Transient Monotonic and Cyclic Load Effects on Mono Bucket Foundations

Today, 80 % of all European offshore wind turbines are installed on monopiles. A cost-effective alternative to the monopile is the mono bucket foundation. For an offshore wind turbine foundation in open seas, the dominant load is often coming from waves.

During storms, large waves are formed and when hitting the foundation they induce high impact loads with a short duration. It is important that the foundation is able to resists these huge loads. Fortunately, the conducted research showed that the capacity of the mono bucket foundation is high to impact loads. When exposed to a huge wave load the foundation is sucked to the seabed, creating extra capacity during the impact.

Over the life-time of an offshore wind turbine foundation will be hit by millions of waves. Each wave might lead to a permanent rotation of the foundation. Therefore, it is important to be able to estimate the total deformation accumulating for each wave impact. The presented research has shown indications that only the first waves contribute to the permanent rotation. These indications are seen in small-scale laboratory tests and on a full-scale mono bucket foundation.