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Academic literature on the topic 'Offshore structures – Foundations'

Author: Grafiati

Published: 4 June 2021

Last updated: 21 February 2023

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Journal articles on the topic "Offshore structures – Foundations"

1

Yang, Ray-Yeng, Hsin-Hung Chen, Hwung-Hweng Hwung, Wen-Pin Jiang, and Nian-Tzu Wu. "EXPERIMENTAL STUDY ON THE LOADING AND SCOUR OF THE JACKET TYPE OFFSHORE WIND TURBINE FOUNDATION." Coastal Engineering Proceedings 1, no. 32 (January 21, 2011): 25. http://dx.doi.org/10.9753/icce.v32.structures.25.

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A 1:36 scale model tests were carried out in the Medium Wave Flume (MWF) and Near-shore Wave Basin (NSWB) at the Tainan Hydraulics Laboratory (THL) with the jacket type offshore wind turbine foundation located in the test area. The loading of typhoon wave with current on the jacket type offshore wind turbine foundation was investigated in the MWF with fixed bed experiment. Meanwhile, the scour around the jacket type offshore wind turbine foundation exposed to wave and current was conducted in the NSWB with the moveable bed experiment. Two locations (water depth 12m and 16m) of the foundations are separately simulated in this study. Based on the analysis from the former NSWB experimental results, the suitable scour protection of a four-layer work around the foundation is also proposed to the impact of scour. Finally, a four-layer scour protection is tested and found to be effective in preventing scour around jacket type foundation of offshore wind turbines at water depth 12m and 16m.

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Schneider, James A., and Marc Senders. "Foundation Design: A Comparison of Oil and Gas Platforms with Offshore Wind Turbines." Marine Technology Society Journal 44, no. 1 (January 1, 2010): 32–51. http://dx.doi.org/10.4031/mtsj.44.1.5.

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AbstractThe offshore oil and gas (O&G) industry has over 70 years of experience developing innovative structures and foundation concepts for engineering in the marine environment. The evolution of these structures has strongly been influenced by water depth as well as soil conditions in the area of initial developments. As the offshore wind industry expands from the glacial soil deposits of the North and Baltic Seas, experience from the O&G industry can be used to aid a smooth transition to new areas. This paper presents an introduction to issues that influence how design and construction experience from the O&G industry can be used to aid foundation design for offshore wind energy converters. A history of the evolution of foundation and substructure concepts in the Gulf of Mexico and North Sea is presented, followed by a discussion of soil behavior and the influence of regional geology on these developments. Mechanisms that influence the resistance of shallow and deep foundations for fixed and floating offshore structures are outlined so that areas of empiricism within offshore design codes can be identified and properly modified for application to offshore wind turbine foundations. It is concluded that there are distinct differences between offshore O&G and offshore wind turbine foundations, and application of continued research into foundation behavior is necessary for rational, reliable, and cost-effective design.

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Been, K., J. I. Clark, and W. R. Livingstone. "Verification and calibration studies for the new CAN/CSA-S472 foundations of offshore structures." Canadian Geotechnical Journal 30, no. 3 (June 1, 1993): 515–25. http://dx.doi.org/10.1139/t93-044.

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In June 1992, the Canadian Standards Association (CSA) published a code for the design, construction, and installation of fixed offshore structures. This code is relatively advanced in its application of limit states design to offshore structures. The part dealing with foundations is written as a performance standard. It does not specify resistance factors (or safety factors) to achieve the target reliability of the structure. Although limit states design is common practice among geotechnical engineers, the application of resistance factors is a problem. This paper describes some of the studies and conclusions reached by the Technical Committee in the development of the CSA foundations standard. As a first step, resistance factors were developed by calibration to conventional total factors of safety for the failure mechanisms considered. This approach has severe limitations. In particular, the applicability of safety factors developed for onshore practice or other offshore areas to the ice-dominated environment of Canadian offshore regions is questionable. In addition, many offshore structure designs include consideration of dynamic loading and scour or erosion problems that cannot be satisfactorily dealt with using factors of safety. An example of the problem of applying separate load and resistance factors for a bearing-capacity problem is given to show that load and resistance are not independent of each other. Because of the problems with development of resistance factors, the CSA foundations standard dictates that offshore structure designs include a risk analysis of the foundation system. A simple form of such an analysis for a caisson-retained sand structure is included in the paper. Key words : offshore structures, foundations, standard, safety, limit states design.

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Gao, Feng, Clive Mingham, and Derek Causon. "SIMULATION OF EXTREME WAVE INTERACTION WITH MONOPILE MOUNTS FOR OFFSHORE WIND TURBINES." Coastal Engineering Proceedings 1, no. 33 (October 15, 2012): 22. http://dx.doi.org/10.9753/icce.v33.structures.22.

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Extreme wave run-up and impacts on monopile foundations may cause unexpected damage to offshore wind farm facilities and platforms. To assess the forces due to wave run-up, the distribution of run-up around the pile and the maximum wave run-up height need to be known. This paper describes a numerical model AMAZON-3D study of wave run-up and wave forces on offshore wind turbine monopile foundations, including both regular and irregular waves. Numerical results of wave force for regular waves are in good agreement with experimental measurement and theoretical results, while the maximum run-up height are little higher than predicted by linear theory and some empirical formula. Some results for irregular wave simulation are also presented.

