Abstract

Lever-type active multiple tuned mass dampers (LT-AMTMD) consisting of several lever-type active tuned mass damper (LT-ATMD) units with a uniform distribution of natural frequencies have been proposed here for the vibration control of long-span bridges under the excitation directly acting on the structure, rather than through the base. The main purpose of selecting this form of excitation is to present guidelines for the buffeting control design of long-span bridges under wind loads. Estimations have been made on the performance of the LT-AMTMD with identical stiffness and damping coeficient and unequal masses for the reduction of harmonically forced vibrations by resorting to the defined evaluation criteria. The LT-AMTMD with the actuator set at the mass block is found to have better effectiveness and higher robustness in alleviating the vibrations of structures in comparison with the LT-AMTMD with the actuator set at any other location. A new major result is that both the spring static and dynamic stretching of the LT-AMTMD with the actuator set at the mass block may be freely adjusted in accordance with the practical requirements by changing the support locations within the viable range while practically maintaining the same performance. Numerical results demonstrate that the LT-AMTMD with the actuator set at the mass block can highly improve the performance of the LT-MTMD (that is, the passive counterpart of the LT-AMTMD) and provide better effectiveness than a single LT-ATMD. Estimations have also been simultaneously carried out on the LT-AMTMD (a single LT-ATMD) with respect to the hanging-type AMTMD (a single hanging-type ATMD) as well as on the LT-MTMD (a single LT-TMD) with reference to the hanging-type MTMD (a single hanging-type TMD), so as to highlight the improved performance of the proposed control system.

Keywords

damping, mass dampers, vibration control, harmonically forced vibrations, lever-type active multiple tuned mass dampers (LT-AMTMD), static and dynamic stretching of the spring, long-span bridges

Authors