Alleviation of Fatigue in Renewable Energy Support Structures

2011 ◽  
Author(s):  
Feargal Brennan
Keyword(s):  
Renewable Energy ◽  
Offshore Structures ◽  
Support Structures ◽  
Design Standards ◽  
New Era ◽  
The North ◽  
Current Design ◽  
1960S And 1970S ◽  
The 1960S ◽  
Stress Fatigue

Offshore renewable energy is experiencing an explosion of activity in response to ambitious renewable energy targets, however the drive to increase turbine size in deeper water whilst at the same time to reduce capex and installation costs in addition to the speed of development means there is a danger that structures may be designed and deployed that are inherently prone to fatigue. Offshore structures have come a long way since the pioneering early Oil & Gas jackets in the 1960s and 1970s. In forty years of designing and operating large Oil & Gas structures in the North Sea tremendous changes have occurred in development of advanced numerical modelling of stress, fatigue and loading in addition to vast improvements in steel quality/strength, manufacturing processes and inspection, monitoring and quality control. This paper addresses some of the fundamental areas where current design standards may not be appropriate for renewable energy support structures in this new era of advanced sensors and information systems. It will also discuss advanced fatigue alleviation techniques.

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.

Contested Colonialism: Responsible Government and Political Development in Yukon

2014 ◽  
Vol 47 (2) ◽  
pp. 375-396 ◽  
Author(s):  
Jerald Sabin
Keyword(s):  
Indigenous Peoples ◽  
Political Development ◽  
Political Movement ◽  
Political Behaviour ◽  
The North ◽  
Critical Junctures ◽  
Responsible Government ◽  
1960S And 1970S ◽  
Colonial Order ◽  
The 1960S

AbstractThis article argues that the granting of responsible government to Yukon in 1979 was not the inevitable outcome of territorial political development but the result of a protracted and organized settler political movement that emerged first in opposition to the federal government and, later, to Yukon's Indigenous peoples. I analyze settler actor political behaviour and outcomes using the framework of “contested colonialism.” Non-Indigenous Yukoners are understood as actors who simultaneously bring colonialism to the North while also contesting elements of that same colonial order. Using extensive archival research, I identify several critical junctures leading to the implementation of responsible government during the 1960s and 1970s.

IS INTERNATIONAL LAW IMPARTIAL?

Legal Theory ◽  
2005 ◽  
Vol 11 (1) ◽  
pp. 39-74 ◽  
Author(s):  
Steven R. Ratner
Keyword(s):  
Vietnam War ◽  
Just War Theory ◽  
Law Of Peoples ◽  
The North ◽  
Permissible Range ◽  
Disparate Treatment ◽  
1960S And 1970S ◽  
The 1960S ◽  
Core Questions ◽  
Ethical Significance

The last decade has seen a resurgence of interest among philosophers in the core questions of ethics and justice on the international plane. Issues once discussed primarily in the response to the major global debates of the 1960s and 1970s—the Vietnam War and the North-South economic imbalance—have returned to the domain of philosophers. This engagement has taken place in two distinct but related debates. First, philosophers have devoted attention to the ethical significance of nationality and patriotism, asking whether an impartial morality permits disparate treatment of an individual's co-nationals. Second, scholars have revisited issues of international justice in great detail, including works on human rights as well as just war theory. These works ask, as Brian Barry put it, “given a world that is made up of states, what is the morally permissible range of diversity among them?” One impetus for renewed work on these ideas was the publication of John Rawls's The Law of Peoples.

scholarly journals Covid Conversations 3: Elizabeth LeCompte and Kate Valk

2021 ◽  
Vol 37 (3) ◽  
pp. 205-222
Author(s):  
Elizabeth LeCompte ◽  
Kate Valk ◽  
Maria Shevtsova
Keyword(s):  
New York ◽  
Small Scale ◽  
Wooster Group ◽  
Avant Garde ◽  
American System ◽  
The North ◽  
Main Work ◽  
Stage Direction ◽  
1960S And 1970S ◽  
The 1960S

