Dynamic analysis for the installation of offshore wind turbine foundations

Abstract

This report looks into the possibility for using modified phased out shuttle tankers to install jacket foundations for offshore wind turbines. New massive wind mill farms are now being planned out in water depths of 40 meters and beyond, making the transition from monopoles to jacket type foundations inevitable. The similarity between these new foundations and the much larger jackets used on oil platforms, makes it natural to look into if the already well established technology can be applied to these foundations as well. A thorough dynamic analysis is carried out by the use of the computer program MOSES. Included in the analysis is a time domain analysis which will be compared to third party analyses. Further investigations of the non-linear behaviour are made to test the possibility for normalizing into a frequency domain solution. Also, based on these results, ways to reduce the dynamic amplification factors are examined. The main aspects are the lifting methods, the dynamic hook loads and the sea state limitations during installation.