Analysis of the behaviour of seismic isolated structure on bearings connected to the structure with a dry friction damper.

The paper discusses systems with seismic isolation in which the seismic support part consists of an elastic element and friction one connected in series. The friction element is modeled with a dry friction damper. Only the elastic element works in the system at small vibrations, and at peak loads, slippage occurs in the dry friction damper. In this case, the load on the superstructure and the substructure is limited by the friction force in the dry friction damper. The harmonic oscillations of the considered system have been analyzed. At the same time, three possible modes of system behavior have been established. The first mode with a weak impact far from resonance is characterized by a purely elastic isolator behavior. The second, more dangerous mode is characterized by large plastic deformations at the initial impact stage. Still, after several cycles of plastic vibrations, the system adapts to the seismic impact and vibrates elastically. In this case, a progressive collapse of the system is possible at the first stage of loading. Finally, the third mode is characterized by plastic deformations at the initial stage of loading and during steady-state vibrations. In this case, progressive collapse at the first stage and low-cycle fatigue at the second stage of the system operation are possible. The necessary values of the friction force and damping in the system, excluding dangerous resonant vibrations, is to be more than 10% of the structure weight. [ABSTRACT FROM AUTHOR]