Experimental behavior of full-scale unbounded polyester-fiber reinforced rubber isolators for residential buildings

This paper presents the results of an investigation on full-scale innovative low-cost unbounded polyester-fiber reinforced high-damping elastomeric isolators (UPFREIs) to be used for seismic protection of residential buildings in Colombia, South America. In order to characterize the mechanical behavior of the UPFREIs, two full-scale prototypes were manufactured and tested at the Structures Laboratory of the Universidad del Valle. The experimental results were compared with results from the same test performed with two traditional connected steel reinforced isolators (SREIs). Both isolation systems were designed for a residential 5-story building with a target period of 2,5s located in a medium-high seismicity region. A dedicated set-up was designed and built specifically for the experimental tests. Results from shear tests up to 100% shear strain with sustained axial load exhibited very satisfactory behavior of the UPFREIs versus the SREIs with no residual deformation after unloading. An enhanced damping mechanism with damping ratio between 10 and 15 % was provided by the frictional fiber interface. Lower horizontal stiffness of the UPFREIs was obtained at higher deformation levels due to the typical rollover deformation. Despite the higher axial flexibility with respect to SREIs, UPFREIs also provided an adequate vertical to horizontal stiffness ratio. The results show that the developed UPFREIs have great potential to be implemented as a low-cost seismic isolation system of residential buildings.