Work Package 4 & 5

WP 4 - Integrated dynamic analyses of OWT

The soil interaction model 3Dsoil will be implemented in the IFE's time domain aero-hydro-elastic code, 3DFloat. This code performs integrated analysis of the offshore wind turbines, including modeling of the sea, sea loads, wind loads, fixed and floating structures, and mooring.

3DFloat is currently used by research, educational, and engineering organizations. It has been validated against other codes for offshore wind turbines with Spar-Buoy, Space-Frame, and Semi-Submersible substructures. It has also been validated against wave-tank tests of Spar-Buoy, Tension-Leg-Buoy (TLB), and semisubmersible platforms.

3DFloat is fundamentally formulated for highly nonlinear effects and is therefore well suited for advanced soil-structure modeling.

With the soil interaction models in place, their effectiveness will be evaluated by studying the sensitivity of foundation behavior on structural response and loads for typical OWT designs.

In addition, the driving design parameters will be explored for governing load cases reflecting both ULS and FLS cases.

WP 5 - Model calibration and verification

Responsible partner: NGI, Participating partners: IFE.

This WP involves both the calibration of the soil interaction models and their final verification. The study will be carried out on two levels: 1) foundation analyses without structural integration, and 2) analyses with fully integrated structural model.

The first level will ensure efficient calibration and will make it possible to focus solely on the soil interaction models. It is also suitable for comparison with model testing which is commonly carried out without any structure.

The second level of testing will involve a progressive improvement of the soil-foundation models through integrated analysis in 3DFloat. The response of the complete soil-structure model will in addition be evaluated against full scale measurement data, for instance those from Sheringham Shoal, and model test data, such as those performed by the project's external collaborators.