Study on Isolation Device for Decrease of Displacement by Using Control of Friction

This paper deals with reduction of horizontal relative displacement by using a frictional force for a seismic isolator. First, a compression spring is attached to the base. Next, a slope plate is superimposed on it. The frictional force acts on the slope plate. The restoring-force is given to the seismic isolator by the compression spring attached to the base. In the equation of motion of the analytical model, the frictional force changes in proportion to the displacement. The restoring-force is also proportional to the displacement. The restoring-force always works in the direction of the center. Therefore, the frictional force and the restoring-force are both proportional to the displacement. Simulation analysis was performed under various conditions using this analysis model. As a result of conducting the analysis and an experiment with this model, it was shown that response acceleration and relative displacement can be reduced successfully. In order to reduce response acceleration and relative displacement more, analysis was carried out with the actual earthquake waves under the conditions to change the coefficient of friction by relative displacement. As a result, the coefficient of friction that reduces relative displacement most effectively without impairing the performance of the seismic isolator was established. However, the coefficient of friction that reduces the response acceleration and relative displacement effectively depends on by seismic waves. Therefore, in this report, the coefficient of friction that reduces response acceleration and relative displacement most effectively is determined by using white noise. It is analyzed with actual seismic waves by using the decided parameters. The performance of the seismic isolator is examined.