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IS 12891:2018 is the Indian Standard (BIS) for elastomeric bearings for bridges - specification. This standard specifies the requirements for materials, design, manufacturing, testing, supply, and installation of elastomeric bearings. These bearings are used for accommodating translations and rotations in bridges and other structures.
Specifies material, design, manufacturing, testing, and acceptance requirements for elastomeric bearings used in bridges.
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Bridges and Bridge Engineering
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Ensure strict adherence to installation tolerances, especially levelness and alignment, as improper installation is a major cause of premature bearing failure.
! The bond between elastomer and steel laminates is critical. Visual inspection for delamination and the adhesion strength test (Clause 9.5) are crucial for quality assurance.
! The design and material selection must account for the specific temperature range, seismic zone, and exposure conditions of the bridge site.
EN 1337-3:2005CEN (European Committee for Standardization), Europe
HighCurrent
Structural bearings - Part 3: Elastomeric bearings
Specifies requirements for the design and manufacture of elastomeric bearings for bridges and structures.
AASHTO M 251-06 (2021)AASHTO (American Association of State Highway and Transportation Officials), USA
HighCurrent
Standard Specification for Plain and Laminated Elastomeric Bridge Bearings
Covers material requirements and design for plain and laminated elastomeric bridge bearings.
AS 5100.4:2017Standards Australia, Australia
MediumCurrent
Bridge design - Part 4: Bearings and deck joints
Covers design, material, and installation of bearings, including elastomeric types, within a broader bridge design code.
BS 5400-9.1:1983BSI (British Standards Institution), UK
HighWithdrawn
Steel, concrete and composite bridges. Bridge bearings. Code of practice for design of bridge bearings
Provided design rules and specifications for bridge bearings, including elastomeric types, now replaced by Eurocodes.
Key Differences
≠IS 12891 specifies a shear modulus (G) range of 0.8 to 1.2 MPa, whereas EN 1337-3 defines five distinct classes of G-value (from 0.70 to 1.35 MPa), allowing for more specific design choices.
≠The maximum allowable average compressive stress in IS 12891 is generally limited to 10 MPa (for G=0.9 MPa). EN 1337-3 and AASHTO LRFD often permit higher design compressive stresses, sometimes up to 15-17 MPa, depending on the bearing type and shape factor.
≠Ozone resistance testing in IS 12891 requires exposure to 50 pphm concentration for 96 hours at 40°C, while AASHTO M 251 specifies a more stringent test at 100 pphm for 100 hours at 40°C.
≠IS 12891 combines design and material specifications into a single document, similar to AASHTO M 251. In contrast, the European system splits this into multiple parts (e.g., EN 1337-1 for general rules, EN 1337-3 for elastomeric bearings, EN 1337-10 for inspection).
Key Similarities
≈All standards are based on the same fundamental construction of alternating layers of elastomer (like Natural Rubber or Neoprene) vulcanized and bonded to internal steel laminates.
≈The concept of the 'Shape Factor' (S), defined as the ratio of the loaded area to the force-free area, is a critical and universally used parameter in IS 12891, EN 1337-3, and AASHTO M 251 for determining compressive stiffness and load capacity.
≈All standards require the bearings to perform the same primary functions: support vertical loads, accommodate horizontal translations (shear), and allow for rotations of the bridge deck.
≈The core set of required material property tests for the elastomer is very similar across the standards, including tensile strength, elongation at break, hardness, compression set, and shear modulus.
Parameter Comparison
Parameter
IS Value
International
Source
Shear Modulus (G)
0.8 - 1.2 MPa (specified range for design)
Five classes: 0.70, 0.85, 1.00, 1.15, 1.35 MPa
EN 1337-3:2005
Ultimate Tensile Strength (Min)
15 MPa
≥ 15.5 MPa (2250 psi)
AASHTO M 251-06
Elongation at Break (Min, for Natural Rubber)
≥ 400%
≥ 400%
EN 1337-3:2005
Maximum Design Shear Strain (γq)
0.7
0.7 (for steel laminated bearings)
EN 1337-3:2005
Ozone Test Concentration
50 pphm
100 pphm
AASHTO M 251-06
Hardness (Shore A)
60 ± 5
50, 60, or 70 (± 5)
AASHTO M 251-06
Internal Steel Plate Thickness (Min)
3 mm
2.67 mm (0.105 in)
AASHTO M 251-06
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Elastomer Hardness (Shore A)55 ± 5
Minimum Tensile Strength (MPa)17
Minimum Ultimate Elongation (%)400
Maximum Compression Set (24h @ 70°C) (%)35
Design Shear Strain Limit0.7
Maximum average compressive stress (MPa)10
Key Formulas
S = (L * W) / (2 * ti * (L + W)) — Shape factor for rectangular bearing
σc = F / (A) ≤ 10 MPa — Check for average compressive stress
γs = Vs / Tr ≤ 0.7 — Check for shear strain
Tables & Referenced Sections
Key Tables
Table 1 - Physical Properties of Elastomer
Table 2 - Dimensional Tolerances for Bearings
Table 3 - Acceptance Criteria for Short Duration Compression Test
Table 4 - Acceptance Criteria for Shear Modulus Test