Combination of external loads

The project objective was to improve and consequently optimise the basis for design of offshore wind turbines. This was done through mapping of wind, wave, ice and current, by correlations of these, and by clarifying how these external conditions transform into loads. A method for derivation of combined partial safety factor for wind and waves was set up. Principles of synthesizing load cases and trends in wind speed series were clarified and stated. A forecast model for growth, drift and break-up of sea ice was found. A database was set up containing wind, wave and ice data used in the project. Finally a simple design procedure for offshore wind turbine foundations was developed. The model covers extreme loads, maximum operational loads and extreme ice load combined with associated operational loads. It was outlined how to derive relevant partial coefficients, advantages of a quadratic composition rule compared with a linear load composition was described, how dynamic interaction between wind and wave loads can be covered in predictions