Design of Offshore moNopiles Including Seismic Interaction with Soil (DONISIS)

The renewable energy sector is rapidly expanding worldwide, with offshore wind playing an increasingly prominent role. After over two decades of European developments, the offshore wind industry is expanding to America and into the Asia-Pacific (APAC) region. Wind farm developers are currently facing the challenge of designing and building earthquake-resistant support structures for offshore wind turbines (OWTs), which requires reliable seismic analysis of the whole structural system and the soil.

DONISIS, a recent research project led by Delft University of Technology and set up in collaboration with the Carbon Trust’s Offshore Wind Accelerator (OWA) programme, will enhance the fundamental understanding of seismic soil-structure interaction mechanisms in tall, monopile-founded OWTs.

In the common case of bottom-fixed OWTs founded on large/stiff monopile (MP) foundations, serious challenges are introduced by the complexity of non-linear MP-soil interaction, which may be accompanied by dynamic amplification phenomena, permanent soil deformations and, possibly, ground liquefaction. Notwithstanding the advances in the field of earthquake geotechnical engineering, several gaps must be filled for the optimisation of OWT support structures, to avoid over-conservatism in designing and, consequently, overusing steel for fabrication. Such overuse would be unsustainable from a resource perspective and may prevent economic exploitation of offshore wind energy in seismic regions. The DONISIS research will put emphasis on the role of non-linear soil behaviour and pore water pressure effects in seismic soil-structure interaction.

The knowledge acquired throughout the research programme will feed into the development of a new one-dimensional seismic design model for monopile foundations, which will retain high accuracy while allowing fast design computations and swift research-to-practice transition in collaboration with the engaged industry partners. The goal is to develop a set of OWT seismic design recommendations and best practice guidelines for seismic monopile design.

Project end date:

2027

Project lead:

TU Delft, Netherlands

Partners:

TU Delft, ETH Zurich, NTNU, NGI, Bentley Systems/Plaxis, DNV, EDFR, SSE Renewables, Orsted, Nippon Steel Engineering, Penta Ocean, RWE, Siemens Gamesa Renewable Energy, TEPCO Renewables, Shell, TotalEnergies, Van Oord + certification bodies group of independent advisors: DNV, Bureau Veritas, NCREEE Taiwan