Reliability Assessment of Foundations for Offshore Mooring Systems Under Extreme Environments PDF Download
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Author: Young Jae Choi
Publisher:
ISBN:
Category : Deep-sea moorings
Languages : en
Pages : 406
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Book Description
Mooring systems for floating facilities that are used offshore to produce oil and gas, consisting of individual mooring lines and foundations, are currently designed on the basis of individual components and on a case-by-case basis. The most heavily loaded line and anchor are checked under extreme loading conditions (hurricane and loop current) with the system of lines intact and with one line removed. However, the performance of the entire mooring system depends more directly on the performance of the system of lines and foundations rather than on the performance of a single component. In this study, a floating production system design originally developed by the industry consortium, DeepStar, was chosen for study. The mooring system was designed for three different nominal water depths: 1000, 2000 and 3000 m. It is a classic spar with steel mooring lines in 1000 m of water and polyester mooring lines in deeper depths. Based on simulated results of loads on mooring lines and foundations using a numerical model, reliability analyses were conducted using representative probabilistic descriptions of the extreme met-ocean conditions, hurricanes and loop currents, in the Gulf of Mexico. The probability of failure of individual mooring line components during a 20-year design life is calculated first, followed by that of a complete mooring line which consists of top and bottom chains, a steel cable or polyester rope at the middle and a suction caisson foundation, and finally that of the mooring system. It is found that foundations have failure probabilities that are more than an order of magnitude smaller than those for lines under extreme loading. Mooring systems exhibit redundancy in that the failure of the most heavily loaded component during an extreme event does not necessarily lead to failure of the system. The system reliability and redundancy are greater for the taut versus semi-taut systems and is greater for designs governed by loop current versus hurricane events. Although this study concerns about the mooring systems of a classical spar, the methodology of the reliability analysis and the conclusions made in this study may have important implications to the other deepwater mooring systems.
Author: Young Jae Choi
Publisher:
ISBN:
Category : Deep-sea moorings
Languages : en
Pages : 406
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Book Description
Mooring systems for floating facilities that are used offshore to produce oil and gas, consisting of individual mooring lines and foundations, are currently designed on the basis of individual components and on a case-by-case basis. The most heavily loaded line and anchor are checked under extreme loading conditions (hurricane and loop current) with the system of lines intact and with one line removed. However, the performance of the entire mooring system depends more directly on the performance of the system of lines and foundations rather than on the performance of a single component. In this study, a floating production system design originally developed by the industry consortium, DeepStar, was chosen for study. The mooring system was designed for three different nominal water depths: 1000, 2000 and 3000 m. It is a classic spar with steel mooring lines in 1000 m of water and polyester mooring lines in deeper depths. Based on simulated results of loads on mooring lines and foundations using a numerical model, reliability analyses were conducted using representative probabilistic descriptions of the extreme met-ocean conditions, hurricanes and loop currents, in the Gulf of Mexico. The probability of failure of individual mooring line components during a 20-year design life is calculated first, followed by that of a complete mooring line which consists of top and bottom chains, a steel cable or polyester rope at the middle and a suction caisson foundation, and finally that of the mooring system. It is found that foundations have failure probabilities that are more than an order of magnitude smaller than those for lines under extreme loading. Mooring systems exhibit redundancy in that the failure of the most heavily loaded component during an extreme event does not necessarily lead to failure of the system. The system reliability and redundancy are greater for the taut versus semi-taut systems and is greater for designs governed by loop current versus hurricane events. Although this study concerns about the mooring systems of a classical spar, the methodology of the reliability analysis and the conclusions made in this study may have important implications to the other deepwater mooring systems.
