Construction Materials | Seismic Isolator for Buildings
The Structure of Seismic Isolating Rubber Bearing
New Structure Technology - "Seismic Base Isolation System", proven during large-scale earth tremors
The Seismic Isolating Rubber Bearing consists of alternating laminations of thin rubber layers and steel plates (shims), bonded together to provide vertical rigidity and horizontal flexibility.
Vertical rigidity assures the isolator will support the weight of the structure, while horizontal flexibility converts destructive horizontal shaking into gentle movement.
Special Characteristics of Bridgestone MRB
- Cover rubber
- the outer cover protects rubber laminations against ultraviolet rays and ozone exposure that deteriorate rubber.
- Bonding
- through a proprietary surface treatment prior to vulcanization, the individual rubber layers and steel shim plates are permanently bonded together between the upper and lower flanges.
Principle of Laminated Rubber Bearing
A standard rubber block can be easily compressed and sheared because of its biaxial softness. A laminated rubber bearing can be easily sheared, but its high vertical stiffness allows it to support a heavy structure such as a building.
| Rubber block | Laminated rubber bearing (LRB) | Comparison of compressive and horizontal shear features |
|---|---|---|
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Catalogues (Characteristics data of Bridgestone's seismic isolation bearings)
Bridgestone offers several types of rubber bearing and handle a wide rage of sizes from small to large diameters.
Seismic isolation product line-up
(Updated on October, 2022 / 7.5MB) 
For details, please contact the local dealers in your area or Head office.
Line-Up
HDR | High Damping Rubber Bearing
[Certifications(Minister of Land, Infrastructure and Transportation)] MVBR-0468(X0.4R)、MVBR-0430(X0.6R)
Rubber bearing that uses high damping rubber; where the rubber material itself demonstrates spring and damping capability. Generally, separate damper is not required; good for space-constraint installation.
Since its hysteresis curves are relatively smooth, seismic isolation effect can also be expected for in-building precision equipments, etc., rather than for buildings only.
Rubber material has two different kinds of elastic modulus(refer red as E0.4, X0.6R), it's also applicable to light column load.
LRB | Lead Rubber Bearing
[Certifications(Minister of Land, Infrastructure and Transportation)] MVBR-0447
Rubber bearing that has a lead plug embedded at the centre of laminated natural rubber; where the"laminated natural rubber" demonstrates spring capability, while the "lead plug" demonstrates damping capability.
Generally, separate damper is not required; good for space-constraint installation. It shows
hysteresis of elasto-plastic characteristics, and it is possible to fine adjust the attenuation setting by varying the lead plug diameter.
Only one kind of rubber material is used.(referred as G0.40).
NRB | Natural Rubber Bearing
[Certifications(Minister of Land, Infrastructure and Transportation)] MVBR-0295(N3.G3.G5),MVBR-0446(G4)
Rubber bearing that uses natural rubber. It has low damping performance (about 2~3% at
equivalent damping factor), excellent linearity, and stable restoring force characteristic.
Separate damper is required, but with combination of damper types, attenuation, etc., it
is possible to design with greater flexibility.
Rubber material has four different kinds of elastic modulus(referred as G0.30,G0.35,G0.40, G0.45), able to support wide range of column loads.
Elastic Sliding Bearing
[Certifications(Minister of Land, Infrastructure and Transportation)] MVBR-0349(SL series),MVBR-0469(SP series),MVBR-0479(SK series)
It is consist of 2 pieces: 1) a natural rubber bearing bonded with PTFE(Teflon) material and 2) a stainless steel slide plate. Small displacements are absorbed by the rubber itself, while large displacements cause the rubber bearing to slide on the plate.
Since the restoring function will be lost when the sliding occur r ed, normally it is used in combination with NRB, LRB or HDR.
There are three different type offriction coefficient, which type to be used is based on necessity of damping.