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Esteban, M., José-Santos López-Gutiérrez, and Vicente Negro. "Gravity-Based Foundations in the Offshore Wind Sector." Journal of Marine Science and Engineering 7, no. 3 (March 12, 2019): 64. http://dx.doi.org/10.3390/jmse7030064.

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In recent years, the offshore wind industry has seen an important boost that is expected to continue in the coming years. In order for the offshore wind industry to achieve adequate development, it is essential to solve some existing uncertainties, some of which relate to foundations. These foundations are important for this type of project. As foundations represent approximately 35% of the total cost of an offshore wind project, it is essential that they receive special attention. There are different types of foundations that are used in the offshore wind industry. The most common types are steel monopiles, gravity-based structures (GBS), tripods, and jackets. However, there are some other types, such as suction caissons, tripiles, etc. For high water depths, the alternative to the previously mentioned foundations is the use of floating supports. Some offshore wind installations currently in operation have GBS-type foundations (also known as GBF: Gravity-based foundation). Although this typology has not been widely used until now, there is research that has highlighted its advantages over other types of foundation for both small and large water depth sites. There are no doubts over the importance of GBS. In fact, the offshore wind industry is trying to introduce improvements so as to turn GBF into a competitive foundation alternative, suitable for the widest ranges of water depth. The present article deals with GBS foundations. The article begins with the current state of the field, including not only the concepts of GBS constructed so far, but also other concepts that are in a less mature state of development. Furthermore, we also present a classification of this type of structure based on the GBS of offshore wind facilities that are currently in operation, as well as some reflections on future GBS alternatives.

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Barari, Amin, and Lars Bo Ibsen. "VERTICAL CAPACITY OF BUCKET FOUNDATIONS IN UNDRAINED SOIL." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 20, no. 3 (March 10, 2014): 360–71. http://dx.doi.org/10.3846/13923730.2013.801915.

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Offshore wind turbine structures are traditionally founded on gravity concrete foundations or mono-piles. Bucket foundations were developed for the offshore oil and gas industry and are now being used in wind turbine construction. The loading in this application is characterized by a vertical load due to the slender construction combined with horizontal forces inducing a large overturning moment. Field tests on bucket foundations were performed to gain insight into the vertical load response of bucket foundations in clay soils. The field tests were accompanied by finite element numerical simulations in order to provide a better understanding of the parameters influencing bucket foundation behaviour.

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Sánchez, Sergio, José-Santos López-Gutiérrez, Vicente Negro, and M. Dolores Esteban. "Foundations in Offshore Wind Farms: Evolution, Characteristics and Range of Use. Analysis of Main Dimensional Parameters in Monopile Foundations." Journal of Marine Science and Engineering 7, no. 12 (December 2, 2019): 441. http://dx.doi.org/10.3390/jmse7120441.

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Renewable energies are the future, and offshore wind is undoubtedly one of the renewable energy sources for the future. Foundations of offshore wind turbines are essential for its right development. There are several types: monopiles, gravity-based structures, jackets, tripods, floating support, etc., being the first ones that are most used up to now. This manuscript begins with a review of the offshore wind power installed around the world and the exposition of the different types of foundations in the industry. For that, a database has been created, and all the data are being processed to be exposed in clear graphic summarizing the current use of the different foundation types, considering mainly distance to the coast and water depth. Later, the paper includes an analysis of the evolution and parameters of the design of monopiles, including wind turbine and monopile characteristics. Some monomials are considered in this specific analysis and also the soil type. So, a general view of the current state of monopile foundations is achieved, based on a database with the offshore wind farms in operation.

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Zografou, Dimitra, Susan Gourvenec, and Conleth O’Loughlin. "Vertical cyclic loading response of shallow skirted foundation in soft normally consolidated clay." Canadian Geotechnical Journal 56, no. 4 (April 2019): 473–83. http://dx.doi.org/10.1139/cgj-2018-0179.

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Skirted foundations are a potential foundation solution for a range of offshore structures, including hydrocarbon and renewable energy platforms and subsea structures. Offshore foundations can be subject to cyclic loading from environmental, installation, and operational events affecting the geotechnical response. A series of centrifuge tests have been performed on a shallow skirted foundation on normally consolidated kaolin clay under a range of vertical cyclic load sequences to investigate the effect of tensile or compressive average stress, the magnitude of the applied stress, and the effect of cyclic loading of low magnitude followed by consolidation on the foundation response. Results are presented as vertical foundation displacements normalized by the foundation geometry and interpreted within the traditional shear-strain contour approach. The findings indicate that the average, rather than maximum, vertical stress defines the foundation vertical displacement response and failure mode, a threshold stress exists below which a steady state is maintained even at a high number of cycles, and geotechnical resistance increases as a result of low-level cyclic loading followed by consolidation.

