Natural Rubber bearing generally consists or interleaving layers of rubber bonded sandwich fashion to steel plates. The whole unit is covered with rubber to afford weather protection.
A bridge basically consists of bridge deck supported by piers. In order to avoid over stressing and damage by movements of vehicle and loading to the piers, bridge bearings are used to accommodate these movements so as to reduce the reaction forces and bending movement to within the safety limits of structure. Natural Rubber is an ideal engineering material for bridge bearings as it is highly elastic and suffciently soft to accommodate these movements without transmittiing harmful stees and also it can absorb and isolate energies from impacts and vibrations.
Types of bearings
- Laminated bearings - an elastomeric bearing containing steel laminates bonded to rubber
- Plain pad bearing - a plain rubber pad containing no steel plates
- Strip bearing - a plain pad bearing for which the length is much greater than the width ( > 10 times)
- Pot bearing - a bearing consisting essentially of a block of solid rubber enclosed between a mettal piston and metal cylinder