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RE: [SEAOC] Yield strength of structural steel shapes

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You Said: 

> From:	SMTP%"seaoc(--nospam--at)" 23-MAR-1996 08:45:14.08
> To:	U5938
> CC:	
> Subj:	[SEAOC] Yield strength of structural steel shapes
> From: HHuang2(--nospam--at)
> Date: Sat, 23 Mar 1996 10:18:02 -0500
> Message-ID: <960323101801_253874443(--nospam--at)>
> To: seaoc(--nospam--at)
> Subject: [SEAOC] Yield strength of structural steel shapes
> Sender: owner-seaoc(--nospam--at)
> Precedence: bulk
> Reply-To: seaoc(--nospam--at)
> It appears that there is a difference of yield strength for structural steel
> (Fy) between Mill Cert and results of lab coupon tests.  Anybody know if
> there are test data showing the relationship between the two?  Which number
> do you suggest for evaluation the capacity of an existing structure?

The Mill Cert certifies that the steel meets the minimum yield strength
requirements of the applicable ASTM specification, such as A36 steel meeting a
minimum yield strength of 36 ksi.  Just as with concrete strength, though, the
steel industry aims for a strength higher than the minimum requirement, on the
assumption that normal variations in manufacturing processes will produce a
"scatter" in yield strength distribution.  Their goal is to ensure that all, or
almost all of the steel will show a strength meeting the minimum yield or

Laboratory testing results will show the "scatter" that's the basis of the
specification.  Design for the yield strength on the Mill Cert, unless the test
results show a strength below the Mill Cert.  In that case, you'd have to come
up with some scheme of your own for an appropriate yield strength to use in
design, such as assuming the lowest lab result represents a safe number, while
hoping your testing hasn't missed any steel that's weaker.