paulette E. Posen ◽  
...  
Keyword(s):  
North Sea ◽  
Offshore Structures ◽  
Marine Communities ◽  
Larval Stages ◽  
The North ◽  
The North Sea ◽  
Hard Substrates

The history and future of the North Sea benthos

1978 ◽  
Vol 76 (1-3) ◽  
pp. 193-200
Author(s):  
P. E. P. Norton
Keyword(s):  
North Sea ◽  
Bottom Type ◽  
The North ◽  
Late Tertiary ◽  
Long Term Changes ◽  
History Of ◽  
The North Sea ◽  
Temperature Depth

SynopsisThis is a brief review intended to supply bases for prediction of future changes in the North Sea Benthos. It surveys long-term changes which are affecting the benthos. Any prediction must take into account change in temperature, depth, bottom type, tidal patterns, current patterns and zoogeography of the sea and the history of these is briefly touched on from late Tertiary times up to the present. From a prediction of changes in the benthos, certain information concerning the pelagic and planktonic biota could also be derived.

scholarly journals DESIGN, ANALYSIS AND FIELD TEST OF A DYNAMIC FLOATING BREAKWATER

1976 ◽  
Vol 1 (15) ◽  
pp. 159 ◽  
Author(s):  
D.J. Agerton ◽  
G.H. Savage ◽  
K.C. Stotz
Keyword(s):  
Solid Wall ◽  
Offshore Structures ◽  
The Past ◽  
The North ◽  
Production Platform ◽  
Floating Breakwater ◽  
The North Sea ◽  
Floating Breakwaters ◽  
Offshore Oil ◽  
Permanent Wave

Interest in floating breakwaters has been generated in recent years because the concept offers the potential of providing a less expensive alternative to traditional, solid wall type barriers for providing permanent wave protection to the thousands of new recreational boat harbors and marinas that have been built in the past 20 years. Also, they may be able to provide temporary, mobile wave protection during construction and installation of offshore facilities for oil transfer and production operations, defense facilities and other offshore structures in deeper water (depths exceeding 50 to 100 feet). The engineering director of one of the largest and most active offshore oil producing companies recently stated that they would be willing to pay up to $6 million for a mobile, floating breakwater that had the proven capability to significantly reduce risks due to wave action during offshore erection in the North Sea or elsewhere. Considering the investment in just one deep water oil production platform already exceeds $100,000,000, the worth of such a reusable, wave protection system during the critical erection period of a platform should be large.

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