Presentations

Abstract

Alternatives to monopile foundation for offshore such as jackets have challenges for an economical design and manufacturing speed/capacity due to its unfavourable welded joints. The reason for this is that the complex welds in the joint region reduce the fatigue resistance of structural joints of circular hollow sections with factors that results in increased wall thicknesses of the tubes and overspending of steel in the multi-membered part of the jacket of approximately 80%. If the fatigue resistance for these joints can be increased, the wall thicknesses of the legs (chords) and brace members can be reduced resulting in significant lighter structures. If the complex joints can be prefabricated the production rate of the jackets structures can significantly increase. TU Delft and Tree Composites, together with their partners, are researching the behavior the wrapped composite joint to solve these challenge for lattice type welded structures. In March 2023, the first ever full scale testing of Composite joints took place at the facility of OCAS, Belgium. The CRONOS test Bench was used to perform accelerated fatigue testing. This abstract presents major steps of testing the results and conclusions. The tests showed that the fatigue resistance of the composite joint outperforms the welded connection and even surpasses the fatigue strength of unwelded steel. This performance open the path to unprecedented designs and optimization of support structures for offshore wind.