Initial Design Phase and Tender Designs of a Jacket Structure Converted into a Retrofitted Offshore Wind Turbine

Abstract

Jackets are the most common structures in the Adriatic Sea for extracting natural gas. These structural typologies are suitable for relative low water depths and flat sandy sea floors. Most of them have been built in the last 50 years. When the underground source finishes, these structures should be moved to another location or removed if they have reached their design life. Nevertheless, another solution might be considered: change the future working life of these platforms by involving renewable energy and transforming them into offshore wind towers. The present research proposal aims to investigate the possibility of converting actual structures for gas extraction into offshore platforms for wind turbine towers. This simplified analysis is useful for initial design phases and tender design, or generally when available information is limited. The model proposed is a new simplified tool used to study the structural analysis of the jacket structure, developed and summarized in 10 steps, firstly adopted to study the behavior of the oil and gas structure and then for the retrofitted wind tower configuration.

Comparative Study of Structural Reliability Assessment Methods for Fixed Offshore Structures

“…Therefore, it might also benefit (re)calibrating partial action and resistance variables in uncommon or exceptional situations. Furthermore, SRA may be valuable for generating comparison data through the earliest design phase [64,65]. As a result, SRA provides a depth of confidence in the ability of a combination of components to perform as assigned, taking into account various uncertainties that arise with loads and resistances [66].…”

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

“…Tromans and van de Graaf (1994), Visser (1995), Sturm et al (1997), Bea (2000), Hansen and Gudmestad (2001), Capanoglu and Coombs (2009), Bao et al (2009), Gening and Ruiguang (2010), Håbrekke et al (2011), Solland et al (2011), Ayob et al (2014b), Kurian et al (2014a, b), George et al (2016), Kim et al (2017b) and Mohd Hairil et al (2019), have utilised the reassessment guideline from the standards to demonstrate the safety of platforms by considering ageing effects as well as the low-risk potential for environmental damage from the operation of those platforms. A study related to the decommisioned offshore platforms converted in offshore wind turbine is also recently introduced by Alessi et al (2019). Petruska (1994) has adopted the newly launched code reassessment guide on a 1950 vintage shallow water platform in GOM to assess its fitness of purpose to extend its life span.…”

“…During the analysis, the program further selects load sub-step sizes, by determining when the next stiffness change occurs and ending the sub-step at the event. This is followed by the modification of the structure stiffness and reanalysis as the next step until the entire load is being applied by Asgarian and Lesani (2009). Further detail into the specific workflow of the analysis could be found in the application manuals of the specific types of computer software such as USFOS and SACS.…”

A Numerical Investigation of an Abnormal Phenomenon of Stress Intensity Factor (SIF) in a Cracked T-Butt Joint Accounting for Welding Effect

“…In a hostile environment, the prediction of fatigue life of structures such as aircraft fuselages, pressure vessels, pipes, and modern ships becomes more and more important (Dake et al 2012;Zhang et al 2016;Alessi et al 2019;Li et al 2020). It is estimated that approximately 90% of the structural failures in engineering practice during the service life is related to fatigue failure (Shipley and Becker 2002;Bergara et al 2017).…”