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Manzano-Agugliaro, Francisco, Miguel Sánchez-Calero, Alfredo Alcayde, Carlos San-Antonio-Gómez, Alberto-Jesús Perea-Moreno, and Esther Salmeron-Manzano. "Wind Turbines Offshore Foundations and Connections to Grid." Inventions 5, no. 1 (January 28, 2020): 8. http://dx.doi.org/10.3390/inventions5010008.

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Most offshore wind farms built thus far are based on waters below 30 m deep, either using big diameter steel monopiles or a gravity base. Now, offshore windfarms are starting to be installed in deeper waters and the use of these structures—used for oil and gas like jackets and tripods—is becoming more competitive. Setting aside these calls for direct or fixed foundations, and thinking of water depths beyond 50 m, there is a completely new line of investigation focused on the usage of floating structures; TLP (tension leg platform), Spar (large deep craft cylindrical floating caisson), and semisubmersible are the most studied. We analyze these in detail at the end of this document. Nevertheless, it is foreseen that we must still wait sometime before these solutions, based on floating structures, can become truth from a commercial point of view, due to the higher cost, rather than direct or fixed foundations. In addition, it is more likely that some technical modifications in the wind turbines will have to be implemented to improve their function. Regarding wind farm connections to grid, it can be found from traditional designs such as radial, star or ring. On the other hand, for wind generator modeling, classifications can be established, modeling the wind turbine and modeling the wind farm. Finally, for the wind generator control, the main strategies are: passive stall, active stall, and pitch control; and when it is based on wind generation zone: fixed speed and variable speed. Lastly, the trend is to use strategies based on synchronous machines, as the permanent magnet synchronous generator (PMSG) and the wound rotor synchronous generator (WRSG).

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Stahlmann, Arne, and Torsten Schlurmann. "PHYSICAL MODELING OF SCOUR AROUND TRIPOD FOUNDATION STRUCTURES FOR OFFSHORE WIND ENERGY CONVERTERS." Coastal Engineering Proceedings 1, no. 32 (January 27, 2011): 67. http://dx.doi.org/10.9753/icce.v32.sediment.67.

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As a step to further develop the share of renewable energies, the first German offshore test site alpha ventus has been installed in the North Sea in 2009 in water depths of 30 m, where experience shall be gained and made available for future offshore wind farms. Regarding converter foundations in deep water, it is well known that in most cases scour phenomena occur around the structures. Due to the complexity of the tripod foundations, significant knowledge gaps in scour progression in general and especially in detail as well as its probable effects on the stability and durability are given. Therefore, investigations on scouring phenomena around complex foundation structures like the tripod are carried out within the research project. The investigation method consists of a unique combination of local scour monitoring as well as physical and numerical modeling, whereas the physical modeling part was carried by means of 1:40 laboratory tests and 1:12 large-scale physical model tests in wave flumes. The results show that scours around the tripod foundation do not only occur directly around the foundation piles, but also in the near-field of the structure. Compared to first in-situ measured scours in the test site, at least a good qualitative agreement of the modeled scour depths and evolutions could be shown.

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Dissertations / Theses on the topic "Offshore structures – Foundations"

1

El-Gharbawy, Sherif Lotfy. "The pullout capacity of suction caisson foundations /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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Cotter, Oliver. "Installation of suction caisson foundations for offshore renewable energy structures." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534163.

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Santa, Maria Paulo Eduardo Lima de. "Behaviour of footings for offshore structures under combined loads." Thesis, University of Oxford, 1988. http://ora.ox.ac.uk/objects/uuid:50fb3d35-90b3-4685-9ace-0ec5a50014df.

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The lack of knowledge about the behaviour of footings for jack-up rigs under storm loads poses a design problem which can be tackled by model testing. The areas of prime concern are the ultimate loads on footings under combined loading, which affects the safety of the rig, and the rotational stiffness, which affects the interaction between the foundation and the structure. A programme of loading tests was performed on model footings on clay, and was divided into two stages: monotonic loading and cyclic loading. The clay samples were obtained by consolidating Speswhite kaolin slurry in cylindrical tanks 450mm in diameter. The strength and compressibility characteristics of the samples were verified by means of standard laboratory tests. The model footings were 50mm and 100mm in diameter and several shapes were tested: circular flat plate, cones of various angles and model spud-cans. Loads and displacements were monitored using appropriate instrumentation and a data logger. A series of central vertical loading tests provided data for comparison with existing bearing capacity theories. Combined loading tests were performed applying a displacement controlled horizontal load at a fixed height above the footing which was also subjected to a fixed vertical load. The main series of tests involved a parametric study of the relevant variables. Special tests allowed the assessment of the effect of embedment of the footing and the interaction of a flexible leg with the foundation. Cyclic loading tests were carried out using a load controlled system which applied a sinusoidal load simulating wave action. Effects of currents were investigated by introducing an offset to the loading cycle. The influence of amplitude and period of loading as well as the influence of vertical load were also investigated. Special tests were carried out to cover some peculiarities of real loading conditions. Fitting of a three-parameter hyperbola to the test results provided a systematic and accurate method of analysis of monotonic loading tests, leading to valuable information involving stiffness and ultimate loads. Analysis of cyclic loading tests yielded useful qualitative information regarding the progress of settlement and the variation of rotational stiffness and damping ratio with the number of cycles.

