Preliminary Numerical Analysis of the Response of Base-Isolated SDOF Systems Constrained by Two Deformable Devices Under Seismic Excitations

Seismic isolation is a passive control methodology widely used for the mitigation of the dynamic response of structures. However, significant seismic actions can induce considerable displacements in these structures, which in turn can cause damage to the isolation system or impacts against adjacent structures in the event of insufficient seismic gap. A technique to prevent the occurrence of these negative phenomena can be obtained by interposing dissipative and deformable devices, called bumpers between the structure and the adjacent ones. Therefore, in this work the response, from a numerical point of view, of single-degree-of-freedom, SDOF, system isolated at the base subjected to known seismic actions and whose displacements are limited by bumpers has been studied. The system was designed according to an optimality relationship that relates the mechanical parameters of the isolator with those of the bumper, and is independent of the gap. The SDOF system investigated is representative of a typical base-isolated structure, therefore, the system exhibits a damping ratio ξ = 10% and a system natural period Tn = 3.00s. The dynamic response of the system obtained by impact with an appropriately designed bumper is compared with the response of the same system obtained without the impact and with an impact whit rigid bumper. Finally, the influence of the stiffness of the bumper, designed with the optimality relationship, and the gap is evaluated. The results show a considerable reduction in displacements compared to a modest increase in accelerations with respect to the no-impact condition, evidence that highlights the effectiveness of the optimality relationship used.