Shake-Table Tests on an Industrial Steel Rack Isolated with Innovative Modular Devices

This paper discusses the experimental results from dynamic shake-table tests conducted at the University of Pavia and at the EUCENTRE Foundation (Pavia, Italy) on an industrial steel rack seismically isolated with innovative devices. Despite the undeniable effectiveness of common isolators in reducing seismic demands on superstructures, their application to non-structural systems can be hindered by cost, durability, and mechanical issues. To overcome these drawbacks, an innovative isolator has been patented by Kyneprox S.r.l., based on a multiple articulated quadrilateral mechanism and named “Kinematic Steel Joint (KSJ)”. This device can be manufactured from steel sheets, possibly stainless or galvanized to mitigate corrosion issues. The KSJ imposes to the superstructure a pendulum-type motion with self-centering behavior, and its modular nature allows tailoring it to different masses. Friction within pinned joints grants some energy dissipation to the device, and replaceable fuses can be added to act as brakes before reaching the maximum displacement range. KSJ devices were installed at the base of a five-shelf, two-bay industrial steel rack, isolated in the cross-aisle direction and braced in the down-aisle one. Incremental uniaxial shake-table tests were conducted in the isolated direction under three different loading scenarios. The beneficial effects of the isolators on the dynamic response of the rack are demonstrated by the elastic response spectra of the input signal imposed to its base.