Vibration control of seismic structures using semi-active friction multiple tuned mass dampers

An energy dissipation mechanism is an indispensable part of a tuned mass damper system, since it reduces the mass stroke of a system to a manageable level. Dry friction is a natural source of energy dissipation for tuned mass dampers. Nevertheless, there is no difference between a friction-type tuned mass damper and a dead mass added to the primary structure if static friction force inactivates the mass damper. To overcome this disadvantage, this paper proposes a novel semi-active friction-type multiple tuned mass damper (SAF-MTMD) for vibration control of seismic structures. Using variable friction mechanisms, the proposed SAF-MTMD system is able to keep all of its mass units activated in an earthquake with arbitrary intensity. A comparison with a system using passive friction-type multiple tuned mass dampers (PF-MTMDs) demonstrates that the SAF-MTMD effectively suppresses the seismic motion of a structural system, while substantially reducing the strokes of each mass unit, especially for a larger intensity earthquake. This means that applying the SAF-MTMD requires less installation space than a PF-MTMD system. The current study also shows that the SAF-MTMD performs well in a low-intensity earthquake, in which the PF-MTMD is inactivated due to friction.