Structure calculations for Tripods

SKI Ingenieurgesellschaft performs nonlinear structural analyses for tripods on behalf of the company. The dimensions of the individual components are optimized under consideration of load capacity and fatigue strength. Further details can be found e.g. in the publication Stahlbau, Jahrgang 76, Issue 9.

The numerical model of the tripod foundation structure with concrete filling will be evaluated by a parameter study regarding fatigue strength and compared with an equivalent tripod foundation structure without concrete filling. The results of the structural analysis were compared with measured data. As a result, it was found that the ovalization of the pile-sleeve pipes was significantly reduced. 

This type of foundation for offshore structures can be used in water depths between 25 m and 50 m. The advantage of this construction, compared to monopiles, is that three piles are now used instead of one. This distributes the force over several piles and struts, which means that smaller diameters are required. This reduces the effort and material (wall thicknesses) during production, transport (diameter) and assembly (weight). Depending on water depth and ground conditions, the selected foundation structure can be adapted.

OWT - Tripod
View of the tripod foundation structure
Numerical volume model of the tripod foundation structure (diploma thesis D. Wagner)
Tripod of an offshore wind power plant

Our services

On the part of SKI Ingenieurgesellschaft the following services can be provided:

  • Local stress and fatigue calculations for tubular joints
  • Structural design under wind and wave load
  • Assessment of stress concentrations (hot spots)
  • Stress-optimized dimensioning of the central node
  • Comparative calculations for welding and cast nodes
  • Mode of action of weld finishing operations
  • Grout for modeling the pile-sleeve connections 
  • Pile-soil interaction

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