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Kirkwood, Peter Brian. "Cyclic lateral loading of monopile foundations in sand." Thesis, University of Cambridge, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709540.

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Islam, Mohammed Kabirul. "Constitutive models for carbonate sand and their application to footing problems." Phd thesis, Department of Civil Engineering, 1999. http://hdl.handle.net/2123/6428.

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Cassidy, Mark Jason. "Non-linear analysis of jack-up structures subjected to random waves." Thesis, University of Oxford, 1999. http://ora.ox.ac.uk/objects/uuid:02b96107-638b-4200-9fd7-fa49635594e3.

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There is a steadily increasing demand for the use of jack-up units in deeper water and harsher environments. Confidence in their use in these environments requires jack-up analysis techniques to reflect accurately the physical processes occurring. This thesis is concerned with the models appropriate for the dynamic assessment of jack-ups, an important issue in long-term reliability considerations. The motivation is to achieve a balanced approach in considering the non-linearities in the structure, foundations and wave loading. A work hardening plasticity model is outlined for the combined vertical, moment and horizontal loading of spudcan footings on dense sand. Empirical expressions for the yield surface in combined load space and a flow rule for prediction of footing displacements during yield are given. Theoretical lower bound bearing capacity factors for conical footings in sand have been derived and are used in a strain-hardening law to define the variation in size of the yield surface with the plastic component of vertical penetration. The complete incremental numerical model has been implemented into a plane frame analysis program named JAKUP. The spectral content of wave loading is considered using NewWave theory, and the importance of random wave histories shown by constraining the deterministic NewWave into a completely random surface elevation. Using this technique, a method for determining short-term extreme response statistics for a sea-state is demonstrated. A numerical experiment on an example jack-up and central North Sea location is shown to emphasise the difference in long-term extreme response according to various footing assumptions. The role of sea-state severity in the variation of short-term extreme response statistics is also highlighted. Finally, probabilistic methods are used to develop further understanding of the response behaviour of jack-ups. A sensitivity study of influential variables (with probabilistic formulations as opposed to deterministic values) has been conducted using the response surface methodology.

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Jardine, Richard. "Investigations of pile-soil behaviour, with special reference to the foundations of offshore structures." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/8519.

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Senders, Marc. "Suction caissons in sand as tripod foundations for offshore wind turbines." University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0163.

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[Truncated abstract] The demand for offshore wind turbines is increasing in densely populated areas, such as Europe. These constructions are typically founded on a gravity foundation or a large 'mono pile'. Gravity foundations can only be used at locations where strong soils exist and water depths are limited. Costs associated with a 'mono pile' type foundation contribute to a very large percentage of the total investment costs. This research, therefore, focuses upon a different foundation for offshore wind turbines, namely suction caissons beneath a tripod. This foundation can be used in all kinds of soil types and is cheaper than the 'mono pile' foundation, both in the amount of steel used and installation costs. Cheaper foundations can contribute to a more competitive price for offshore wind energy in comparison with other energy resources. To date, there have been relatively few studies to investigate the behaviour of this type of foundation during the installation process and during operational and ultimate loading for seabed conditions comprising dense sand. Two types of investigations were performed during this research to determine the behaviour of suction caissons beneath a tripod. Firstly, an existing computer program was extended to predict the typical loading conditions for a tripod foundation. Secondly, centrifuge tests on small scale suction caissons were performed to investigate the behaviour during the installation and loading phases. The computer program developed helped to quantify the likely ranges of environmental loading on an offshore wind turbine. For a typical 3 MW wind turbine of 90 m height, the vertical load is low at around 7 MN. During storm conditions the horizontal hydrodynamic load can be in the order of 4 MN. During normal working conditions the horizontal aerodynamic loads can reach 0.4 MN, but can increase to 1.2 MN when the pitch system malfunctions and gusts reach 30 m/s. This aerodynamic load will result in a very large contribution to the overturning moment, due to the high action point of this load. When the wind turbine is placed on top of a tripod, these large moments are counteracted by a push-pull system. ... The development of differential pressure was found to depend on the soil permeability, the extraction speed and a consolidation effect. During cyclic loading no obvious signs of a decrease in resistance were observed. During very fast cyclic loading differential pressures developed, which could increase the drained frictional resistance by approximately 40%. All centrifuge tests results were used to develop methods to predict or back calculate the installation process of suction caissons in sand and layered soil, and the behaviour during tensile and cyclic loading. These methods all use the cone resistance as the main input parameter and predict the force (or required suction) as a function of time, for a given rate of pumping or uplift displacement, in addition to the variation of suction with penetration (or force with uplift displacement). These new methods provide a useful tool in designing a reliable foundation for offshore wind turbines consisting of a tripod arrangement of suction caissons embedded in dense sand.

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Gütz, Patrick Sven [Verfasser], and Martin [Akademischer Betreuer] Achmus. "Tensile-loaded suction bucket foundations for offshore structures in sand / Patrick Sven Gütz ; Betreuer: Martin Achmus." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/122126947X/34.

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Pinna, Rodney. "Buckling of suction caissons during installation." University of Western Australia. School of Civil Engineering, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0008.

