- O I L E S / Isolation System Introduction -

Square Base Isolators Made of Multilayer Natural Rubber with an internal Lead Plug

Performance is maintained during repeated strong earthquakes, providing good durability and reliability

Advantages

	LRB can satisfy the requirements for stable performance of bearings by supporting loads and allowing elongation and rotation of girders over a long period of time.
	Customized dispersion ratio of horizontal force during an earthquake can facilitate simpler bridge design.
	Maintenance is easier compared with steel bearings.
	LRB can be designed according to the size and characteristics of the structure as vibration damping and habitability (trigger) functions can be determined by adjusting the size of the lead plug.

Structure

LRB is an isolation system which combines multilayer rubber construction with lead plugs; the former bears the load and isolates vibration, and the latter absorbs energy as a damper.

Function

Multilayer rubber isolator Function

1)	Load supporting / Rotation Absorbing function Rubber reinforced with steel plates provides stable support for structures Multilayer construction provides better vertical rigidity than single layer rubber pads for supporting a building.

2)	Horizontal elasticity function (prolonged oscillation period) Earthquake vibration is converted to low speed motion As horizontal stiffness of the multi-layer rubber bearing is low, strong earthquake vibration is alleviated and the oscillation period of the building is increased.

Horizontal elasticity / prolonged oscillation period

3)	Restoration function Horizontal elasticity returns the building to its original position. After an earthquake the restoring force of the rubber layers returns the building to the original position.

Function of lead plug (damper)

4)	Vibration damping function It absorbs large vibration of the structure As the layers of rubber are distorted, the lead plug is plastically deformed, which absorbs the earthquake energy and quickly damps the vibration.

Vibration damping and Displacement restriction

5)	Trigger function Reduces vibration from sources other than earthquake. Vibration generated by strong winds are avoided as the relative rigidity of the lead plug restricts the flexibility of the isolation system until the plug is subjected to a certain level of force.