book

Design of Foundations for Offshore Wind Turbines

by Subhamoy Bhattacharya

April 2019

Intermediate to advanced

392 pages

11h 41m

English

Wiley

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1.1 Harvesting Wind Energy1.2 Current Scenario1.3 Components of Wind Turbine Installation1.4 Control Actions of Wind Turbine and Other Details1.5 Foundation Types1.6 Foundations in the Future1.7 On the Choice of Foundations for a Site1.8 General Arrangement of a Wind Farm1.9 General Consideration for Site Selection1.10 Development of Wind Farms and the Input Required for Designing Foundations1.11 Rochdale Envelope Approach to Foundation Design (United Kingdom Approach)1.12 Offshore Oil and Gas Fixed Platform and Offshore Wind Turbine Structure1.13 Chapter Summary and Learning Points
2.1 Dynamic Sensitivity of Offshore Wind Turbine Structures2.2 Target Natural Frequency of a Wind Turbine Structure2.3 Construction of Wind Spectrum2.4 Construction of Wave Spectrum2.5 Load Transfer from Superstructure to the Foundation2.6 Estimation of Loads on a Monopile‐Supported Wind Turbine Structure2.7 Order of Magnitude Calculations of Loads2.8 Target Natural Frequency for Heavier and Higher‐Rated Turbines2.9 Current Loads2.10 Other Loads2.11 Earthquake Loads2.12 Chapter Summary and Learning Points
3.1 Introduction3.2 Modes of Vibrations of Wind Turbine Structures3.3 Effect of Resonance: A Study of an Equivalent Problem3.4 Allowable Rotation and Deflection of a Wind Turbine Structure3.5 Internationals Standards and Codes of Practices3.6 Definition of Limit States3.7 Other Design Considerations Affecting the Limit States3.8 Grouted Connection Considerations for Monopile Type Foundations3.9 Design Consideration for Jacket‐Supported Foundations3.10 Design Considerations for Floating Turbines3.11 Seismic Design3.12 Installation, Decommission, and Robustness3.13 Chapter Summary and Learning Points
4.1 Introduction4.2 Hazards that Needs Identification Through Site Investigation4.3 Examples of Offshore Ground Profiles4.4 Overview of Ground Investigation4.5 Cone Penetration Test (CPT)4.6 Minimum Site Investigation for Foundation Design4.7 Laboratory Testing4.8 Behaviour of Soils under Cyclic Loads and Advanced Soil Testing4.9 Typical Soil Properties for Preliminary Design4.10 Case Study: Extreme Wind and Wave Loading Condition in Chinese Waters
5.1 Soil–Structure Interaction (SSI) for Offshore Wind Turbines5.2 Field Observations of SSI and Lessons from Small‐Scale Laboratory Tests5.3 Ultimate Limit State (ULS) Calculation Methods5.4 Methods of Analysis for SLS, Natural Frequency Estimate, and FLS5.5 Long‐Term Performance Prediction for Monopile Foundations5.6 Estimating the Number of Cycles of Loading over the Lifetime5.7 Methodologies for Long‐Term Rotation Estimation5.8 Theory for Estimating Natural Frequency of the Whole SystemChapter Summary and Learning Points
6.1 Flow Chart of a Typical Design Process6.2 Target Frequency Estimation6.3 Stiffness of a Monopile and Its Application6.4 Stiffness of a Mono‐Suction Caisson6.5 Mudline Moment Spectra for Monopile Supported Wind Turbine6.6 Example for Monopile Design

Content preview from Design of Foundations for Offshore Wind Turbines

Appendix DGuidance on Estimating the Vertical Stiffness of Foundations

Methods to estimate the vertical stiffness of the foundation in literature:

Source	Formulae and their applications
Surface foundation	Poulos and Davis (1974) Spence (1968)	Circular rigid footing on surface of homogenous elastic half‐space To account for the roughness of the footing base that allow full transmission of shear stress, Spence (1968) proposed; The results from this analytical solution showed up to 10% increase in stiffness values at low ѵ_s values.
Gazetas (1983) DNV (2014)	Circular footing on stratum over half space
Shallow embedded foundation	Gazetas (1991) DNV (2014)	Circular rigid footing embedded in homogenous stratum over bedrock. Developed for machine‐type inertial loading. Range of validity: L/D < 1
Wolf (1988)	General prismatic footing embedded in a linear elastic half space Where 2l, 2b are the base dimensions of circumscribed rectangle and e is the embedment depth.