Round 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 Wide range of bearing capacity (about 100 - 2000 tons/unit) Bearings can be designed according to the size and characteristics of the building as vibration damping and habitability (trigger) functions can be determined by adjusting the size of the lead plug. Integration of the rubber bearing and a lead plug can save installation space and provide a functional isolation system. 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. Basic Features This chart shows the relationship between force and displacement when LRB is subjected to extreme deformation as would be expected in a major earthquake. Design values concur closely with physical measurements of performance, demonstrating high accuracy of the design method. Characteristic restoring force of LRB are shown by two lines (bi-linear model). This characteristic makes structural modelling relatively simple. * LRB series can conform more precisely than the result shown in the chart. Contact OILES for more information. Function Multilayer rubber isolator 1) Load supporting 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. 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. Lead plug (damper) 4) Vibration damping function It absorbs large vibration of the building. As the layers of rubber are distorted, the lead plug is plastically deformed, which absorbs the earthquake energy and quickly damps the vibration. 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.