Influence of Friction in the Seismic Behaviour of HDRB+SD Isolation Systems

The response of an isolation system made of HDRBs and SDs under low energy earthquakes, classified on the basis of the energy at the basement, is analyzed. The study pointed out that for very low values of the energy, measured by means of the Arias intensity, the isolation system was not put in action, and the superstucture behaved like a fixed base one. The behaviour has been correlated to the ratio between the inertial force resultant and the maximum friction forces of the slider devices. For higher values of the energy, instead, the isolation system was activated and a value of the Arias intensity was individualized, which separates the two behaviours. The variability of the first resonance frequencies with the input energy has been particularly analyzed, as well as the structural response in terms of maximum accelerations, maximum displacements and relative horizontal displacements in the building.