This paper describes a novel approach to efficiently simulate the structural dynamics of a concrete Gravity Based Foundation (GBF). In this time-domain analysis, the GBF is subjected to loads applied by the turbine, wave loads and the influence of the soil structure interaction is taken into account. Wind turbine loads are computed using the aeroelastic software FAST and expressed at the connection point between the turbine and the GBF Wave loads on the GBF are computed using a potential, nonlinear wave model. Nonlinear soil-structure interaction is modelled with the use of a macro-element specifically developed for shallow foundations. Finally, the structure itself is modelled using an Euler-Bernoulli multifiber beam, which allows representing the reinforced concrete sections.
It is shown that the numerical model is able to efficiently simulate the behaviour of a GBF foundation under nonlinear irregular wave forces and loads transmitted by the turbine. It reproduces nonlinear phenomena such as a decrease in material stiffness due to damage and permanent strains but also the GBF displacements considering soil structure interaction.