IS 1785 (Part 2) : 2000plain hard-drawn steel wire for prestressed concrete, Part 2: As the drawn wire

IS 1785 Part 2:2000 is the **specification for plain hard-drawn steel wire for prestressed concrete — *as-drawn* wire (cold-drawn, not stress-relieved). It is the companion to IS 1785 Part 1 (stress-relieved wire); the two are distinct, non-interchangeable conditions**, and selecting the right one is a structural decision.

It sits in the prestressing stack:

• IS 1343 — prestressed concrete design · IS 1785 Part 1 — *stress-relieved* PSC wire (the usual structural choice)
• IS 6003 — indented PSC wire · IS 14268 — 7-ply strand · IS 10790 Part 1 — sampling

The single most important fact is the condition difference from Part 1:

• As-drawn (this Part) — cold-drawn to strength but not stress-relieved: it has higher relaxation, and a different ductility / stress-strain response than stress-relieved wire
• Stress-relieved (Part 1) — the heat-treated condition with the lower, more predictable relaxation that modern prestressed design generally assumes
• The IS 1343 loss calculation and member behaviour depend on the assumed wire condition — Part 1 and Part 2 cannot be swapped without re-checking the prestress loss

The engineering point: as-drawn wire is a defined product with a legitimate scope, but for general prestressed structural design the stress-relieved Part 1 condition is what is normally specified and assumed, precisely because of its better relaxation behaviour. Using Part 2 as-drawn where Part 1 was designed inflates long-term prestress loss beyond the design allowance — a quiet under-prestressing of the structure.

Scenario: prestressing wire procurement for a PSC member designed to IS 1343.

Step 1 — read the assumed condition: the IS 1343 loss/behaviour calc assumes a specific wire condition — for general prestressed design this is normally stress-relieved (Part 1).

Step 2 — specify the matching part: if the design assumed stress-relieved, specify IS 1785 Part 1 — do not accept Part 2 (as-drawn) as 'equivalent prestressing wire'.

Step 3 — if as-drawn is genuinely intended: ensure the higher relaxation of Part 2 was the value used in the IS 1343 loss calculation.

Step 4 — verify by test: sample per IS 10790 Part 1; not coil-tag acceptance.

Step 5 — handle: notch/corrosion protection as for all prestressing steel.

The condition must match the design's relaxation assumption — Part 1 and Part 2 are not the same product.

1. Supplying Part 2 (as-drawn) where Part 1 (stress-relieved) was designed. Higher relaxation than allowed → under-prestressed structure; the parts are not interchangeable.

2. Assuming 'hard-drawn PSC wire' is one product. Condition (as-drawn vs stress-relieved) materially changes relaxation/behaviour.

3. Relaxation not matched in the loss calc. If as-drawn is used, its higher relaxation must be the value in the IS 1343 calculation.

4. Coil-tag acceptance. Sample/test per IS 10790 Part 1.

5. Nicks/corrosion. Acutely sensitive at working stress — protect absolutely.

• IS 1785 Part 1 — stress-relieved PSC wire (the usual structural choice) · IS 1343 — PSC design
• IS 6003 — indented PSC wire · IS 14268 — 7-ply strand · IS 6006 — stress-relieved strand
• IS 10790 Part 1 — sampling of prestressing steel · IS 1608 Part 1 — tensile test · IS 456 — concrete

IS 1785 Part 2 is reaffirmed and exists specifically to be distinguished from Part 1: it is as-drawn (not stress-relieved) prestressing wire, with higher relaxation and a different stress-strain response. The one practitioner imperative is condition discipline — 'plain hard-drawn PSC wire' is not one product, and for general prestressed structural design the stress-relieved Part 1 condition is what is normally specified and assumed in the IS 1343 loss calculation. Supplying Part 2 where Part 1 was designed inflates long-term prestress loss beyond the design allowance and quietly under-prestresses the structure. If as-drawn wire is genuinely intended, its higher relaxation must be the value used in the loss calc. Beyond that, the universal prestressing rules apply: test-verify per IS 10790 Part 1, never accept on coil tags, and protect absolutely from nicks and corrosion.