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Author: P. Sincock
Publisher:
ISBN: 9780717606429
Category : Offshore structures
Languages : en
Pages : 82
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Book Description
Author: P. Sincock
Publisher:
ISBN: 9780717606429
Category : Offshore structures
Languages : en
Pages : 82
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Book Description
Author:
Publisher:
ISBN:
Category : Anchors
Languages : en
Pages : 10
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Book Description
Author: Association de recherche en géotechnique marine (France)
Publisher: Editions TECHNIP
ISBN: 9782710805724
Category : Technology & Engineering
Languages : en
Pages : 256
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Book Description
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. Taylor
Publisher:
ISBN:
Category : Anchorage
Languages : en
Pages : 71
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Book Description
This design guide provides an overview to the selection and sizing of drag embedment anchors and mooring chains and to the diagnosis and solution of typical drag anchor performance problems. The site information required for anchor type selection is outlined. Two options for sizing the drag anchor are offered. The more exacting of the options includes a method for determining the mooring load resistance developed by that length of mooring chain embedded in and sliding on cohesive seafloor soils. Example problems of anchor system design on cohesionless and cohesive seafloors are provided. The last section outlines drag anchor performance problems and provides possible solutions. More detailed information can be found in the references.
Author: Chao-Ming Chi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This study presents the applications of plastic limit analysis to offshore foundations and anchors, including the drag embedment anchors (DEAs) for mobile offshore drilling units (MODU's) and spudcan foundations for jack-up platforms. In deep waters, drag embedment anchors are an attractive option for mooring of semisubmersible platforms due to low installation cost and high holding capacity; on the other hand, jack-up platforms are more stable than semisubmersible platforms but only can be placed in shallow waters. The analyses of anchor capacities are developed for an idealized anchor comprising a rectangular fluke, a cylindrical shank, and a metal chain connected to the shank at the padeye. The anchor trajectory prediction during drag embedment is also developed by considering anchor behavior in conjunction with the mechanics of the anchor line. The results of simulations show that anchors approach at equilibrium condition rapidly during the embedment and both the normalized holding capacity and the anchor line uplift angle remain constants in this stage. Besides the geometry of the fluke, the properties of the shank and soil are also crucial factors in the anchor-soil interaction behavior. Partial failure of mooring systems for floating structures will subject drag anchors to loads having an appreciable component outside of the intended plane of loading. Partial failure of mooring systems during hurricanes in recent years has generated an interest in understanding drag anchor performance under these conditions. The analysis presents the simulations of three dimensional trajectories of an anchor system subjected to an out-of-plane load component. For the conditions simulated in the example analyses, the anchor experienced a modest amount of continued embedment following partial failure of the mooring system; however, the ultimate embedment and capacity of the anchor is much less than what would have developed if the anchor had continued in its original trajectory within the plane of intended loading. The analyses of the spudcan foundation of jack-up units include preloading, bearing capacity, and the displacement assessment. When the contribution of the soil moment resistance is considered, a three-stage assessment procedure is recommended: superposing environmental forces on the plot of yield surface, determining the value of yield function corresponding to the external forces, and computing the factor of safety of the spudcan. The results of the assessment may be ambiguous while the different yield functions are employed to analyze the spudcan in soft clay.
Author: Karan Ganjoo
Publisher:
ISBN:
Category :
Languages : en
Pages : 274
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Book Description
Mobile offshore drilling units are being used in the Gulf of Mexico to produce oil and gas. Anchoring systems such as drag embedment anchors and vertically loaded anchors are used to keep these units in place. Past mooring system failures due to hurricanes in 2004 and 2005 initiated a need to better understand the performance of these anchors to in-plane and out-of-plane loading conditions. In-plane and out-of-plane loading cause the anchor to translate or rotate in the directions of its six degrees of freedom. Behavior and holding capacity of the anchors when loaded in each of is six degrees of freedom are important in understanding and predicting their behavior. An experimental program was devised to investigate the behavior of anchors in pure translation and rotation loading. The scaled-model anchors were embedded at a measured depth in a soil bed of clay with an undrained shear strength between 10 and 20 psf and then loaded to failure. A rotation testing frame was designed to impose rotational loading in the yaw, roll and pitch directions. Test results from the experimental program are consistent and repeatable. The bearing factors for pure bearing fell well within the range of existing experimental and analytical studies on simple plates. Bearing factors for in-plane and out-of-plane shear and for all rotations are higher than those for simple plates due to presence of the shank. When the resistance is normalized by area of the fluke, the wider model provide greater normalized resistance to yawing, similar normalized resistance to pitching and rolling and less normalized resistance to bearing and shearing. It was concluded that the holding capacity of an anchor in its six degrees of freedom depends largely on its geometry, including the fluke and the shank.
