EXPERIMENTAL AND NUMERICAL ANALYSIS OF A PIECEWISE NONLINEAR-LINEAR STIFFNESS ISOLATOR UNDER SEISMIC LOADS

This study illustrates the positive outcomes of employing a tri-dimensional HSLDS isolator as opposed to linear isolators in reducing vibrations transmitted to the suspended mass during near-fault earthquakes. A model with lumped parameters is described, incorporating a piecewise nonlinear-linear stiffness. Initial tests are carried out with a harmonic base motion assumption to assess the isolator's transmissibility. A good agreement is observed when comparing the model with the experimental measurements. Further, the isolator's performance is evaluated experimentally considering simulated earthquakes. The results are presented through vertical acceleration time histories and spectra, highlighting the reduction in vibrations obtained by using the nonlinear isolator.