Interação solo-estrutura não linear em fundações de aerogeradores onshore em radier estaqueado: efeitos na análise modal e dinâmica em um aerogerador NREL 5 MW

Abstract

Wind turbine support structures are usually dynamically sensible. With the rotor diameter rise, in order to increase energy production, this situation tends to get more critical, giving rise to the needing of more accurate studies regarding the dynamic behaviour of the system. It is known that, due to previous researches and design practice, soil-structure interaction (SSI) plays a major role in the wind turbine natural frequencies of vibration, as well as in the stresses and displacements when applying dynamic operational and wind loads. Considering this scenario, the present research seeks to study non-linear soil-structure interaction models for analysing wind turbine towers. It was used a wind turbine model from National Research Laboratory (NREL) with nominal power capacity of 5 MW and geotechnical data from the Wind Power Plant Miassaba 3, located in the Rio Grande do Norte State, Brazil. Four different SSI models were used: an analytic model with the expressions from DNV (2002); a non-linear numerical FEM model (ABAQUS) using p-y, t-z and Q-z load transfer curves from API (2003); a nonlinear numerical FEM model (ABAQUS) calibrated with pile load test from Miassaba’s construction site and a non-linear FEM model (ABAQUS) with elasto-plastic constitutive model (Mohr-Coulomb failure criteria) also calibrated with the same pile load tests. The results show a discrepancy between analytical and numerical models, where the former provides larger values of global foundation stiffness, the differences being more critical for extreme load case scenarios. This fact brings attention towards to the needing of non-linear models for the dynamic behaviour assessment, in order to archive more reliable foundation design. Additionally, the effects of SSI were evaluated in term of dynamic amplificatory factor of 1P load (FEM model of the wind turbine developed in SAP 2000), which revealed a 16% and 20% foundation load increasing, respectively, in overturning moment and horizontal force.