Investigating the use of Targeted-Energy-Transfer devices for stay-cable vibration mitigation

Free vibrations of a taut cable with an attached passive Targeted-Energy-Transfer (TET) device are investigated using an analytical formulation of the complex generalized eigenvalue problem. This problem is of considerable practical interest in the context of stay-cable vibration suppression in bridges, induced by wind, rain–wind and parametric excitation. The TET device is a nonlinear apparatus, which has been investigated and successfully ap- plied to the vibration suppression in several structural or mechanical systems. This study proposes, for the first time, the use of the TET device as a simple passive apparatus for stay-cable vibration mitigation. In this applica- tion, the device was modelled as a dashpot with a viscous damper in parallel with a power-law nonlinear elastic spring element and a lumped mass restrained to one end. The ‘flexibility of the support’ (imperfect anchorage to the deck) was also simulated by placing an elastic support (linear elastic spring) in series between the dashpot and the deck. The study derives a new family of ‘universal design curves’ for the TET device, by accounting for the effects of nonlinear elastic stiffness, lumped mass and flexibility of the support. To verify the adequacy of the universal curves and to evaluate the effectiveness of the TET devices, parametric numerical simulations were per- formed on a reference stay cable. As an application example, analytical results were employed to design the dampers of one flexible stay, installed on an existing cable-stayed bridge. In all the investigations, theoretical and numerical results were obtained and compared.