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[arun.kashikar]

If I recollect correctly IS:13920 puts upper limit on yield strength of reinforcement as 415MPa.

Regards,


Arun Kashikar


-----Original Message-----
From: inchak@tatasteel.com [mailto:inchak@tatasteel.com]
Sent: Tuesday, July 12, 2005 9:32 PM
To: KASHIKAR Arun
Subject: [Econf] Message No 32 - Guaranteed min & Max strength of rebar


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SEFI e-Conference on Steel Reinforcement from June 27 to July 17, 2005
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Dear Mr. Vipul Ahuja,
Excellent point
I reproduce your concern
QUOTE
Back in the 80's in the US,a need felt among structural engineers for
weldable "Tor" steel to be available to them that not only had a guaranteed
minimum strength but also a maximum strength. The reason was that in order
for the strong column weak beam theory to be implemented properly the beam
steel could not be stronger than the column steel in terms of material
strength. Also weldability avoided the usual site problems. The answer from
the industry to this was ATMS A706 bars.
Do we have an IS equivalent to this and if not is there any hope in the
near future.

UNQUOTE

You are quite correct.
BIS does not have any upper limit on strength. Only lower limt is there.
However we have realized the importance of this upper limit and offered to
provide BOTH upper and lower limits to the Yield strength in line with not
only the ASTM A 706 but also the Australia / New Zealand code   as follows:
1) YIELD STRENGTH (MPa) MIN. which decides the design load
IS 1786(Fe 415) - 415
Euronorm - 450
ASTM A706 (GR 60) - 420
Australia / New Zealand (500 N) - 500
Australia / New Zealand (500 NE) - 500
TATA STEEL Super Ductile Rebars - 415

2) YIELD STRENGTH (MPa) MAX. Some, but not all specifications put a cap on
the maximum permissible yield strength. The idea is that the bar should not
unduly resist plastic deformation (yielding) thus allowing excessive stress
to build up in the concrete. The various specifications stand thus:IS
1786(Fe 415) - NA
Euronorm - NA
ASTM A706 (GR 60) - 540
Australia / New Zealand (500 N) - 650
Australia / New Zealand (500 NE) - 600
TATA STEEL Super Ductile Rebars - 550

Please let me know if you find this to be a step in the right direction.
However to get it incorporated in the Indian Specification(s) you need to
initiate the process with the Bureau of Indian Standards.


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