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Suction caissons are a foundation system for offshore structures which offer a number of advantages over traditional piled foundations. In particular, due to the method of installation used, they are well suited for deep-water applications. The suction caisson consists of an open ended cylindrical shell, which is installed below the seabed in a sequence which consists of two loading phases. The caisson is first installed part way under self weight, with the installation being completed by lowering the pressure within the cylinder and thus allowing the ambient water pressure to force the caisson into the ground. This thesis examines a number of structural issues which result from the form of the caisson — essentially a thin walled cylinder — and the interaction of the caisson with the surrounding soil during installation. To do this, variational analysis and nonlinear finite element analysis are employed to examine the buckling and collapse behaviour of these cylinders. In particular, two issues are considered; the influence of the open end, and the interaction between the cylinder and soil on the buckling and collapse loads. First, the behaviour of open ended cylinders is considered, where the boundary condition at the open end is allowed to vary continuously from completely free to pinned, by the use of a variable lateral spring. This lateral spring restraint may be considered to represent the intermediate restraint provided by a ring stiffener which is not fully effective. The effect of various combinations of boundary conditions is accounted for by the use of a multiplier on the lower bound to the buckling load of a cylinder with classical supports. The variable spring at the open end may also be considered to be an initial, simple representation of the effect of soil restraint on the buckling load. More complex representations of the soil restraint are also considered. A nondimensional factor is proposed to account for the influence of this spring on the buckling load. One combination of boundary conditions, where the upper end of the caisson is pinned, and the lower end free (referred to as a PF boundary condition), is found to have buckling and collapse behaviour which is unusual for cylindrical shells. Buckling loads for such shells are much lower than would be found for cylinders with more typical boundary conditions, and of similar dimensions. More unusually however, PF cylinders are shown to have positive postbuckling strength. The behaviour is found to be a result of the large flexibility which results from the low restraint provided by the PF boundary conditions. This is shown by continuously decreasing the flexibility of the cylinder, by increasing the axial restraint at the pinned end. It is shown that this results in a large increase in buckling load, and a return to more usual levels of imperfection sensitivity. In particular, with an intermediate level of axial restraint, buckling loads and imperfection sensitivity are intermediate between those of PF shells with no, and with full, axial restraint. Overall however, collapse loads for PF cylinders with no additional restraint are well below those of cylinders with stiffer boundary conditions, for equal geometries. Eigenvalue buckling of cylinders fully and partially embedded in an elastic material are examined, and two analytical solutions are proposed. One of these is an extension of a method previously proposed by Seide (1962), for core filled cylinders, to pin ended cylinders which have support from both a core and a surrounding material. The second method represents the elastic support as a two parameter foundation. While more approximate than the first method, this method allows for the examination of a wider range of boundary conditions, and of partial embedment. It is found that the buckling load of the shell/soil system decreases as the embedment ratio decreases. Collapse of fully and partially embedded cylinders is also examined, using nonlinear finite element analysis. The influence of plasticity in the soil is also considered. For cylinders with small imperfections, it is found that the collapse load shows a large increase over that of the same cylinder with no soil support. However, as the size of initial geometric imperfections increases, it is found that the collapse load rapidly approaches that of the unsupported cylinder. In particular, in weak soils the gain in strength over the unsupported shell may be minimal. The exception to this is again PF cylinders. As these have relatively low collapse loads, even very weak soils are able to offer an increase in collapse load over the unsupported case. Finally, a summary of these results is provided in the form of guidance for design of such structures.

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Books on the topic "Offshore structures – Foundations"

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Magued, Iskander, Laefer Debra F, Hussein Mohamad H, American Society of Civil Engineers. Geo-Institute, Association of Drilled Shaft Contractors (U.S.), and Pile Driving Contractors Association (U.S.), eds. Contemporary topics in deep foundations: Selected papers from the 2009 International Foundation Congress and Equipment Expo, March 15-19, 2009, Orlando, Florida. Reston, Va: American Society of Civil Engineers, 2009.

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Deepwater foundations and pipeline geomechanics. Ft. Lauderdale, FL: J. Ross Pub., 2011.

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Scour at marine structures: A manual for practical applications. London: Thomas Telford, 1998.

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Jørgen, Fredsøe, ed. The mechanics of scour in the marine environment. River Edge, N.J: World Scientific, 2002.

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Semple, R. M. Background to guidance on foundations and site investigations for offshore structures: Report of the Department of Energy, Guidance Notes Revision Working Group. London: H.M.S.O., 1986.

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Bhattacharya, Subhamoy. Design of Foundations for Offshore Wind Turbines. Wiley & Sons, Incorporated, John, 2019.

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Bhattacharya, Subhamoy. Design of Foundations for Offshore Wind Turbines. Wiley & Sons, Incorporated, John, 2019.

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Bhattacharya, Subhamoy. Design of Foundations for Offshore Wind Turbines. Wiley, 2019.

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Bhattacharya, Subhamoy. Design of Foundations for Offshore Wind Turbines. Wiley & Sons, Limited, John, 2019.

