J1010403 Vibration Characteristics of Base Isolation System with Change of Load

We made a small base isolation system using friction bearings made of SUS304, that used for heavy structures. Characteristics of this system with change of loading based on vibration experiments were investigated. Increasing the loading on this system, a natural frequency and damping ratio indicated increase. Especially in case using only friction bearings with a marble plate, the damping ratio became conditions of over damping. A peak amplitude ratio divided the response by the input also was increased. And a friction coefficient was measured by a static loading test, it was increased depending on the load. Results from numerical analyses using parameters estimated by experiments, the peak response amplitude increasing the friction coefficient do not change in case that the natural frequency is fixed. However the response was amplified by resonance in case that the natural frequency increases with the load. It is important to fix the natural frequency.