An experimental study of WECS tower dynamics

A first step in a study of the dynamic behaviour of a structure is to obtain the vibration mode shapes at the significant natural frequencies. The case of a single-level guyed tower with a large mass at the top such as is found in wind energy converters is studied experimentally to determine the natural modes of vibration using a 1.9 m high latticed steel model on a shaking table. The results indicate how the natural frequencies are influenced by the magnitude of the top mass, the initial guy tension and the condition of the fixity at the base of the tower. The appearance of a low-frequency torsional mode and the secondary excitation of lower modes due to coupled structural members at a higher frequency are of special interest. © 1986.