Sliding-friction isolators are the most promising among the developed isolation devices to achieve the desired performance of bridges during seismic events. These devices add flexibility to stiffer piers, dissipate undesirable input energy, and avoid possible concentration of ductility factor demand in piers. In this paper, an isolation system has been presented that is simple to manufacture and to easy implement in existing or new bridges. The proposed isolation system uses two-material flat sliding surface mounted on high-stiffness low-damping laminated rubber bearings in combination with low-stiffness high damping laminated rubber bearings to introduce predefined restoring force. The analysis results for an existing bridge are presented in this paper for recorded ground motions. The energy dissipation capacity of the system increases with sliding amplitude while maintaining the restoring force. It has been demonstrated that the proposed isolation system can be effectively used to enhance the seismic performance of bridges for wide range of intensity levels of expected ground motions. A simple procedure is also presented for the selection of isolation system parameters for desired performance requirements.
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