In regard to the sustainability of future cities, an increase in sustainable energy sources needs to be managed. Therefore, the German government decided on increasing the ratio of green energy up to 20% by 2020. In accordance with this, offshore wind energy parks will be constructed, as they provide the advantage of lasting air cleanliness and preserving natural resources. To ensure construction safety, wind energy mills are constructed using ductile steels of large thickness. Here, an application of high-strength steels provides the possibility of reducing the amount of material while construction safety is still ensured. Considering the long life cycle of wind energy mills’ foundation structures and the recyclability of the steel grades used, their construction becomes a relevant factor in reducing CO2 emissions. Furthermore, the use of less material reduces CO2 emissions. Due to existing safety concepts, however, the application of high-strength steels is only conditionally allowed. Thus, the current study concerns the development of a safety concept based on the existing concepts to allow the application of high-strength steels. Furthermore, as the structural steel parts need to be joined, an energy-efficient welding process is utilised: electron beam welding. The structural steel parts and weld joints are investigated with respect to their mechanical properties by analysing their loadability in combination with safety concepts. The load on the material is evaluated to ensure construction safety. In addition to the investigation of safety requirements, the supplied mechanical properties are investigated. As the weld joints show different properties from the base material, the joints are considered the critical part. The joints are investigated concerning strength and toughness. Afterwards the mechanical properties are correlated with the wind energy structures. The prevention of failure is fulfilled when the mechanical properties of the weld joints exceed the required mechanical properties.