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

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

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

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)

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

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

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

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

Monopile Virtual Model

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

Dimensions

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 76.900 N/m³

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 1.944.000 10,15 4.022,81

Maximal Stresses

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