Hysteretic behavior of grouted connections in offshore wind turbine support structures

Abstract

Grouted connections (GCs) with shear keys have been widely applied in various offshore wind turbine support structures. The urgent energy demand in Eastern China makes building wind farms in offshore earthquake areas vital, however, the hysteretic behavior of the GCs has not been studied in depth. In this paper, three GC specimens were tested under different constant axial loads and cyclical horizontal forces. The different axial loads, i.e. the axial compression ratios were considered as the control parameter. The displacement ductility, energy dissipation capacity, and stiffness degradations of the specimens are discussed in detail. The results showed that an increasing axial compression ratio has detrimental effects on the hysteretic performance of GCs. It was also found, however, that all GC specimens exhibited favorable ductility and energy dissipation capacity, even the ones with high axial compression ratios. This indicates that GCs with shear keys are applicable for offshore support structures in seismic regions. Furthermore, finite element analyses in ABAQUS were conducted and compared with the experimental results. It was found that the numerical models could predict the hysteretic performance and crack propagation process of GCs. These models could be implemented in further parameter studies.