Ultimate load transfer characteristics of a typical grouted connection used in the monopile foundations of offshore wind turbines

Monopile foundations, which are thick steel pipes buried deep in soil, are connected to the transition piece through grout. Grout connections, which play a key role in load transfer, have many reports of contact and material failure. It should be noted that such failure reduces the structural capacity, which can be a risk to the economics of the offshore wind farm. Shear keys are attached to tubular steels and the capacity of the grout is obtained through complex load transfer characteristics. However, it is not known how the size of the shear key has an effect on the load transfer characteristics under the ultimate load. This study deals with the parametric structural analysis of the shear key size of the offshore wind grouted connection of the monopile for the ultimate load. The impact of shear key height for load transfer characteristics of grouted connection was presented as diverse aspects. The compressive stress, tensile stress, and contact pressure according to the size of the shear key were analyzed for the grout material and the interface, and how the presence of the shear key affects the stress was analyzed. In addition, various symmetries present in the grouted connections were discovered.