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Re: Steel Reinforcement Elongation Limit

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Concrete is assumed to take no tension, therefore the cracking strain is 
zero.  Code permitted moduli of rupture vary between 6sqrtf'c to 12sqrtf'c, 
but this is valid only up to when concrete cracks.  Once cracking occurs the 
moduli of rupture is zero.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Jim Korff wrote:

<<Roger,

Thanks for a good answer....

However...it leads me to the question......what value do you utilize for the
cracking strain of concrete.... .003 ... .004...  .005.....or is that also
irrelevant in our code dominated world..... ??

jim


From: "Roger Turk" <73527.1356(--nospam--at)compuserve.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, July 25, 2000 6:41 PM
Subject: Steel Reinforcement Elongation Limit


> ASTM requires 11 to 12 percent (min.) for Grade 40 steel, and 7 to 9
percent
> for Grade 60 steel.
>
> Since this is much beyond the cracking strain of concrete, the concrete
will
> crack and go along for the ride.  (Take a piece of paper and cut one edge
in
> parallel strips and glue a rubber band across the strips.  Pull the rubber
> band and see if the glue comes loose.)
>
> At these strains, deflected shape becomes a part in determining the
capacity
> of the structure with the structure behaving like a cable supported
structure
> more than a flexural member.
>
> We (at least *I* do) want our structures to look like a sway-backed mule
> before it collapses.  I do not want strains limited so that collapse comes
> suddenly and without warning.!
>
> A. Roger Turk, P.E.(Structural)
> Tucson, Arizona
>
> Jim Korff wrote:
>
> >>The steel reinforcement "yield point" is at an elongation of .002
(0.2%)
>
> Does ACI Code give a maximum permitted elongation for internal
reinforcement
> ??
>
> (For DIN it is 0.5% and for the Euro Standard it is 1.0% )
>
> Are there any papers or research on this subject -maximum elongation to
> avoid steel/concrete bond failure ??<<>>

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