A macro-element model for multidirectional cyclic lateral loading of monopiles in clay

This paper investigates numerically the impact of multidirectional cyclic loads on the response of a monopile in clay supporting an offshore wind turbine (OWT). The results indicate that multidirectional loading modifies the foundation stiffness and hysteretic damping, which affects the OWT eigenfrequencies and damping. Based on these results, a macro-element model to represent the monopile response in the time-domain integrated load simulations employed in OWT design is proposed and verified against finite element analyses (FEA). The verification indicates the macro-element can simulate the monopile response with almost the same accuracy as FEA, but with a considerable reduction in computational effort.