The authors have developed a new simple tuned mass damper (TMD) system, which can be applied to buildings with different natural periods in horizontal two directions. In this paper, the principle of the tuning mechanism and a simple method for determining the parameters of the system is shown, and the superiority of the control performance to that of a conventional TMD is demonstrated by resonance curves and seismic response analyses. In addition, shaking table tests using a 1/10 scaled specimen are conducted, then its dynamic performance and an accurate trace using a simple analytical model are confirmed.
