What are the three main types of pot bearings defined in this code?

Fixed pot bearing (allows rotation only), free sliding pot bearing (allows rotation and multi-directional movement), and guided sliding pot bearing (allows rotation and movement in one direction). (Clause 3)

What is the primary material for the elastomeric pad inside a pot bearing?

The elastomer shall be of natural or synthetic rubber (polychloroprene), meeting the properties specified in Table 2.

What is the mandatory vertical load test for a pot bearing?

The bearing must be subjected to a vertical test load of 1.5 times the design vertical load. There should be no signs of damage or leakage. (Clause 6.2)

What is the maximum permissible coefficient of friction for PTFE sliding surfaces?

The coefficient of friction, when tested as per the specified procedure, shall not exceed 0.05. (Clause 6.3)

IS 12892

: 1990

Pot Bearings for Bridges - Specification

SupersededSpecializedSpecificationBIMStructural Engineering · Bridges and Bridge Engineering

Superseded by IS 12892:2018

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This standard specifies the requirements for the materials, design, fabrication, testing, and installation of pot bearings for use in bridges. It covers fixed, uni-directionally free, and multi-directionally free sliding pot bearings designed to transfer large vertical loads while accommodating rotation and, where applicable, translational movements.

Earlier specification for material, design, manufacturing, testing, and acceptance requirements for pot bearings in bridges.

Quick Reference Values

Maximum coefficient of friction (PTFE)0.05

Vertical test load1.5 x Design vertical load

Horizontal test load (for guided bearings)0.15 x Design vertical load

Proof stress for steel plates240 MPa (Min)

Hardness of elastomer pad55 +/- 5 IRHD

Practical Notes

While this IS code exists, bridge bearing design and supply in India is now predominantly governed by IRC:83 (Part 2) and MoRTH specifications, which are more comprehensive and updated.

The internal sealing rings are a critical component prone to failure if not manufactured and installed correctly. Their failure leads to elastomer extrusion and loss of bearing function.

Installation tolerances and procedures are paramount. Incorrect seating, leveling, or misalignment of bearings can induce unintended stresses and lead to premature failure of the bearing or the structure.