Operational Modal Analysis and Finite-Element Model Updating of Pilot Concrete Wind Turbine Tower

Abstract

This article deals with the dynamic behavior of a reinforced and posttensioned concrete structure for applications in wind turbine towers. Measurements were performed using triaxial accelerometers in a 30 m high tower model, and the experimental setup is described in detail. The natural frequencies and mode shapes of the structure were extracted using operational modal analysis (OMA). The structure’s Young’s modulus was calculated analytically from the natural frequency of the radial-circumferential bending mode and their values were compared with the results obtained in static tests conducted on a concrete bar. The dynamic stiffness was calculated based on the frequency of the bending mode. Soil–foundation–structure interaction is reported in this article by calculating the displacement produced in the foundation and tower structure using data from the first tower bending mode. A simplified finite-element model was created to study the influence of elasticity and stiffness parameters on the modal shape of the structure and validate the results obtained from the experimental data.