This study presents the concept of a multi-functional Tuned Mass Damper (TMD) using piezocomposite element as damping component. This new type of TMD intends to exploit the unused energy produced by the traffic-induced vibrations of the bridge structure for the generation of electric power while fulfilling its natural role of reducing undesirable vibrations in the structure. Since the proposed TMD is still in a development stage, this paper summarizes the concept underlying the mechanism of the TMD.