Components, systems and materials › Bridge components › Elastomeric bearing
Elastomeric bearing
What it is
An elastomeric bearing is a block of rubber with bonded steel plates between a bridge deck and its pier or abutment, allowing rotation and horizontal movement while carrying vertical load.
Where it is used
Short and medium span road and rail bridges, flyovers and buildings needing movement or isolation.
How it works
The steel plates restrain the rubber from bulging, so vertical stiffness is high, while shear deformation of the rubber layers allows the deck to expand, contract and rotate. Larger shear strain means larger movement capacity.
Types
- Plain pads
- laminated bearings
- bearings with PTFE sliding surfaces
- lead-rubber isolation bearings
Materials
Natural rubber or chloroprene, steel reinforcing plates, sometimes PTFE and stainless steel sliding surfaces.
Design checks compressive stress, shear strain, rotation, stability and slip under the specified loads and temperature range. Plan size, number of layers and plate thickness are chosen accordingly. Bearings are tested for stiffness and quality before installation.
Installation and QA steps
- Prepare a level pedestal with correct levels.
- Place bearings at correct orientation.
- Seat the deck without twist.
- Check gaps and shear strain.
- Inspect periodically.
- Excessive shear from incorrect installation
- bulging and cracking of rubber
- walking out of position
- bearings seated on uneven pedestals
Codes cited
- IRC:83 (Parts I to IV) (India): Road bridge bearings: metallic, elastomeric, pot and spherical types by part.
- EN 1337 (series) (Europe): Structural bearings.
Cited by number only. We do not reproduce code text, tables or figures.
Related
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