Design and Calculus of the Foundation Structure of an

Offshore Monopile Wind Turbine

Author: Carlos Garcés GarcíaDirected by: Julio García Espinosa

ContentsIntroductionWind TurbineEmplacementLoadsGrout ConnectionTransition PieceMonopileFoundationLoads AnalysisConclusions

Monopile

A Monopile?Its Parts

The PileThe GroutThe Transition

PieceFunction

The Offshore Wind Turbine

Rating 5 MWRotor Orientation, Configuration Upwind, 3 BladesControl Variable Speed, Collective

PitchDrivetrain High Speed, Multiple-Stage

GearboxRotor 126 mHub Diameter 3 mHub Height 90 mCut-In, Rated, Cut-Out Wind Speed 3 m/s, 11.4 m/s, 25 m/sCut-In, Rated Rotor Speed 6.9 rpm, 12.1 rpmRated Tip Speed 80 m/sOverhang, Shaft Tilt, Precone 5 m, 5º, 2.5ºRotor Mass 110,000 kgCoordinate Location of Overall Center of Mass

(-0.2 m, 0.0 m, 64.0 m)

NREL 5MW Wind Turbine

EmplacementLocalisation: 39º 15’N, 74º

15’WAverage Wind Speed: 6,38 m/sDistance to Coast: 28 kmDepth: 20mSoil: Unconsolidated SandWeather Extremes:

Extratropical Storms

Loads

Waves

Wind Height 13,80 m 90,00 m

Design Situation U ( m/s)Gust (m/s) U (m/s)

Gust (m/s)

Start Up 3Normal Operative 6,38 24,69 8,02 27,44Shut Down 25Extreme Sea State 23,97 29,58 26,63 32,97Return- 50 years from ESS 33,56 41,41 37,48 46,42

Design Situation h (m) T (s) λ (m) ω (rad/s) c (m/s) a ()Average Wave 1,00 5,55 48,09 1,13 8,67 1,28ESS 8,40 10,50 172,13 0,60 16,39 3,01

Wind Force CalculusOn the Rotor

Operating Conditions

Stoped Rotor Conditions

On the Tower

NREL FAST-AeroDyn Soft

Waves Force CalculusMorison’s Equation

Inertia Coefficient Drag Coefficient

Water Pressure

Monopile Virtual Model

SeaFEM AnalysisWave Amplitud: 8,4 mWave Period: 5,55 s

Dimensions

MaterialsCharacteristics Ducorit ® D4Compressive strength 210 MPaTension strength 10 MPaModulus of elasticity 70 GPaDensity 2.740 Poisson’s ratio 0.19Static coefficient of friction (Grout-Steel)

0.6

Characteristics SteelYoung’s Modulus 210 GPaPoisson’s Modulus 0,3Torsion Modulus 81 GPaMaximal Stress 235,2 MPaSpecific Weight 76.900 N/m³

Boundary ConditionsFoundation: 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

ConclusionsObjectives AccomplishedCalculus ComplexityFeasible ConstructionNecessary Informatic Tools

ConsiderationsEnvironmental DegradationEconomical FeasabilityProtection Against Corrosion