The 14 th World Conference on Earthquake Engineering October 12-17, 2008, Beijing, China A NOVEL ELASTOMERIC BASE ISOLATION SYSTEM FOR SEISMIC MITIGATION OF LOW-RISE BUILDINGS H. Toopchi-Nezhad 1 , M. J. Tait 2 , and R. G. Drysdale 3 1 Ph.D. Candidate, Dept. of Civil Engineering , McMaster University, Hamilton, Canada 2 Assistant Professor, Dept. of Civil Engineering , McMaster University, Hamilton, Canada 3 Professor Emeritus, Dept. of Civil Engineering , McMaster University, Hamilton, Canada Email: toopchh@mcmaster.ca , taitm@mcmaster.ca , drysdale@mcmaster.ca ABSTRACT : An innovative base isolation system for seismic mitigation of ordinary low-rise buildings is introduced in this paper. The proposed base isolation system utilizes “Stable Unbonded Fiber Reinforced Elastomeric Isolator” (SU-FREI) bearings. The steel plates used in conventional laminated rubber bearings are replaced with fiber fabric in FREI bearings. The fiber fabric is extensible in tension and has no flexural rigidity. In an unbonded application, the FREI bearings are simply placed between the superstructure and substructure with no bonding between the contact surfaces. Results from an experimental study conducted on model scale prototype SU-FREI bearings comprised of unfilled soft Neoprene rubber as the elastomer and bi-directional carbon fiber fabric as the reinforcement show that these bearings exhibit Stable Rollover (SR) deformation and perform as an effective seismic isolation device. The experimentally evaluated lateral load-displacement properties of the proposed SU-FREI bearings have been modeled using an iterative analysis with a simplified mathematical model. Results of time history analysis performed on both a 2-storey prototype base-isolated structure and a corresponding fixed-base structure indicate that the proposed base isolation technique can be employed efficiently in hazard mitigation of low-rise buildings located in high seismic regions worldwide. KEYWORDS: seismic isolation, unbonded application, stable rollover, fiber reinforced elastomeric isolators, low-rise building, masonry structure, laminated rubber bearings