Dynamic Analysis Of An Offshore Wind Turbine Taking Into Account The Soil Foundation Structure Interaction
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Dynamic Analysis Of An Offshore Wind Turbine Taking Into Account The Soil Foundation Structure Interaction
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Author : Philip Alkhoury
language : en
Publisher:
Release Date : 2021
Dynamic Analysis Of An Offshore Wind Turbine Taking Into Account The Soil Foundation Structure Interaction written by Philip Alkhoury and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.
Wind energy has received a vast attention in recent years. Multi-megawatt offshore wind turbines (OWTs) mounted on large diameter monopiles are being widely used nowadays in practice. There is a general acceptance that the overall weight of OWTs must be kept to a minimum to reduce their cost. This eventually resulted in a highly flexible slender structure that is dynamically-sensitive. The high sensitivity to the highly variable external loads demands special design consideration regarding the natural frequency of the OWT system which must be outside the excitations frequencies to avoid resonance. In addition to the resonance avoidance criterion, OWTs must verify stringent serviceability design requirements during their lifetime, which demand the consideration of a reliable numerical tool with an advanced soil constitutive model for the computation of the OWT dynamic responses. Modal and dynamic analyses of such complicated structures have been well-covered in literature using different aeroelastic simulation tools based on a limited number of degrees of freedom and/or make use of simplified assumptions related to the OWT superstructure, the soil-foundation interaction and the soil behavior. In response to these challenges, this thesis presents a three-dimensional finite element (FE) model that reflects the OWT behavior to a high degree of accuracy and that is used for the computation of the OWT modal and dynamic responses. Another aim of this thesis is to study the excessive vibration mitigation of OWTs. In this regard, this thesis presents a novel technique in which FE analysis is combined with a control system to study the real-time performance of an active tuned mass damper in reducing the OWT vibrations.
Design Of Foundations For Offshore Wind Turbines
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Author : Subhamoy Bhattacharya
language : en
Publisher: John Wiley & Sons
Release Date : 2019-02-20
Design Of Foundations For Offshore Wind Turbines written by Subhamoy Bhattacharya and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-02-20 with Technology & Engineering categories.
Comprehensive reference covering the design of foundations for offshore wind turbines As the demand for “green” energy increases the offshore wind power industry is expanding at a rapid pace around the world. Design of Foundations for Offshore Wind Turbines is a comprehensive reference which covers the design of foundations for offshore wind turbines, and includes examples and case studies. It provides an overview of a wind farm and a wind turbine structure, and examines the different types of loads on the offshore wind turbine structure. Foundation design considerations and the necessary calculations are also covered. The geotechnical site investigation and soil behavior/soil structure interaction are discussed, and the final chapter takes a case study of a wind turbine and demonstrates how to carry out step by step calculations. Key features: New, important subject to the industry. Includes calculations and case studies. Accompanied by a website hosting software and data files. Design of Foundations for Offshore Wind Turbines is a must have reference for engineers within the renewable energy industry and is also a useful guide for graduate students in this area.
Structural Integrity Of Offshore Wind Turbines Oversight Of Design Fabrication And Installation
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Author : National Research Council (U.S.). Committee on Offshore Wind Energy Turbine Structural and Operating Safety
language : en
Publisher: Transportation Research Board
Release Date : 2011-09-02
Structural Integrity Of Offshore Wind Turbines Oversight Of Design Fabrication And Installation written by National Research Council (U.S.). Committee on Offshore Wind Energy Turbine Structural and Operating Safety and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-09-02 with Business & Economics categories.
"The U.S. Department of the Interior's Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE) is responsible for the orderly, safe, and environmentally responsible development of offshore renewable energy on the outer continental shelf (OCS). The Committee on Offshore Wind Energy Turbine Structural and Operating Safety that authored this report was tasked with reviewing BOEMRE's proposed approach to overseeing the design of offshore wind turbines for structural integrity. The committee was asked to review the applicability and adequacy of standards and practices that could be used for the design, fabrication and installation of offshore wind turbines. It was also asked to review the role of third-party certified verification agents (CVAs) and the expertise and qualifications needed to carry out the role of a CVA. The committee's findings are presented in the following chapters: (1) Introduction; (2) Offshore Wind Technology and Status; (3) Standards and Practices; (4) A Risk-Informed Approach to Performance Assurance; (5) Role of Third-Party Oversight and Certified Verification Agents; (6) Qualifications Needed by Certified Verification Agents; and (7) Summary of Key Findings and Recommendations."--Pub. desc.
