1. Design and Calculus of the Foundation Structure of an Offshore Monopile Wind Turbine
Author: Carlos Garcés García
Directed by: Julio García Espinosa

2. Contents Introduction Wind Turbine Emplacement Loads Grout Connection
Transition Piece
Monopile
Foundation
Loads Analysis
Conclusions

3. Monopile A Monopile? Its Parts Function The Pile The Grout
The Transition Piece
Function

4. The Offshore Wind Turbine
NREL 5MW Wind Turbine
Rating
5 MW
Rotor Orientation, Configuration
Upwind, 3 Blades
Control
Variable Speed, Collective Pitch
Drivetrain
High Speed, Multiple-Stage Gearbox
Rotor
126 m
Hub Diameter
3 m
Hub Height
90 m
Cut-In, Rated, Cut-Out Wind Speed
3 m/s, 11.4 m/s, 25 m/s
Cut-In, Rated Rotor Speed
6.9 rpm, 12.1 rpm
Rated Tip Speed
80 m/s
Overhang, Shaft Tilt, Precone
5 m, 5º, 2.5º
Rotor Mass
110,000 kg
Coordinate Location of Overall Center of Mass
(-0.2 m, 0.0 m, 64.0 m)

5. Emplacement Localisation: 39º 15’N, 74º 15’W
Average Wind Speed: 6,38 m/s
Distance to Coast: 28 km
Depth: 20m
Soil: Unconsolidated Sand
Weather Extremes: Extratropical Storms

6. Loads Waves Wind Design Situation h (m) T (s) λ (m) ω (rad/s) c (m/s)
Average Wave
1,00
5,55
48,09
1,13
8,67
1,28
ESS
8,40
10,50
172,13
0,60
16,39
3,01
Height
13,80 m
90,00 m
Design Situation
U ( m/s)
Gust (m/s)
U (m/s)
Start Up 3
Normal Operative
6,38
24,69
8,02
27,44
Shut Down 25
Extreme Sea State
23,97
29,58
26,63
32,97
Return- 50 years from ESS
33,56
41,41
37,48
46,42

7. Wind Force Calculus On the Rotor On the Tower NREL FAST-AeroDyn Soft
Operating Conditions
Stoped Rotor Conditions
On the Tower
NREL FAST-AeroDyn Soft

8. Waves Force Calculus Morison’s Equation Water Pressure
Inertia Coefficient Drag Coefficient
Water Pressure

9. Monopile Virtual Model

10. SeaFEM Analysis
Wave Amplitud: 8,4 m
Wave Period: 5,55 s

11. Dimensions

12. Materials Characteristics Ducorit ® D4 Compressive strength 210 MPa
Tension strength
10 MPa
Modulus of elasticity
70 GPa
Density
2.740
Poisson’s ratio
0.19
Static coefficient of friction (Grout-Steel)
0.6
Characteristics
Steel
Young’s Modulus
210 GPa
Poisson’s Modulus
0,3
Torsion Modulus
81 GPa
Maximal Stress
235,2 MPa
Specific Weight
N/m³

13. Boundary Conditions Foundation: Linear Soil Spring
Vertical Constrain at Pile’s Bottom Tip
Wind loads
Wave loads from SeaFEM
Self Weight
(kN)
X (m)
K (kN/m)
y (mm)
p (kN/m)
19.750,70 18
10,15
4.022,81

14. Maximal Stresses

15. Conclusions Objectives Accomplished Calculus Complexity
Feasible Construction
Necessary Informatic Tools
Considerations
Environmental Degradation
Economical Feasability
Protection Against Corrosion