Influence of the gap size on the response of a single-degree-of-freedom vibro-impact system with two-sided constraints: Experimental tests and numerical modeling

The large displacements caused by strong earthquakes in base-isolated structures (buildings, bridges, strategic facilities, equipment, ⋯) can excessively deform or damage the isolation system lead to pounding with surrounding moat walls adjacent structures, if available seismic gap is not sufficient. acceleration spikes impact structure itself as well sensitive equipment housed it. A possible mitigation measure consists interposition of deformable shock absorbers (bumpers). In this paper, influence amplitude on experimental response a single-degree-of-freedom oscillator, excited harmonic base and symmetrically constrained two unilateral dissipative bumpers, investigated. parametric investigation considered both positive, null, negative gaps. Particular attention paid study effect, response, transition from positive small gaps excessive Secondary resonances low frequency range, associated occurrence multiple impacts, were experimentally observed for Finally, results reproduced, sufficiently accurate manner, using suitable numerical model, whose parameters identified based data.