Elizabeth LeCompte co-founded The Wooster Group with like-minded pioneers in New York in 1975, leading and directing its collaborators as deaths, departures, and new arrivals have changed its composition and emphases over the decades, segueing into a world-wide uncertain present. Kate Valk joined in 1978, the last representative of The Wooster Group’s foundational period, apart from LeCompte herself, who is still a key member of the company. References in this conversation are primarily to works after 2016. LeCompte briefly remarks on the importance of Since I Can Remember – one of the Group’s ongoing works in progress in 2021 – as an archival project that draws on Valk’s memory of how Nayatt School was made during her formative years. Having become, since then, a quintessential Wooster Group performer, Valk extended her artistic skills to stage direction, undertaking, most recently, The B-Side (2017). Both the initiative and idea for the piece came from performer Eric Berryman, who had brought Valk the collection of blues, songs, spirituals, and preachings on the 1965 LP made from the research of scholar folklorist Bruce Chapman. Berryman had been inspired to approach Valk because of her exclusive use of unadulterated historical recordings in Early Shaker Spirituals (2014), her directorial debut. The main work in rehearsal during 2020 and which was still locked down by the Covid-19 pandemic at the time of this conversation is The Mother, a Wooster Group variant of Brecht’s dramatized version of Gorky’s novel, directed by LeCompte. LeCompte discusses the current situation, emphasizing the increased vulnerability of independent artists and small-scale theatre, while giving a glimpse of the disadvantages for such groupings built into the North American system of project funding. The Wooster Group is a salient example of small-scale theatre that, despite continually precarious conditions, which the pandemic has highlighted and exacerbated, has achieved its creative goals and has defined its place in the exploratory avant-garde flourishing vigorously in the 1960s and 1970s. This particular avant-garde, LeCompte believes, has seen various important developments over the years but might well now be counting its last days. The conversation here presented was recorded on 31 October 2020, transcribed by Kunsang Kelden, and edited by Maria Shevtsova, Editor of New Theatre Quarterly.

scholarly journals Geological observations in the southern West Greenland basement from Ameralik to Frederikshåb Isblink in 2008

1969 ◽  
Vol 17 ◽  
pp. 49-52
Author(s):  
Nynke Keulen ◽  
Anders Scherstén ◽  
John C. Schumacher ◽  
Tomas Næraa ◽  
Brian F. Windley
Keyword(s):  
Mineral Exploration ◽  
Basic Research ◽  
Field Work ◽  
Digital Map ◽  
West Greenland ◽  
The North ◽  
Recent Developments ◽  
1960S And 1970S ◽  
The 1960S ◽  
Terrane Accretion

In 2008, the Geological Survey of Denmark and Greenland began a project in collaboration with the Bureau of Minerals and Petroleum of Greenland with the aim to publish a webbased, seamless digital map of the Precambrian bedrock between 61°30´ and 64°N in southern West Greenland. Such a map will be helpful for the mineral exploration industry and for basic research. Producing an updated digital map requires additional field work revisiting key localities to collect samples for geochemistry, geochronology and metamorphic petrology. The new data will help us to test and refine existing models and improve general understanding of the geological evolution of the area. Here we summarise some results from the 2008 field activities between Ame - ralik in the north and Frederikshåb Is - blink in the south (Fig. 1). The area was mapped in the 1960s and 1970s, and although the 1:100 000-scale maps are of excellent quality, they do not include more recent developments in geochro - nology, thermobarometry and geochemistry. A notable exception is the Fiske - næsset complex (Fig. 1), which has re ceived considerable attention after it was first mapped (Ellitsgaard-Ras - mus sen & Mouritzen 1954; Wind ley et al., 1973; Windley & Smith, 1974; Myers 1985). New tectonic models have been developed since the original 1:100 000 maps were produced, and the tectonic evolution has been com - monly ex plained in terms of terrane accretion (Friend et al. 1996).

