Final report for WP4.3: Enhancement of design methods ... - Upwind

Table of Contents
Acknowledgement.................................................................................................................... 3
Summary................................................................................................................................... 5
1. Introduction..................................................................................................................... 9
1.1 The Upwind project........................................................................................................ 9
1.2 Work Package 4: Offshore Support Structures and Foundations .................................. 9
1.3 Task 4.3: Enhancement of design methods and standards ......................................... 10
1.4 Report structure and context ....................................................................................... 10
PART I: Design Methods for Braced Bottom-Mounted Support Structures....................... 11
2. Integrated design tools ................................................................................................ 11
2.1 Coupled aero-elastic and FE approach ....................................................................... 11
2.2 Combined multi-body / modal approach ...................................................................... 13
2.3 Full Finite Element approach ....................................................................................... 15
3. Benchmarking of design tools .................................................................................... 16
3.1 Comparison of masses and frequencies...................................................................... 17
3.2 Comparison of deterministic load cases ...................................................................... 18
4. Advanced modelling approaches................................................................................ 21
4.1 Super-element modelling in ADCoS-Offshore ............................................................. 21
4.2 Results of using super-element technique................................................................... 24
5. Development of design requirements......................................................................... 32
5.1 Input to development of IEC 61400-3 standard ........................................................... 32
5.2 Reliability-based calibration of safety factors for offshore support structures .............. 39
5.3 Recommendations for offshore design load case implementation............................... 52
5.4 Design load case parameter analysis for jacket structure............................................ 58
PART II: Design Methods for Floating Support Structures ................................................. 70
6. Integrated design tools ................................................................................................ 70
6.1 Modelling methods for floating offshore wind turbines ................................................. 70
6.2 Overview of available floating design tools .................................................................. 77
7. Benchmarking of design tools .................................................................................... 82
7.1 Code-to-measurement comparisons............................................................................ 82
7.2 Code-to-code comparisons.......................................................................................... 83
7.3 Case study: testing and validation of GH Bladed v4.0 ................................................. 85
8. Advanced modelling approaches................................................................................ 89
8.1 Aerodynamic theories.................................................................................................. 90
8.2 Hydrodynamic theories................................................................................................ 93
8.3 Mooring line dynamics............................................................................................... 119
9. Development of design requirements....................................................................... 131
9.1 Literature review of floating offshore standards ......................................................... 131
9.2 Extensions to IEC 61400-3 standard for floating structures ....................................... 133
10. Conclusions ................................................................................................................ 140
References............................................................................................................................ 142
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