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Semple, R. M. Background to Guidance on Foundations and Site Investigations for Offshore Structures. Stationery Office Books, 1986.

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Book chapters on the topic "Offshore structures – Foundations"

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Hart, William Brook, Rebecca Cook, and John Harris. "Competitive concrete gravity base foundations for offshore wind farms." In Coasts, marine structures and breakwaters: Adapting to change, 2: 62–73. London: Thomas Telford Ltd, 2010. http://dx.doi.org/10.1680/cmsb.41318.0007.

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Yong, Fion, and Neil Morgan. "Challenges of Life Extension for Offshore Structures and Foundations." In Lecture Notes in Civil Engineering, 606–11. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2306-5_86.

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Chambel, J., T. Fazeres-Ferradosa, A. M. Bento, F. Taveira-Pinto, and P. Lomónaco. "Experimental study of long-term scour damage for protected offshore wind foundations." In Advances in the Analysis and Design of Marine Structures, 235–44. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003399759-26.

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Gudmestad, Ove Tobias. "Fabrication of Concrete Gravity Foundations as Support Structures for Offshore Wind Turbine Facilities." In Lecture Notes in Civil Engineering, 493–500. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7735-9_55.

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Chaney, Ronald C., and Kenneth R. Demars. "Offshore Structure Foundations." In Foundation Engineering Handbook, 679–734. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3928-5_18.

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Jia, Junbo. "Offshore Structures and Hydrodynamic Modeling." In Soil Dynamics and Foundation Modeling, 269–313. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-40358-8_9.

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Mahanta, Rupam, and R. K. Ghanekar. "Foundation Failure and Instability of an Offshore Jacket Structure During Installation—A Case Study." In Advances in Offshore Geotechnics, 207–19. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-6832-9_10.

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Jiang, Meng, Lihua Han, and Rixiang Zhang. "Study on Design and Mechanics of Bucket Foundation Offshore Platform with Two Pillars." In Computational Structural Engineering, 1155–62. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-2822-8_130.

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Kerner, Laura, Jean-Claude Dupla, Gwendal Cumunel, Pierre Argoul, Jean Canou, and Jean-Michel Pereira. "Experimental Study on a Scaled Model of Offshore Wind Turbine on Monopile Foundation." In Springer Series in Solid and Structural Mechanics, 249–67. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-48884-4_14.

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Fonseca, Joana, Sadegh Nadimi, and Deqiong Kong. "Image-Based Modelling of Shelly Carbonate Sand for Foundation Design of Offshore Structures." In Lecture Notes in Civil Engineering, 55–60. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2306-5_5.

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Conference papers on the topic "Offshore structures – Foundations"

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Byrne, B. W., and G. T. Houlsby. "Investigating Novel Foundations for Offshore Windpower Generation." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28423.

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In recent years there has been a worldwide increase in the pressure to develop sources of renewable energy. The UK government is committed to ensuring that ten percent of UK energy consumption will be supplied by renewables by the year 2010. Central to this commitment is the need to develop wind farms particularly in the offshore environment. Moving offshore will allow very large wind turbines capable of supplying 2 MW (first generation) to 5 MW (second generation) of power to be installed in large farms consisting of up to fifty or more turbines. In contrast to typical oil and gas structures the foundation may account for up to forty percent of the projected installed cost. The weight of each structure is very low, so the applied vertical load on the foundation will be small compared to the moment load derived from the wind and waves. Further, it will be necessary to have a single design that can be mass-produced over each site rather than have each foundation individually engineered. In combination these points lead to a very interesting engineering problem where the design of the foundation becomes crucial to the economics of the project. One solution is to use conventional piling. However, at some sites it may prove more economical to use shallow foundations, and, in particular suction installed skirted foundations [1]. It will be necessary to develop an adequate design framework for these no vel foundations under the relevant combinations of load so that the optimum structural configuration can be achieved. At Oxford University a program of research on skirted foundations has been underway for the last five years, and much progress has been made on the understanding of this type of foundation under combined loading. This progress has been in both experimental and theoretical areas. This paper explores various structural options that might be used for the wind turbine application. These different options lead to different loading conditions on the foundations. Experiments investigating these different loading conditions are explored. A theoretical approach that describes the experimental results in a way that can be implemented in typical structural analyses programs is outlined. Finally details of a major research program into developing the necessary design guidelines for foundations for offshore wind turbines is described.

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Hwang, Jeongwoo, Ja-Hoon Lee, and Yong-Sik Cho. "Numerical Prediction of Scouring Depth Around Foundations of Offshore Structures." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41474.

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The pile foundations of offshore structures are vulnerable to local ground loss by scouring. The vortex flow affected by the flow conditions, ground conditions, and the shape of the pile is the main cause of scouring. The decrease of an embedded depth of foundation pile by scouring may lead to an excessive displacement of the structure and a decrease of the bearing power, leading to a collapse of the offshore structure. In this work, a three-dimensional commercial code named STAR-CCM+ has been employed to predict the final depth of the scouring-hole around the foundation of offshore structures. Assuming the bed as a fluid having a high level of dynamic viscosity and density, the prediction has been accomplished by using the multi-phase flow model. The model solves the Reynolds Averaged Navier-Stokes (RANS) equations, and standard k-ε turbulence model to estimate the depth of the scouring-hole. To guarantee the reliability of the model, the results of the numerical model have been compared with available laboratory measurements. A reasonable agreement has been observed.