Soil Structure Interaction Analysis Of Monopile Foundations Supporting Offshore Wind Turbines
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Author : Bipin Kumar Gupta
language : en
Publisher:
Release Date : 2018
Soil Structure Interaction Analysis Of Monopile Foundations Supporting Offshore Wind Turbines written by Bipin Kumar Gupta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Offshore wind power plants categories.
Monopile foundations supporting offshore wind turbines are hollow circular steel piles of diameter 4-6 m and a slenderness ratio (length/radius) of 10-12 driven into the seabed in an average water depth of 35 m. They are subjected to large lateral forces and overturning moments at the seabed level from wind, waves, and water currents acting on the wind turbine structure. Currently, they are designed using the p-y analysis method (p is the soil reaction force per unit length at any point along the pile shaft and y is the corresponding pile displacement at that point) which has a number of shortcomings. The p-y analysis was originally developed from a few full-scale field pile-load tests on small-diameter piles (less than 2 m in diameter) and their applicability to large-diameter monopiles is questionable. Besides, it is empirical, site-specific, and does not account for the three-dimensional pile-soil interaction important for large-diameter monopiles, thereby, resulting in a conservative design and an increase in the cost of the project. Three-dimensional finite element analysis can be used for the analysis and design of monopiles, but such analyses require significantly large computational time and effort besides, the specific expertise of finite element software that further limits its use in practice. The primary objective of this thesis is to develop a computationally efficient continuum-based mathematical model that takes the three-dimensional monopile-soil interaction into account. In the thesis, three tasks are performed towards the development of the mathematical model. First, a mathematical framework is developed to analyze laterally loaded monopiles following the Timoshenko beam theory in a multilayered elastic soil deposit subjected to static lateral loading. In the analysis, it is shown that successive simplification of the analysis can lead to monopiles modeled as a Euler-Bernoulli and rigid beam. The analysis is verified with finite element solutions and the suitability of the application each of the beam theories to obtain monopile response (head-displacement and rotation) is also investigated besides, a comparison of the computational time between the present analysis and finite element analysis is also shown. In the second task, the aforementioned framework is extended to analyze monopiles embedded in a multilayered linear viscoelastic soil deposit with frequency-independent hysteretic material damping subjected to harmonic dynamic lateral loading. It is shown that the analysis can be reduced to model monopiles following the Rayleigh, Euler-Bernoulli, and rigid beam theory. The analysis is verified with well-established solution techniques reported in the literature. Further, the results and the computational time obtained from this analysis are compared with those of the analysis in the first task for four different monopiles with varying slenderness ratio currently installed in the field. The purpose of the comparison is to investigate the applicability of the dynamic analysis for obtaining monopile response which is subjected to cyclic loadings of frequency less than 1.0 Hz. It is found that the static analysis following the Euler-Bernoulli beam theory is sufficient for obtaining monopile response. In the third task, the mathematical framework developed in the first task is extended to analyze laterally loaded monopiles modeled as a Euler-Bernoulli beam in a multilayered nonlinear elastic soil deposit and subjected to static loading. In the analysis, the nonlinear elastic relationships describing the variation of shear modulus with shear strain reported in the literature either applicable to undrained clays or sandy soil deposits are utilized. The mathematical accuracy of the analysis is verified by comparing results obtained from the analysis with the results of finite element analysis. A comparison of the computational time between the present and finite element analysis is also shown to demonstrate the computational efficiency of the present analysis. The results of the analysis are further validated with the results of several full-scale field pile-load tests and the p-y analysis procedure available in the literature. The accuracy of the results from this nonlinear elastic approach is further ensured by comparing monopile response with those of finite element simulations where the soil is modeled using an elastic-plastic constitutive model. A comparison of the monopile response is also shown in the p-y analysis to investigate the appropriateness of the currently used p-y curves to analyze and design monopiles. Finally, a preliminary step-by-step design procedure for monopile foundations embedded in nonlinear elastic soil deposit is developed following the recommendations outlined in current codes of practice for offshore wind turbines.
