Some Applications of Passive and Semi-active Control Devices for Harmonic Vibrations Damping in Cable-Stayed Bridges

Abstract

Long-span bridges can undergo vibrations during both construction and service phases, due to their flexibility and lightness. Moreover, they can be sensitive to environmental dynamic actions. The internal damping of this kind of structures is moderate, therefore vibration damping is frequently obtained by using dedicated devices, as an example tuned mass dampers (TMD). On the other hand, TMD’s performance strongly depends on their constitutive parameters and on the external loads. In this paper the adaptive use of a new electro-mechanical damper (EMD) is presented, made of an oscillating mass around the axis of an alternator, whose output is connected to a resistor: in this way the kinetic energy of the oscillating pendulum is transformed into electrical energy dissipated. An application is made of this EMD to a cable-stayed bridge steel model. The internal parameters of this new damper are constant or variable according to a semi-active control law. The experiments show that the adaptive semi-active control strategy makes effectiveness of this EMD independent on the excitation characteristics.