Inertia Mass Damper and its Application

Abstract

From early times adding auxiliary mass to the main mass has been done to mitigate vibration events. And much research of the structure by adding an equivalent mass using fluid or functional fluid has been done. On the other hand, the research and development of a new damper using rotating inertia mass began in the early 1970s in Japan. The new type damper was termed the “Mechanical Snubber” when it was used for piping and equipment systems in nuclear power plants. Tens of thousands of Mechanical Snubbers are used in Japanese domestic light water reactor and also in foreign countries. As one of the only surviving developers, the author would like to report the development process. This Mechanical Snubber has a large equivalent inertia mass and it accords with the design criteria of high stiffness of seismic method of nuclear power plant. In recent years, in the field of civil engineering and construction, studies using rotating inertia mass or negative stiffness of mechanism have come into favor. These studies are expected to be applied in structure and bridge engineering. This paper describes the historical background of inertia mass dampers, the theory of the inertia mass damper (I.M.D.) applied as a product, and the electromagnetic inertia mass damper (E.I.M.D.) developed as a passive and/or semi-active damper. Some experimental studies using shaking table in the National Center for Research on Earthquake Engineering (NCREE) in Taiwan and theoretical studies are introduced.