Abstract Summary
This paper presents an optimal design of a passive-adaptive Pendulum-Tuned Mass Damper (PTMD) to mitigate the structural vibrations of Offshore Wind Turbine (OWT) with a flexi-ble monopile foundation considering the Pile-Soil Interaction (PSI). The OWT basis on the 5-MW baseline proposed by the National Renewable Energy Lab (NREL). The PSI is de-signed by a pile modeled as beam-column elements supported by nonlinear springs for lat-eral loads (p-y curves) and axial loads (t-z and Q-z curves), applied at the nodal points be-tween the elements. The estimation of wind and wave spectra, as well as the hydrodynamic and aerodynamic loads, are conducted by using an in-house built MATLAB® routine working together with an ANSYS® 3-D finite element (FE) global model for evaluating the resultant peak displacement response at the OWT hub by a power spectral density (PSD) analysis. Op-timum design cases of PTMD parameters are obtained by a Genetic Algorithm (GA) optimi-zation minimizing the structural response of the tower. A static analysis procedure evaluates the monopile displacements and stresses over the foundation, then the stresses along the pile and the structural responses of the tower are evaluated in function of the wind velocity at the hub.