Author: Amin Aslkhalili
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Drag embedment anchors and buried subsea pipelines are two important elements of the offshore field developments that are used for station-keeping of floating facilities and transferring the hydrocarbons, respectively. The lateral soil resistance against the drag anchors and pipelines are mobilized in a similar fashion with identical conventional design equations. This is fundamentally caused by similar lateral projection of the anchor and pipe geometries. The reliability assessment of the drag embedment anchors as a key component of mooring systems, and the lateral response of trenched pipelines as crucial structural elements are significantly important due to a range of uncertainties involved in the design process. Despite the similar design equations for lateral soil resistance against the moving anchor and pipe, these elements are subjected to different kinds of loadings and uncertainties that are expected to affect their reliability indices. In this study, the reliability of drag embedment anchors and laterally displaced pipelines were conducted and compared to investigate the extent of similar fashions in the lateral response of these two elements to large displacements. Both uniform and non-homogeneous soil domains were considered and compared to evaluate the impact of more realistic design scenarios. Macro spreadsheets were developed for iterative limit state and kinematic analyses and obtaining the holding capacity of drag embedment anchors. The lateral force-displacement responses of the buried pipelines were extracted from published centrifuge model tests and incorporated into finite element models in ABAQUS. Automation Python scripts were developed to perform a comprehensive series of numerical analyses and post-process the outputs to construct the required databases. Response surfaces were developed and probabilistic analyses were conducted by using the first order reliability method (FORM) to obtain the reliability indices and failure probabilities. Comparative studies were conducted to obtain an equivalent annual probability of failure between the pipelines and drag anchors. The study showed that the similar conventional approaches for modeling of the anchors and pipelines lateral displacement might be acceptable for homogeneous soil domains. However, the reliability indices were significantly affected by defining non-homogenous soil domains. It was observed that the magnitude of the reliability indices in the layered soil strata and trenched/backfilled conditions could be significantly reduced. This, in turn, revealed the need for improving the current design codes to incorporate more realistic conditions. The proposed probabilistic approach was found robust to optimize the subsea configuration of the anchors and pipelines and improve the reliability indices. The study revealed several important trends in anchors and pipeline-seabed interactions and provided an in-depth insight into its impact on reliability assessment and a safe and cost-effective design.
Author: Alain Puech
Publisher: Editions TECHNIP
ISBN: 9782710804536
Category : Technology & Engineering
Languages : en
Pages : 170
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Book Description
Author: Charles Aubeny
Publisher: CRC Press
ISBN: 1351237357
Category : Technology & Engineering
Languages : en
Pages : 515
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Book Description
This book provides a comprehensive guide for the analysis and design of anchor systems used for mooring offshore floating structures. Much of the experience is based on applications toward the offshore oil and gas industry, but the substantial potential for offshore renewable energy systems is addressed. The major types of anchors are described with respect to their basic design concept, advantages and limitations, appropriate framework for analysis, and observed performance. This book addresses all aspects of anchor behaviour related to anchor design including the installation performance, load capacity, deformation, and structural integrity of the anchor itself. Coverage is also provided of appurtenant components of anchor systems, in particular of anchor line/chain mechanics in the soil and water columns. Much of the material presented represents relatively new developments, including several new anchors which have been developed within the last decade, so the book will provide a useful compendium of information is largely scattered in journals and conference proceedings. This book is intended for engineers engaged in offshore geotechnics and marine engineers involved in mooring system and floating structure design. While the analytical methods presented in this text have a strong theoretical basis, the emphasis is on simplified computational formats accessible to design engineers.
