The main aim of the thesis is to develop and test some design tools for the design of offshore wind turbines (OWT) resting on direct foundations on the seabed. As will be made clear in subsequent sections structural design of OWT is a complex problem and the integration of geotechnical design within the broader structural design problem can take many different forms. It is not yet clear what degree of integration of geotechnical and structural design is optimal, as the experience so far is limited and no clear consensus has yet emerged on the particular. Our objective is not to settle this issue proposing a closed methodology but rather to describe different tools that can be employed within different design approaches.