scholarly journals An Anatomy of the Cooling of the North Atlantic Ocean in the 1960s and 1970s

2014 ◽  
Vol 27 (21) ◽  
pp. 8229-8243 ◽  
Author(s):  
Daniel L. R. Hodson ◽  
Jon I. Robson ◽  
Rowan T. Sutton
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Meridional Overturning Circulation ◽  
Subpolar Gyre ◽  
Considerable Uncertainty ◽  
The North ◽  
The North Atlantic ◽  
1960S And 1970S ◽  
The 1960S

Abstract In the 1960s and early 1970s, sea surface temperatures in the North Atlantic Ocean cooled rapidly. There is still considerable uncertainty about the causes of this event, although various mechanisms have been proposed. In this observational study, it is demonstrated that the cooling proceeded in several distinct stages. Cool anomalies initially appeared in the mid-1960s in the Nordic Seas and Gulf Stream extension, before spreading to cover most of the subpolar gyre. Subsequently, cool anomalies spread into the tropical North Atlantic before retreating, in the late 1970s, back to the subpolar gyre. There is strong evidence that changes in atmospheric circulation, linked to a southward shift of the Atlantic ITCZ, played an important role in the event, particularly in the period 1972–76. Theories for the cooling event must account for its distinctive space–time evolution. The authors’ analysis suggests that the most likely drivers were 1) the “Great Salinity Anomaly” of the late 1960s; 2) an earlier warming of the subpolar North Atlantic, which may have led to a slowdown in the Atlantic meridional overturning circulation; and 3) an increase in anthropogenic sulfur dioxide emissions. Determining the relative importance of these factors is a key area for future work.

scholarly journals Catch history of ringed seals (Phoca hispida) in Canada

1998 ◽  
Vol 1 ◽  
pp. 100 ◽  
Author(s):  
Randall R Reeves ◽  
George W Wenzel ◽  
Michael CS Kingsley
Keyword(s):  
Ringed Seal ◽  
Phoca Hispida ◽  
The North ◽  
Cystophora Cristata ◽  
Ringed Seals ◽  
Levels Of Use ◽  
History Of ◽  
European Trade ◽  
1960S And 1970S ◽  
The 1960S

The ringed seal (Phoca hispida) has always been a staple in the diet and household economy of Inuit in Canada. The present paper was prepared at the request of the NAMMCO Scientific Committee to support their assessment of ringed seal stocks in the North Atlantic Basin and adjacent arctic and subarctic waters. Specifically, our objective was to evaluate recent and current levels of use of ringed seals by Canadian Inuit. Annual removals probably were highest (possibly greater than 100,000) in the 1960s and 1970s, a period when sealskin prices were particularly strong. Catches declined substantially in the 1980s following a collapse in sealskin prices, presumably related to the European trade ban on skins from newborn harp and hooded seals (Phoca groenlandica and Cystophora cristata, respectively). Recent catch levels throughout Canada (1980s and early 1990s) are believed to be in the order of 50,000 to 65,000 ringed seals, with a total average annual kill (including hunting loss) in the high tens of thousands. No reliable system is in place to monitor catches of ringed seals, so any estimate must be derived from a heterogeneous array of sources.

scholarly journals Origins of the Kalinowszczyzna district in Lublin: history, design principles and current condition

1970 ◽  
Vol 14 (3) ◽  
pp. 61-70
Author(s):  
Michał Dmitruk
Keyword(s):  
Rural Areas ◽  
Design Principles ◽  
Master Plan ◽  
Administrative Functions ◽  
The North ◽  
1960S And 1970S ◽  
The 1960S ◽  
The City ◽  
Housing Estates

Lublin developed rapidly at the turn of the 1960s and 1970s. Large residential districts were designed on rural areas surrounding the city. Lublin was expanded in almost every geographical direction, in accordance to the principles specified in the 1959 city master plan. The Kalinowszczyzna district was located in the north, covering local hills and ravines, and replacing the former farm and manor it was subsequently named after. The housing estates constructed there were erected mainly by means of prefabricated elements, and included both flats and shops. They also played cultural and administrative functions. The plan’s implementation was launched in 1963 and came to an end in 1980s. Kalinowszczyzna is currently one of 27 administrative districts of Lublin and constitutes an essential part of the city.