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Tavouktsoglou, Nicholas S., John M. Harris, Richard R. Simons, and Richard J. S. Whitehouse. "Bed Shear Stress Distribution Around Offshore Gravity Foundations." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41966.

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Offshore gravity foundations are often designed with complex geometries. Such structures interact with the local hydrodynamics and generate enhanced bed shear stresses and flow turbulence capable of scouring the seabed or destabilizing bed armour where deployed. In the present study a novel bed shear stress measurement method has been developed from the camera and laser components of a Particle Image Velocimetry (PIV) system. The bed shear stress amplification was mapped out around six models of gravity foundations with different geometries. Tests were repeated for two bed roughness conditions. The structures tested included uniform cylinders, cylindrical base structures and conical base structures. The flow field around the models was also measured using PIV. The results of this study reveal that the conical base structures generate a different hydrodynamic response compared to the other structures. For uniform cylinders the maximum bed shear stress amplification occurs upstream, at an angle of 45° relative to the flow direction, and measurements were found to agree well with numerical results obtained by Roulund et al. (2005). In the case of the cylindrical base structure the maximum amplification occurs upstream at a similar location to the uniform cylinder case. For the conical base structures the maximum amplification of the bed shear stress occurs on the lee side of the structure, with the magnitude dependent on the side slope of the cone. The bed shear stress results were validated against stresses derived from analysis of the flow fields obtained by the PIV measurements performed under the same test conditions. Conclusions from the study are that the structure with the cylindrical base foundation produces the lowest bed shear stress amplification and that an increase in the bed roughness results in an increase in the amplification of the bed shear stress. These findings have direct implications for design of scour protection. In addition the flow reattachment point behind the foundation is dependent on pile Reynolds number (ReD). This suggests that the results of this study may be extrapolated for higher pile Reynolds using the method described in Roulund et al. (2006).

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de Freitas Fagundes, Diego, Maria Cascão F. Almeida, Marcio S. S. Almeida, and Khader I. Rammah. "Physical Modelling of Offshore Structures Founded on Sea Bed." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83265.

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This work presents an experimental study using centrifuge modelling on mudmat shallow foundations which are mainly used to support offshore subsea equipment. An optimized design of these foundations requires the maximizing of the ratio between the installation and the pull-out resistance of the foundation. International standards, based on classical theories, are often limited and do not meet the complexity of the projects. The bibliography is not yet conclusive about the load capacity factors for this particular problem. In this work, physical modelling has been performed on both perforated and solid mudmats subjected to vertical load and simulating both installation and extraction scenarios. The soil used in this study is a marine clay taken from the Roncador field at Campos basin located offshore of the state of Rio de Janeiro, Brazil. The physical modelling experiments have been carried out on the mini-drum geotechnical centrifuge at COPPE/UFRJ. The technique of lumps was adopted for the preparation of the soil models and a temporary surcharge using a sand layer has been applied to develop a soil strength profile similar to the one found in the field. The results obtained in this study provided a better understanding of the soil-structure interaction problem with regard to the installation and pull-out resistance of the studied type of foundation focusing on their bearing capacity factors.

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Bush, Erica, and Lance Manuel. "Models for Offshore Wind Turbine Foundations and Their Influence on Long-Term Loads." In Structures Congress 2009. Reston, VA: American Society of Civil Engineers, 2009. http://dx.doi.org/10.1061/41031(341)280.

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Bughi, Sabrina, and Eric Parker. "Suction Pile Foundations: Experience in the Mediterranean Offshore and Installation Feedback." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49871.

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Suction piles are widely used in deepwater engineering both for anchoring and as foundation systems. In the first case the piles serve as anchor points for mooring systems in alternative to more standard drag anchors or piles. More recently, however, they have been used as structure foundations. In this role suction piles are a competitive alternative to the more traditional solutions of driven piles or mudmats, for platform jackets, subsea systems and subsea equipment protection structures. This solution provides cost savings in fabrication and required installation equipment. Furthermore, the foundations are relatively easy and rapid to install and can be positioned with high precision by controlled and simple marine operations, and they can be removed for reuse. This paper describes the use of steel suction piles for deepwater subsea Manifolds, Tie-in Spool Bases and Subsea Control Distribution Assemblies, in the West Delta Deep Marine (WDDM) and Rosetta concessions offshore Egypt. Most of the structures were supported by a single suction pile foundation; pile diameters ranged from 4 m to 8 m and penetrations from 8 m to 12 m. One of the larger units was supported by a “quad” foundation frame with four suction piles. Soils in the area are very soft, normally consolidated clays typical of deepwater conditions. Design is complicated by seismicity of the area, which required the foundations to resist significant horizontal dynamic loads in addition to the normal vertical operating loads. The solution adopted utilized an internal top plate in contact with the soil allowing full development of base bearing capacity. As the pile skin friction in these soils is very low, the increased end bearing leads to significant savings on foundation weight and cost. The paper discusses the main aspects of foundation design, covering the installation process with expected self weight penetration and the required suction to achieve the target design penetration, the retrieval operation for repositioning in case the final inclination is out of tolerance, the assessment of the bearing capacity and the stability under the combined vertical, horizontal and overturning loads during operation and earthquake conditions. Seismic design was based on a nonlinear dynamic analysis. In some cases the seismic loads were comparable to the ultimate foundation capacity and the final acceptance criteria utilized a Performance Based Design philosophy. In this approach the foundation is considered acceptable if the deformation experienced by the structure, during and after the seismic event, does not jeopardize structural integrity.

