Experimental dynamic response of a SDOF oscillator constrained by two symmetrically arranged deformable and dissipative bumpers under harmonic base excitatio

During strong earthquakes, base isolated systems (buildings, bridges, strategic facilities, equipment, etc.) can impact against the surrounding moat wall because of the deformation of the isolator if the available separation distance is limited. A possible mitigation measure is the interposition of shock absorbers. The aim of this work is to illustrate some of the results of an experimental laboratory campaign concerning the study of the dynamic response of a single-degree-of-freedom (SDOF) oscillator excited by a harmonic base acceleration and symmetrically constrained by two unilateral deformable and dissipative constraints (bumpers). Three different peak values of table acceleration, four amplitudes of the total gap between mass and bumpers, and four types of bumpers were considered. Among the various aspects investigated, particular attention was paid to the study of pseudo-resonance curves of maximum absolute acceleration and excursion of the SDOF oscillator and to the characterization of the hysteresis zone.