Fluid inertia damper using MR fluid with a long spiral bypass pipe

抄録

An inertia damper with a long spiral bypass pipe was developed in order to obtain a series inertia effects for vibration suppression of structures in practical use. The damper comprised a cylinder, piston, and MR fluid. The gap was spirally formed around the outside of a cylinder, and acted as a long bypass pipe. MR fluid is well known for its changeable damping effect, but the mass of the fluid is the focus of this study. It is obvious from previous studies that a fluid inertia effect is caused by quick motion in the long bypass pipe, and it depends on the length of the bypass pipe, compression ratio of area, and density. A large inertia effect can be derived if the fluid has a heavy mass. In order to confirm the inertia effect, a prototype damper was manufactured, and resisting force characteristics were measured. Seismic response tests using a 3-story structure were then performed using a shaking table with the damper installed. Each story of the structure had a height of 3 m, and a weight of 6 tons with a total height of 9 m and a total weight of 18 tons. Several types of earthquakes were input, and the response acceleration, relative displacement, and reaction force were measured. Finally the effects of vibration reduction were confirmed experimentally, and a feasibility study was discussed.