Structural Optimization of Offshore Wind Turbine Towers under Stochastic Environmental Loads Integrating Finite Element Modelling and Reliability Analysis

Resumo

Based on national and international reports related the wind energy, it is evident that the Brazilian wind power sector is expected to experience exponential growth in the coming years. In this context, the structural optimization of offshore wind turbine towers emerges as a viable approach to reducing the costs associated with the commissioning of offshore wind farms currently waiting environmental licensing by IBAMA. Offshore wind towers are subjected to continuous loads resulting from wind and ocean actions. Frequently, design codes and technical literature treat these loads as deterministic, neglecting the inherently stochastic nature of such phenomena. Therefore, this research work proposes an analysis methodology for the structural optimization of offshore wind turbine towers through the integration of the Finite Element Method (FEM) and reliability analysis, aiming to contribute to the development of the wind energy sector in Brazil. Initially, a finite element model associated to a 5MW steel monopile offshore wind turbine (OWT) with 77.6m high was developed taking into account the effect of the soil-structure interaction, the non-deterministic dynamic behaviour of the wind and ocean loadings, and the aerodynamic forces related to the rotor. The proposed analysis methodology aims to establish an optimization framework that combines FEM and reliability analysis, incorporating the intrinsic uncertainties involved in the modelling of offshore wind turbine towers.