A numerical investigation on grouted connections for offshore wind turbines under combined loads

Grouted connections have been widely used in offshore wind support structures to connect upper structures and lower foundations. Their mechanical behaviour is critical to the integrity of the entire support structure. In this study, numerical models were established and verified to investigate the stress distributions of grouted connections under combined compression and bending loads. It was found that the locations of shear keys had a significant influence on the maximum Mises stress in the steel tubes and Tresca stresses in the grout. The following parametric study of geometric configurations indicated that the thickness of a tube had a reverse relationship to the maximum stress. Meanwhile, the maximum Tresca stress was not sensitive to any geometric configurations, except grout thickness. Considering the gap between the detailed solid modelling and design process, based on beam modelling, a nominal average stress was computed over the compressed side of the steel tube within grouted connections. Consequently, stress correlation factors were obtained between the maximum Mises stress in a steel tube and the nominal average stress of a grouted connection. This method can be used in the preliminary design to evaluate the general behaviour of grouted connections under combined actions.