Design of shaking table tests for resilient structures with fiber-reinforced elastomeric isolators

Base isolation is a proven earthquake-resistant solution, but the high cost of conventional isolation units has limited its application to developed countries and generally only to high-importance buildings. Recent earthquakes demonstrated that the higher vulnerability of buildings in less developed countries may result in disproportionate fatalities compared to developed countries. In the last decades there have been research efforts to drastically reduce the cost of seismic isolation and make it affordable for ordinary structures. In this context, fiber-reinforced elastomeric isolators (FREIs) turned out to be a promising option to reduce both the cost and weight of rubber bearings by replacing the steel shims used in conventional bearings with fiber mesh fabric. In previous studies, the authors investigated the behaviour of FREIs through both numerical analyses and experimental programs in a number of configurations including different geometries, rubber matrices and fabrics. A reclaimed rubber compound for FREIs has also been recently developed to further reduce their cost and environmental impact. The project ERIES-FREISUST (Fiber-Reinforced Elastomeric Isolators for seismic resilient structures with SUSTainable Solutions) aims to provide a paradigm shift in base isolation design with FREIs, demonstrating the combined reliability of the novel base-isolation system (i.e. lateral stability and re- centering capacity, as well as adequate vertical stiffness and load-bearing capacity under different loading conditions) and its potential in reducing damage to nonstructural components and contents through 3D shaking table tests. Two systems will be investigated with different standardization and cost level, namely a Virgin- rubber Carbon-fiber FREI (VC-FREI) and a Reclaimed-rubber Polyester-fiber FREI (RP-FREI). VC-FREI and RP-FREI will be installed at the base of a full-scale reinforced concrete frame prototype and tested at the ST3D shaking table facility of Laboratorio Nacional de Engenharia Civil (LNEC), Lisbon, Portugal. This paper presents the design and preliminary numerical investigations of the base isolation systems addressing the main novelty and the research objectives of the project.