An Assessment of Structural Design Guidelines for Offshore Wind Turbines

2007 ◽  
Author(s):  
Rakesh K. Saigal ◽  
Dan Dolan ◽  
Armen Der Kiureghian ◽  
Tim Camp ◽  
Charles E. Smith
Keyword(s):  
Renewable Energy ◽  
Wind Turbine ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Guidance Document ◽  
Support Structures ◽  
Design Standards ◽  
Offshore Wind Farms ◽  
Design Requirements

This paper addresses the need for U.S. standards to establish design requirements for offshore wind turbine support structures. There are wind power resources in U.S. waters that can be developed to generate substantial amounts of clean, renewable energy. While a number of offshore wind farms have been proposed for U.S. waters none have been built. The U.S. Minerals Management Service and the National Renewable Energy Laboratory have recently commissioned a study to compare and benchmark the International Electrotechnical Commission (IEC) design standards with the American Petroleum Institute (API) recommended practices. Offshore wind farms that are operating in Europe have been designed using standards developed specifically for offshore wind, such as those developed by Germanischer Lloyd (GL) and Det Norske Veritas (DNV). The IEC has recently drafted design requirements specifically for offshore wind farms that provides a comprehensive definition of load conditions and references other standards, where needed, to provide a complete guidance document. The intent of this paper is to examine the range of applicability of the various design standards and to assess how these standards apply to the design of U.S. offshore wind turbine (OWT) support structures.

Cold-formed steel battened built-up columns: Experimental behaviour and verification of different design rules developed

2021 ◽  
pp. 136943322110480
Author(s):  
A.R. Dar ◽  
S. Vijayanand ◽  
M. Anbarasu ◽  
M. Adil Dar
Keyword(s):  
Failure Modes ◽  
Numerical Models ◽  
Experimental Studies ◽  
Design Standards ◽  
Uniform Compression ◽  
Design Rules ◽  
The North ◽  
Current Design ◽  
Cold Formed Steel ◽  
In The Beginning

Some of the past studies on cold-formed steel (CFS) battened built-up columns have resulted in the development of new design rules for predicting their axial strengths. However, the main drawbacks of such studies are that they are purely numerical and the numerical models developed for such parametric studies were validated using the test results on similar built-up column configurations, but not the exact ones. Therefore, experimental studies on CFS battened columns comprising of lipped channels are needed for verifying the accuracy of the proposed design rules for CFS battened columns. This paper reports an experimental study performed on CFS built-up battened columns under axial compression. Adequately spaced identical lipped channels in the back-to-back arrangement were used as chords and were connected by batten plates laterally with self-driving screws to form the built-up members. The dimensions of chords were fixed as per the geometric limits given out in the North American Specifications (NAS) for the design of CFS structural members. The sectional compactness of the chords and the overall slenderness of the built-up columns were varied by altering the thickness of the channels and height of the built-up columns, respectively. A total of 20 built-up sections were tested under uniform compression to investigate the behavioural changes in the built-up columns due to these variations. The behaviour assessment was made in terms of peak strengths, load–displacement response and failure modes of the test specimens. The current design standards on CFS structures were used to determine the design strengths and were compared against the test strengths for assessing their adequacy. Furthermore, as discussed in the beginning, the test strengths were used to verify the accuracy of the different relevant proposed design rules in the literature.

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