Base isolation is one of the effective passive control methods, which can reduce earthquake responses of structures. In this paper, two base isolation systems are suggested for bridge. The one consists of PTFE(poly-tetra-flour-ethylene) friction bearing as damping devices and LRB(laminated rubber bearing)as restoring force devices. On the other hand, the other is composed of PTFE friction bearing and rubber annuli as restoring force devices. Using the system, the natural period and the damping of the base isolated bridge increase, so that the seismic response may reduce significantly.
A series of laboratory tests have been conducted on PTFE friction bearing, and LRB, and two suggested isolation system to determine the dynamic characteristics of the isolation system. It has been found that the friction coeffcient increases as velscity increases, while it decreases as pressure increases. The damping and the natural period of the bridge structure may be effectively moderated to the desired values using the suggested base isolation system.
