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Gravity Tripod

"A new asset class in offshore wind"

The Gravity Tripod is a component based structure that benefits from the best aspects of other foundation concepts. It is a hydro-dynamically transparent structure which doesn’t require piling, is manufactured from low cost tubular sections in a rapid assembly process and is installed with minimal seabed intervention. The two components of the Gravity Tripod act together to ensure that the structure has an extremely long design life and is insensitive to turbine loads; the structure is able to accommodate turbines from 3 to 16MWs over a 100 year period. In addition the structure has a low bearing pressure on the seabed and so is capable of accommodating a wider range of sediment types, with less seabed preparation, than other gravity-base designs.

  • Gravity Tripod
  • Gravity Tripod
  • Gravity Tripod
Gravity Tripod

The transition piece resolves all turbine loads efficiently, through the use of gravitational mass above the water column (and so offsetting the "buoyant penalty" of other gravity-base designs). This mass is accommodated in ballast tanks within the transition piece and may be installed after the structure has been deployed. Through placing the mass of the structure above the waterline, the design minimises hydrodynamic loads by keeping teh submerged volume to a minimum (and reduces the total material required by avoiding the buoyant effect of having mass below the waterline.)

The hydrodynamically transparent concrete jacket structure, facilitated by the use of the multiple column design, ensures that the foundation experiences low wave impact and current drag forces. Because the forces are lower than for other gravity base designs, the bearing pressure on the seabed is lower. In this way the structure is able to be installed on a wider range of seabed sediment and geology types and the level of seabed preparation required is minimised. The low profile of the base slab ensures minimal scour of the seabed the risk of which may be further reduced through the integration of concrete mattresses to the final structure. At the same time the multiple column design allows the use of low cost pre-stressed concrete columns and facilitiates a rapid onshore assembly process, alowing high supply rates and reducing offshore construction times.

Gravity Tripod

The Hyperboloid Jacket is manufactured from spun-cast, pre-stressed tubular sections, manufactured in an efficient mass production process at the final assembly site or at feeder locations. Similarly, other sub-components may be pre-manufactured in a just-in-time supply chain and stored prior to assembly, the high density storage of sub-components ensures that the manufacturing sites do not have excessive spatial requirements, meaning that the final assembly may be accommodated in a wider range of port locations - siting production close to your wind farm.

The tubular sections and base components are post-tensioned together. Due to the precast nature of the base plate, the structure is able to be moved almost immediately after the final pour, ensuring a high productivity rate and benefitting the wind-farm developer in lower unit cost and reduced construction periods.