The space frame foundations are referred to jacket, tripod
and also four legged steel lattice structures, Figure 2 and 3.
They are most suitable for deep water especially jacket
structures can be up to 70m water depth and having a
structural dimension of 25x60m, Figure 6.
The space frame foundations can also refer to gravity tripod foundation as shown in Figure 4. It is used in transitional depth of 10-40 m, and consist of two heavy concrete structures connected by three legs, one structure sitting on the seabed while the other is above the water, cf. Tethys.
Floating structure foundations are used in deep depth applications (40-900 m) and consist of a balanced floating structure moored to the seabed with fixed cables. The floating structure may be stabilized using buoyancy, the mooring lines, or a ballast. The mooring lines may cause minor scouring or a potential for collision. Transmission lines also produce an electromagnetic field that may be harmful to some marine organisms, cf. Tethys.
Figure 5: Floating structure foundation Source: Tethys.
During the last 24 years since 1990, wind turbines have increased significantly in size and performance with only a small increase in the weight of the wind turbine components. This means that the structural system becomes more flexible and thus more sensitive to dynamic excitations at low frequencies. Thus, the dynamic response of wind turbines is affected by the properties of the foundation and the subsoil, cf. [14.00].
