Products
Foundations
BARD Engineering GmbH has developed a brand new type of foundations for water depths between 25 and 40 m for its offshore
wind farms. We have given it the name, ‘Tripile’ – a three-legged
model of steel pipes bearing an angular supporting cross-piece.
The ‘Tripile’ support structure is lighter and less expensive than all other offshore WEC foundations utilized previously. Compared to other offshore foundations, its individual parts are much more compact. They are easy to manufacture at any dock or steel mill, and easy to install by means of conventional jack-up platforms provided by maritime technologies worldwide.
The ‘Tripile’ foundation for ‘BARD 5.0’ is extremely flexible and has been patented. To ensure that each foundation can ideally match its respective location, the piles are variable in length and strength against wind forces. We use three types of piles in ‘BARD Offshore 1’ wind farm depending on the soil conditions and water depths within the 59 km2 wind farm area. The strongest piles are more than 80 m long and penetrate up to 30 m into the seabed of the North Sea.
Since the pile diameter is only around 3 m, we can use pile driver rams which have already been successfully used for the so-called ‘Monopiles’, for example, for 2 – 3 MW offshore wind turbines. Such ‘Monopiles’ can not be used for 5 MW wind turbines on towers that are from 80 to 100 m high and at water depths of more than 20 m. They would be about 7 m wide and would weigh 1,000 t. Such foundations could only be lifted by means of special cranes, and could not be rammed into the ground using the technology of today.
Before ramming starts, our ‘Tripiles’ are aligned using a guiding frame, so that they are arranged at an exactly defined distance from each other. In their final position, their upper edge is some metres above the water
surface. The guiding frame is removed, and a supporting cross-piece is
mounted on the three piles. The supporting cross-piece is made of a central cylinder, connected to the tower, and three inclined supports. These
braces hold the connection cylinder to the three piles in the water and
carry landing platforms for service vessels.
The supporting cross-piece and braces are welded together as flat steel elements. Such structures can be produced with small tolerances and can be easily reinforced at positions of greater stress. They are easier to manufacture as compared to ‘Tripod’ foundations, popular nowadays, which complex, pyramid-shaped structure of connected circular pipes requires high-precision production, is time consuming and economically not viable.
The connections between the supporting cross-piece and the three
piles in the water are grouted by means of specific concrete. This
connection provides an even distribution of forces from the supporting cross-piece to the piles in BARD ‘Tripiles’. Consistent technical
processes make installation work easier for fitters.
The supporting cross-piece weighs approx. 490 t. Just one heavylifting crane mounted on the special jack-up vessel is required for all
assembly work, and is also used to lift tower segments and turbines.
This provides for short installation period; a complete BARD offshore WEC
can be erected in less than two days!
We are convinced that our ‘BARD 5.0’ ‘Tripiles’ are the only ideal solution for WECs at water depths up to 45 m.