Experimental and numerical investigation of a vertical vibration isolator for seismic applications

Abstract In near-fault seismic zones, the vertical acceleration experienced during a strong event can be greater than horizontal acceleration. Methods to reduce are applied in various forms and common use. However, methods acceleration, practical protection systems for these applications, remain elusive. One strategy protect structures, which has been demonstrated effective situations where excitation is horizontal, isolate structure. For excitations, this difficult due need maintain sufficient stiffness strength direction of gravitational loads. The high gravity loading while allowing flexibility isolation earthquakes led research on use High-Static-Low-Dynamic Stiffness Systems (HSLDSS) particular Quasi-Zero (QZSS), have zero equivalent equilibrium position. Although effective, QZSS sensitive mistuning prone large deformations relatively small increments static load building applications. This paper presents results an analytical experimental study HSLDSS system carrying payload subject base using sinusoidal as well actual, scaled earthquake signals. Static tests also presented. consists rigid rotating arms, springs damper. By suitable selection parameters could serve QZSS. Results show that both significantly magnification force transmission retains at numerical model includes friction solved direct integration equation motion. Experimental from scale agree theoretical predictions.