A Stress Evaluation Method for Grouted Connections of Offshore Wind Turbines

[Introduction] Grouted connections are widely used to connect the support structure and the foundation of offshore wind turbines. Therefore, their mechanical properties are very important to the reliability of the whole structure. In order to find a proper method to evaluate the stresses of grouted connections, numerical simulations were conducted. [Method] Numerical models were established to investigate the stress distribution of a grouted connection under given compression and bending loads. The conceptions of nominal average stress and stress correlation coefficient were then proposed, which were used to evaluate the overall stress level of the grouted connection. Moreover, parameter studies were carried out, and the range of stress correlation coefficients were determined. [Result] It was found that both the Mises stresses of steel tubes and Tresca stresses of the grout were dominated by the locations of shear keys in the grouted connection. And there was an inverse negative correlation between the thickness of steel pipes and the maximum stresses of them. At the same time, the maximum Tresca stresses of the grout were only sensitive to the change of its thickness rather than the change of the thickness of steel tubes. Finally, the stress correlation coefficients all fell between 3 to 6 according to the parametric studies. [Conclusion] The result of parametric studies can partly guide the preliminary designs of grouted connection, and the stress correlation coefficients can be used to approximately evaluate the mechanical properties of grouted connections under combined loads.