Zur Bemessung von Monopiles für zyklische Lasten

Monopiles have already been used as foundations for a large number of offshore wind energy converters. They may also be suitable for the wind farms planned in German Sea regions. However, the monopile diameters will then be larger than 5 m. For such diameters no experience exists regarding the design and especially the design with respect to cyclic loads. In the paper a design method is presented in which cyclic triaxial tests and a numerical model are combined in order to predict the accumulated displacements to be expected over the lifetime of the foundation. It is shown that the requirement of rigid clamping under design load, which is often discussed in practice, is not a suitable measure to ensure good performance under cyclic loads. Finally, for a practical example the displacement increase to be expected over the lifetime of the foundation is quantified.