What is the maximum permissible sulfur and phosphorus content in the steel?

0.050% each (Clause 4), to prevent brittleness and ensure durability during tensioning.

Can high tensile steel bars used for prestressing be welded?

No, welding alters the microstructure and significantly degrades the high-tensile properties achieved during manufacturing.

What is the minimum elongation required for these bars?

A minimum of 6% elongation at rupture on a gauge length of 5.65 √A (Clause 6.2).

IS 2090

: 1983

Code of Practice for Design of Bearings for Bridges

SupersededSpecializedSpecificationStructural Engineering · Bridges and Bridge Engineering

Superseded by IS 2090:2018

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This standard lays down the requirements for the manufacture, supply, and testing of high tensile steel bars (plain and ribbed) intended for use in prestressed concrete. It strictly governs chemical composition and vital physical properties such as proof stress, minimum elongation, and long-term stress relaxation.

Provides earlier general guidelines and requirements for the design and selection of bridge bearings.

Quick Reference Values

Carbon content (max)0.90 %

Sulphur content (max)0.050 %

Phosphorus content (max)0.050 %

Minimum elongation at rupture6 %

0.2% Proof stress (min)80% of minimum ultimate tensile strength

Stress relaxation (max after 1000h)5% at 70% UTS initial stress

Practical Notes

High tensile steel bars must never be welded or subjected to localized heat on site, as this permanently destroys their required tensile properties.

Ensure proper storage strictly away from moisture to prevent surface corrosion; pitting acts as a stress concentrator leading to premature brittle failure.

The 1000-hour relaxation test is crucial for verifying the material's ability to maintain prestressing forces over the structural lifespan.