Dynamic range implications for the effectiveness of semi-active tuned mass dampers

Abstract

The response of tall buildings subjected to dynamic wind loads has been widely studied. For excitations approaching the resonant frequencies of the structure, ensuring serviceability is a significant concern. One traditional solution is the implementation of a tuned mass damper (TMD), which acts as a passive damping device in the region of the tuned frequency. However, TMDs exhibit a limited bandwidth and often require a significant mass. Active systems, such as the active mass driver, have been utilized to improve the effectiveness of the TMD concept, but these systems require significant power and bring the inherent risk of instability. Hybrid semi-active schemes with variable damping devices have been proposed. They are stable, require low power, and are controllable, thus providing a broader range of applicability. The concept of a semi-active tuned mass damper (STMD) has been investigated, but the influence of the dynamic range of the semi-active damping device has not been documented. This analysis assesses the effectiveness of STMD systems using a variable-orifice damper and a magnetorheological damper with varying dynamic ranges. Results demonstrate a performance dependence on the dynamic range and also elucidate the superiority of non-linear damping devices. It is shown that the prescribed TMD mass may be reduced by a factor of two when semi-active control is implemented, thereby making the STMD an attractive and feasible option when space and weight concerns govern design.