Design of Grouted Connections in Offshore Wind Turbines

At the widely-used grouted connection for monopile founded offshore wind turbines unexpected settlements have been detected. These findings have led to a withdrawal of the mostly applied design code for grouted connections. Without having a valid design guide and under the impression of failing connections alternative designs had to be developed. A review of existing codes shows remarkable differences in the assessment of the capacity of grouted connections. Based on extensive and advanced finite element analyses the structural behaviour of grouted connections is investigated. It becomes obvious that the existing codes can not directly be used for the design of grouted connections for monopile founded offshore wind turbines. Furthermore, a plane cylindrical connection is not appropriate. Cylindrical connections with shear keys or conical connection are alternatives. Approaches for the structural verification of theses types are presented.