A Study On Soil Structure Interaction Of Offshore Wind Turbine Foundations
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Author : Georgios Nikitas
language : en
Publisher:
Release Date : 2020
A Study On Soil Structure Interaction Of Offshore Wind Turbine Foundations written by Georgios Nikitas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
On The Effect Of Offshore Wind Farms On The Atmosphere And Ocean Dynamics
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Author : Elke Ludewig
language : en
Publisher: Springer
Release Date : 2014-10-31
On The Effect Of Offshore Wind Farms On The Atmosphere And Ocean Dynamics written by Elke Ludewig and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-10-31 with Law categories.
Renewable energy resources now play an essential role in the energy supply debate, and especially a new interest in wind energy has resulted in the intensified construction of wind farms. Thanks to the growing demand for renewable energy, offshore wind farms (OWFs) are increasingly gaining in popularity, since yields over sea are greater and more reliable than over land. Against this background it is becoming particularly urgent to determine whether and if so to what extent such OWF expansion affects our oceans and local climates. OWFs produce a downstream wind speed reduction, the so-called wind-wake effect, which impacts atmospheric boundary layers, alters local wind characteristics and in turn affects ocean dynamics. This book will help readers to understand in detail these OWF-induced changes in the atmosphere and ocean by analyzing model simulations and measurements. In this context, OWF-induced upwelling and downwelling are key aspects.
Offshore Wind Energy Technology
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Author : Olimpo Anaya-Lara
language : en
Publisher: John Wiley & Sons
Release Date : 2018-05-11
Offshore Wind Energy Technology written by Olimpo Anaya-Lara and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-05-11 with Science categories.
A COMPREHENSIVE REFERENCE TO THE MOST RECENT ADVANCEMENTS IN OFFSHORE WIND TECHNOLOGY Offshore Wind Energy Technology offers a reference based on the research material developed by the acclaimed Norwegian Research Centre for Offshore Wind Technology (NOWITECH) and material developed by the expert authors over the last 20 years. This comprehensive text covers critical topics such as wind energy conversion systems technology, control systems, grid connection and system integration, and novel structures including bottom-fixed and floating. The text also reviews the most current operation and maintenance strategies as well as technologies and design tools for novel offshore wind energy concepts. The text contains a wealth of mathematical derivations, tables, graphs, worked examples, and illustrative case studies. Authoritative and accessible, Offshore Wind Energy Technology: Contains coverage of electricity markets for offshore wind energy and then discusses the challenges posed by the cost and limited opportunities Discusses novel offshore wind turbine structures and floaters Features an analysis of the stochastic dynamics of offshore/marine structures Describes the logistics of planning, designing, building, and connecting an offshore wind farm Written for students and professionals in the field, Offshore Wind Energy Technology is a definitive resource that reviews all facets of offshore wind energy technology and grid connection.
Offshore Wind Farms
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Author : María Dolores Esteban
language : en
Publisher: MDPI
Release Date : 2020-04-28
Offshore Wind Farms written by María Dolores Esteban and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-04-28 with Science categories.
The coastal zone is the host to many human activities, which have significantly increased in the last decades. However, sea level rise and more frequent storm events severely affect beaches and coastal structures, with negative consequences and dramatic impacts on coastal communities. These aspects add to typical coastal problems, like flooding and beach erosion, which already leading to large economic losses and human fatalities. Modeling is thus fundamental for an exhaustive understanding of the nearshore region in the present and future environment. Innovative tools and technologies may help to better understand coastal processes in terms of hydrodynamics, sediment transport, bed morphology, and their interaction with coastal structures. This book collects several contributions focusing on nearshore dynamics, and span among several time and spatial scales using both physical and numerical approaches. The aim is to describe the most recent advances in coastal dynamics.
