IMPORTANCE OF FOUNDATION DESIGN
• HIGH COST OF THE FOUNDATION ( NEARLY 25%-35% OF OVERALL COST )• NATURAL FREQUENCIES OF THESE STRUCTURES ARE VERY CLOSE TO THE
FORCING FREQUENCIES OF THE WIND, WAVE, ROTOR FREQUENCY AND BLADE SHADOW FREQUENCY.
FOUNDATION DIFFERENCES OIL & GAS PLATFORM VS WIND
TURBINESRELATIVELY STIFF RELATIVELY FLEXIBLESTRUCTURAL DYNAMICS NOT CRITICAL STRUCTURAL DYNAMICS VERY CRITICALWAVE LOAD DOMINANT WAVE AND WIND LOAD BOTH IMPORTANTSTRAIGHT FORWARD RELATION FORCE-RESPONSECOMPLEX, UNCORRELATED LOADING‘PROTOTYPE’ GENERALLY LARGE NUMBERS
DESIGN CRITERIA & CONSIDERATIONS
• LOADS: MAGNITUDE OF THE PERMANENT LOAD OF THE PLATFORM WIND / WAVE / CURRENT
RATIO VERTICAL / HORIZONTAL LOADS QUASI STATIC / CYCLIC
• WATER DEPTH• SEA FLOOR
SOIL TYPECURRENT -> SCOURING
• FABRICATION, TRANSPORTATION & INSTALLATION AVAILABLE CONSTRUCTION SITES / EQUIPMENT
GRAVITY FOUNDATIONS
• LOADING SITUATION VERY DIFFERENT FROM PILED FOUNDATION• SUBSTANTIAL VERTICAL LOADING REQUIRED ( STABILITY)• GENERALLY IMPRACTICAL SUPPORT STRUCTURE FOR WIND
TURBINES IN RELATIVELY SHALLOW WATER
PILED FOUNDATIONS• FLEXIBILITY / ADAPTABILITY :
SOIL CONDITIONSWATER DEPTHSCOURDIAMETER AND WALL THICKNESSTENSION & COMPRESSIONPENETRATION AND NUMBERTRACK RECORD / EXPERIENCEDIFFERENT INSTALLATION METHODS
CHOICE OF FOUNDATION TYPE• LOADS WIND / WAVE / CURRENT
HORIZONTAL AND VERTICALQUASI STATIC / CYCLIC
• WATER DEPTH• SOIL CONDITIONS• STORAGE REQUIREMENTS• TRANSPORTATION / INSTALLATION EQUIPMENT REQUIREMENTS• AVAILABLE CONSTRUCTION SITES / EQUIPMENT• ECONOMICS
THINK ABOUT ????????Depth of
water column
Mass needing Support
Turning and bending forces on structure
Location specific issues
Seabed geology and soils
Scour and sediment
movementEnvironmental impact
Construction
requirement
Installation requiremen
tCAPEX OPEX Materials
CURRENT & FUTURE PROTOTYPES
• CURRENT FOUNDATION TYPES INCLUDES FOUNDATIONS CURRENTLY AVAILABLE TO OFFSHORE WIND
DEVELOPERS• FUTURE PROTOTYPES
INCLUDES FLOATING AND DEEPWATER CONCEPTS
FOUNDATIONS USED ON UTILITY-SCALE OFFSHORE WIND PROJECTS TODAY:
•Mono pile
•Gravity foundation
•Tripod foundation
FLOATING CONCEPTS:
WHILE SEVERAL FLOATING OFFSHORE WIND CONCEPTS EXIST, TWO DESIGNS ARE THE BEST KNOWN:
• HYWIND• WINDFLOAT
HYWIND WINDFLOAT
ANALYSIS TO BE DONE :Prelimin
ary Sizing
Stability
Load Case
Structural
Design
DESIGN LOAD CASES:
• POWER PRODUCTION FAULT• PARKED FAULT• ADDITIONAL CASES• ULTIMATE STRENGTH LOAD CONVERGENCE• FATIGUE LOAD CONVERGENCE
DESIGN IN SHORTSt
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THANK YOU
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