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Wåsjø, Kasper, Morten Bjerkås, and Tore Søreide. "Steel Jackets and Monotower Foundations for Offshore Wind Turbines." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83615.

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Steel jacket support structures for offshore wind have an increasing popularity for water depths larger than 20 m. Traditionally, support structures such as monopiles and gravity based foundation have dominated at shallow water. Offshore wind industry deals gradually with larger water depths, and light weight foundations as steel jackets are believed to give a cost benefit. The present study shows that the quasi static overturning moment for monotower structures and steel jackets are of comparable magnitude. It is also shown that the most important benefit of steel jackets as support structures is to reduce the base shear. At last it is shown that foundation size is primarily driven by wave and current loads at water depth around 50–60 m.

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Chatterjee, Prabir Kumar. "Single-Pile Offshore Structures as a Cost-Effective Alternative to Small Fixed Platforms in Shallow Water." In International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21427-ms.

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Abstract The present paper proposes an alternative to small offshore platforms with tripods and four-legged jackets by a single-pile structure for shallow water depths. The pile will be driven into seabed without a jacket and stability of the structure against environmental loads will be ensured by a few tie members connected to seabed with the help of specially-designed small concrete foundations. Tie members will be bolted to both the pile and the foundation. Four different cases of single-pile structures in three different water depths (20.0m, 31.5m and 15.0m) are presented. Omnidirectional waves of 10.0m height along with wind and current are considered in the study. Analytical method is suggested to simulate interaction of concrete foundations with soil that can be easily implemented in structural analysis. Structural design is performed as per API RP 2A working stress design method. The results indicate that the proposed single-pile structures have considerable reserve strength against failure due to extreme environmental loads and impact from medium sized boats.

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Yun, G. J., J. Oliphant, A. Maconochie, and A. Ahmad. "The Bearing Capacity of a Skirted Two-Foundation System." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20361.

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A foundation system comprising two closely spaced skirted rigidly connected foundations has been developed for in-line subsea structures on a number of offshore deepwater development projects off the west coast of Africa. Here the pipeline and its holding system are placed between the foundations and allowed to rest on the seabed during operation. This type of foundation system produces benefits during installation as the hydrodynamic forces on the structure are reduced and in operation a greater stability is achieved through a lower system centre of gravity. In addition, as the pipeline interacts with the seabed between the foundations, some of the pipeline loading is carried by the soil rather than the foundation system. There is no established design methodology for these foundation systems. Full interaction between the skirted two-foundation system occurs as the soil between them is constrained. Therefore, efficiencies in the vertical bearing capacity of a spaced skirted foundation system can be mobilised through foundation interaction provided by the structural connection. Previous work on uniform clay found that a maximum vertical bearing capacity efficiency of 1.05 was observed when the spacing between the two foundations or footings was approximately 0.25B. A series of plain strain FE analyses have been conducted to investigate the vertical bearing capacity of a skirted two-foundation system. Both uniform and non-uniform clay models have been studied. A parametric study has also been done to investigate the influence of the size of the spacing between foundations and skirt lengths on the overall foundation capacity.

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Parker, Eric J., Fabrizio Ardoino, and Sabrina Bughi. "Performance Based Seismic Design of Suction Pile Foundations." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11465.

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Deepwater subsea developments require installation of relatively large, heavy structures in poor soil conditions. In many cases, the foundations of choice are large diameter suction piles. The industry has excellent experience in design of these foundations for operational conditions, but offshore codes provide little guidance regarding performance during earthquakes. This paper presents an example of a recent project where suction piles were used to support large manifold structures in a seismically active region. Preliminary verifications using a conventional pseudostatic approach showed that the planned foundations would have been unsatisfactory for seismic loadings. More detailed performance based design was employed to avoid over-dimensioning the piles. Dynamic finite element analysis was used to evaluate structure displacements during and after the design earthquake. Advanced soil models were required to capture the nonlinear behavior of the soft soils at the site. The manifold displacements were compared to operational requirements to assess foundation acceptability. The approach provided considerable savings. This paper outlines the main aspects of the two approaches, and shows the advantages of performance based design for these structures. Our conclusion is that careful analysis is required for the soil conditions typically found at deepwater sites; standard simplified approaches may not suffice.

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Reports on the topic "Offshore structures – Foundations"

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Yokel, Felix Y., and Robert G. Bea. Mat foundations for offshore structures in Arctic regions. Gaithersburg, MD: National Bureau of Standards, 1987. http://dx.doi.org/10.6028/nbs.ir.86-3419.

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