Study On Offshore Wind Turbine Support Structures With Soil Structure Interaction
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Author : 劉欣雨
language : en
Publisher:
Release Date : 2020
Study On Offshore Wind Turbine Support Structures With Soil Structure Interaction written by 劉欣雨 and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Soil Structure Modeling And Design Considerations For Offshore Wind Turbine Monopile Foundations
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Author : Wystan Carswell
language : en
Publisher:
Release Date : 2015
Soil Structure Modeling And Design Considerations For Offshore Wind Turbine Monopile Foundations written by Wystan Carswell and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Offshore wind turbine (OWT) support structures account for 20-25% of the capital cost for offshore wind installations, making it essential to optimize the design of the tower, substructure, and foundation to the extent possible. This dissertation focuses on monopile foundations, as the vast majority (approximately 75%) of currently installed OWTs are supported by monopile structures. The objective of this dissertation is to provide information on the behavior of monopile support structures to better substantiate design and planning decisions and to provide a basis for reducing the structural material costs. In pursuit of these objectives, research is presented on the topics of hysteretic soil-structure damping (referred to as foundation damping), cyclic degradation of soil properties, and the impact of marine growth on OWT monopile support structures. OWTs are lightly damped structures that must withstand highly uncertain offshore wind and wave loads. In addition to stochastic load amplitudes, the dynamic behavior of OWTs must be designed with consideration of stochastic load frequency from waves and mechanical load frequencies associated with the spinning rotor during power production. The close proximity of the OWT natural frequency to excitation frequencies combined with light damping necessitates a thorough analysis of various sources of damping within the OWT system; of these sources of damping, least is known about the contributions of damping from soil-structure interaction (foundation damping), though researchers have back-calculated foundation damping from "rotor-stop" tests after estimating aerodynamic, hydrodynamic, and structural damping with numerical models. Because design guidelines do not currently recommend methods for determining foundation damping, it is typically neglected. The significance of foundation damping on monopile-supported OWTs subjected to extreme storm loading was investigated using a linear elastic two-dimensional finite element model. A simplified foundation model based on the soil-pile mudline stiffness matrix was used to represent the monopile, and hysteretic energy loss in the foundation was converted into a viscous, rotational dashpot at the mudline to represent foundation damping. The percent critical damping contributed to the OWT structural system by foundation damping was quantified using the logarithmic decrement method on a finite element free vibration time history, and stochastic time history analysis of extreme storm conditions indicated that mudline OWT foundation damping can significantly decrease the maximum and standard deviation of mudline moment. Further investigation of foundation damping on cyclic load demand for monopile-supported OWTs was performed considering the design situations of power production, emergency shutdown, and parked conditions. The NREL 5MW Reference Turbine was modeled using the aero-hydro-elastic software FAST and included linear mudline stiffness and damping matrices to take into account soil-structure interaction. Foundation damping was modeled using viscous rotational mudline dashpots which were calculated as a function of hysteretic energy loss, cyclic mudline rotation amplitude, and OWT natural frequency. Lateral monopile capacity can be significantly affected by cyclic loading, causing failure at cyclic load amplitudes lower than the failure load under monotonic loading. For monopiles in clay, undrained clay behavior under short-term cyclic soil-pile loading (e.g. extreme storm conditions) typically includes plastic soil deformation resulting from reductions in soil modulus and undrained shear strength which occur as a function of pore pressure build-up. These impacts affect the assessment of the ultimate and serviceability limit states of OWTs via natural frequency degradation and accumulated permanent rotation at the mudline, respectively. Novel combinations of existing p-y curve design methods were used to compare the impact of short-term cyclic loading on monopiles in soft, medium, and stiff clay. Marine growth increases mass and surface roughness for offshore structures, which can reduce natural frequency and increase hydrodynamic loads, and can also interfere with corrosion protection and fatigue inspections. Design standards and guidelines do not have a unified long-term approach for marine growth on OWTs, though taking into account added mass and increased drag is recommended. Some standards recommend inspection and cleaning of marine growth, but this would negate the artificial reef benefits which have been touted as a potential boon to the local marine habitat. The effects of marine growth on monopile-supported OWTs in terms of natural frequency and hydrodynamic loading are examined, and preliminary recommendations are given from the engineering perspective on the role of marine growth in OWT support structure design.