Design and fatigue assessment of gravity base foundations for offshore wind turbines

Resumo

In this work, a gravity base foundation (GBF) was designed to support the DTU’s 10 MW wind turbine.
Recently, the industry is considering GBFs as a potential solution to the difficulties of driving monopile
foundations in certain types of soil. Also, checking their feasibility in greater water depths is a pivotal question
since these concrete structures might be cheaper than the steel monopile alternative. Thus, in a 40 meters water
depth, the proposed model is checked for its geotechnical capacity and the resistance of critical points under
extreme loads. The foundation is designed with a natural frequency that avoids excessive fatigue damage due to
the action of Brazilian environmental loads and rotor operation frequencies. This paper discusses the most
influential factors in these analyses. Palmgren-Miner rule assessed the fatigue damage in association with the
widely employed S-N curves for concrete. SIMA-RIFLEX’s dynamic analysis module generated the stress time
series. Rainflow method, combined with the Markov matrix, is utilized for counting stress cycles.