Author: Mir Emad Mousavi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This study proposes new methods for the reliability-based design of structural systems, with emphasis on offshore mooring systems. After a brief introduction to the mooring systems, two main objectives are discussed in this dissertation. The first objective is the calculation of the probability of failure of a structural system, which is an important input for a reliability-based design or any quantitative risk assessment. Two different methods are proposed for calculation of the probability of failure: a method based on the Monte Carlo simulations and a method based on the basic rules of probability, which is called the Progressive Reliability Method (PRM). Both methods are flexible to the definition of system failure. For example, the probability of a serviceability or ultimate-strength failure can be assessed using any of the two methods. It is shown that the two methods produce similar results, but PRM is preferred because it is exact and usually faster to implement. The second main objective in this dissertation is to develop a method for the optimization of the design of a structural system, given a target probability of failure. In this method, using the structural analysis of a preliminary design, the ratio of the optimal to the preliminary mean capacity of each component, which is called the Optimality Factor, is determined. Two design strategies are considered. First, an optimal design is intended to achieve the maximum system integrity. System integrity is defined as the balanced contribution of system components to its reliability. To quantify the system integrity, the Integrity Index is defined, and its calculation for various systems is discussed. Second, a designated failure scenario is considered, where some components serve as a fuse to protect some other components. This design strategy is especially applicable to mooring systems with drag anchor foundations because normally, if a drag anchor is pulled out from the seabed, it can cause significant damages to nearby subsea facilities. Using the rules of probability, a method is then developed to calculate the optimality factor of each component. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149292
Author: Kai-Tung Ma
Publisher: Gulf Professional Publishing
ISBN: 012818552X
Category : Science
Languages : en
Pages : 350
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Book Description
The mooring system is a vital component of various floating facilities in the oil, gas, and renewables industries. However, there is a lack of comprehensive technical books dedicated to the subject. Mooring System Engineering for Offshore Structures is the first book delivering in-depth knowledge on all aspects of mooring systems, from design and analysis to installation, operation, maintenance and integrity management. The book gives beginners a solid look at the fundamentals involved during mooring designs with coverage on current standards and codes, mooring analysis and theories behind the analysis techniques. Advanced engineers can stay up-to-date through operation, integrity management, and practical examples provided. This book is recommended for students majoring in naval architecture, marine or ocean engineering, and allied disciplines in civil or mechanical engineering. Engineers and researchers in the offshore industry will benefit from the knowledge presented to understand the various types of mooring systems, their design, analysis, and operations. Understand the various types of mooring systems and the theories behind mooring analysis Gain practical experience and lessons learned from worldwide case studies Combine engineering fundamentals with practical applications to solve today’s offshore challenges
Author: R. B. Bush
Publisher:
ISBN:
Category : Drilling platforms
Languages : en
Pages : 78
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Book Description
Author:
Publisher:
ISBN:
Category : Ocean engineering
Languages : en
Pages : 444
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Book Description
Author: Guedes Soares Carlos
Publisher: CRC Press
ISBN: 1000318737
Category : Technology & Engineering
Languages : en
Pages : 819
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Book Description
Developments in Renewable Energies Offshore contains the papers presented at the 4th International Conference on Renewable Energies Offshore (RENEW 2020, Lisbon, Portugal, 12 - 15 October 2020). The book covers a wide range of topics, including: resource assessment; wind energy; wave energy; tidal energy; ocean energy devices; multiuse platforms; PTO design; grid connection; economic assessment; materials and structural design; installation planning and maintenance planning. The book will be invaluable to professionals and academics involved or interested in Offshore Engineering, and Renewable and Wind Energy.
Author: Carlos Guedes Soares
Publisher: CRC Press
ISBN: 1000459047
Category : Technology & Engineering
Languages : en
Pages : 846
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Book Description
This set of two volumes comprises the collection of the papers presented at the 5th International Conference on Maritime Technology and Engineering (MARTECH 2020) that was held in Lisbon, Portugal, from 16 to 19 November 2020. The Conference has evolved from the series of biennial national conferences in Portugal, which have become an international event, and which reflect the internationalization of the maritime sector and its activities. MARTECH 2020 is the fifth of this new series of biennial conferences. The set comprises 180 contributions that were reviewed by an International Scientific Committee. Volume 2 is dedicated to ship performance and hydrodynamics, including CFD, maneuvering, seakeeping, moorings and resistance. In addition, it includes sections on ship machinery, renewable energy, fishing and aquaculture, coastal structures, and waves and currents.
Author: University of Illinois (Urbana-Champaign campus). Engineering Experiment Station
Publisher:
ISBN:
Category : Engineering
Languages : en
Pages : 384
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Book Description
Author:
Publisher:
ISBN:
Category : Petroleum
Languages : en
Pages : 536
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Book Description
Author: James F. Wilson
Publisher: John Wiley & Sons
ISBN: 0471275654
Category : Technology & Engineering
Languages : en
Pages : 343
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Book Description
Unique, cutting-edge material on structural dynamics and natural forces for offshore structures Using the latest advances in theory and practice, Dynamics of Offshore Structures, Second Edition is extensively revised to cover all aspects of the physical forces, structural modeling, and mathematical methods necessary to effectively analyze the dynamic behavior of offshore structures. Both closed-form solutions and the Mathematica(r) software package are used in many of the up-to-date example problems to compute the deterministic and stochastic structural responses for such offshore structures as buoys; moored ships; and fixed-bottom, cable-stayed, and gravity-type platforms. Throughout the book, consideration is given to the many assumptions involved in formulating a structural model and to the natural forces encountered in the offshore environment. These analyses focus on plane motions of elastic structures with linear and nonlinear restraints, as well as motions induced by the forces of currents, winds, earthquakes, and waves, including the latest theories and information on wave mechanics. Topics addressed include multidegree of freedom linear structures, continuous system analysis (including the motion of cables and pipelines), submerged pile design, structural modal damping, fluid-structure-soil interactions, and single degree of freedom structural models that, together with plane wave loading theories, lead to deterministic or time history predictions of structural responses. These analyses are extended to statistical descriptions of both wave loading and structural motion. Dynamics of Offshore Structures, Second Edition is a valuable text for students in civil and mechanical engineering programs and an indispensable resource for structural, geotechnical, and construction engineers working with offshore projects.
