This standard specifies the material, design criteria, manufacturing, and acceptance testing requirements for elastomeric bearings used in road bridges. It covers plain and laminated bearings, designed to accommodate loads, translations, and rotations between bridge superstructures and substructures.
Earlier specification for material, design, manufacturing, testing, and acceptance requirements for elastomeric bearings in bridges.
Quick Reference Values
Minimum ultimate tensile strength of elastomer17 MPa
Minimum elongation at break of elastomer400%
Hardness of elastomer50-70 IRHD or Shore A
Typical shear modulus (G)0.8 to 1.2 MPa
Maximum average compressive stress10 MPa
Maximum shear strain due to permanent loads0.5
Maximum shear strain due to total loads0.7
Key Formulas
S = (Length x Width) / [2 x (Length + Width) x Thickness] — Shape factor for a rectangular pad
Ec = 5 G S^2 — Apparent Young's modulus of elastomer in compression
σc = P / A ≤ 10 MPa — Permissible compressive stress
Practical Notes
This code has been largely superseded in practice by IRC: 83 Part II for highway bridge projects governed by MoRTH/NHAI.
The 'Shape Factor' is a critical parameter governing the bearing's load capacity and performance; it must be calculated correctly.
Ensure bearings are sourced from a reputable manufacturer with proper test certificates as the acceptance testing (Clause 7) is rigorous.