Active displacement control of a wind-exposed mast

The present paper describes the use of an active mass damper for the reduction of the wind-induced displacements of a full-scale mast built for the purpose at the University of Perugia (Italy). After a brief description of the mock-up structure and the bench tests carried out to characterize the active control device, the results of the tests and the numerical simulations performed to optimize the control gain parameters are displayed. The comparison between the results of the numerical simulations and those from the experimental tests highlighted the effects of the unavoidable imperfections of the physical system, such as the limitation of the available power, the presence of friction, the limited extension of the moveable masses' strokes and the computation time delays, that reduce the effectiveness of the control system. With the best gain parameters, several full-scale tests have been executed to observe the behaviour of the structure under wind loads. The comparison between the performance of the uncontrolled and the controlled structure clearly showed the effectiveness of the proposed technique for the reduction of both displacements and vibrations.