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# Re: Concrete tension capacity

• To: <seaint(--nospam--at)seaint.org>
• Subject: Re: Concrete tension capacity
• From: Scott Maxwell <smaxwell(--nospam--at)engin.umich.edu>
• Date: Sun, 8 Sep 2002 01:17:17 -0400 (EDT)

```Take a look at chapter 22 of the ACI 318...it deals with the design of
structural plain concrete (i.e. unreinforced).

Section 22.5 addresses strength design of structural plain concrete.  Eq
22-2 gives the nominal moment capacity of a plain concrete section if
tension controls (the 2002 edition is this specific where the 1999 does
not specifically state that it is for tension controls, but that is still
the end result):

Eq 22-2   Mn=5*sqrt(f'c)S

where S is the corresponding elatic section modulus.

Thus, using good old solid mechanics (stress=My/I or M/S), the limiting
tensile stress is 5*sqrt(f'c).

Obviously, when actually doing the design, there is an added factor of
safety when the effect of phi is included.  The limiting design tensile
stress will be phi*5*sqrt(f'c) or .9*5*sqrt(f'c) or 4.5*sqrt(f'c).

HTH,

Scott
Ypsilanti, MI

On Sat, 7 Sep 2002, Ib sa wrote:

> Does anyone know if there is a  formula in  the ACI code that gives the capacity of concrete in tension without any reinforcment.  I have used 10% of the concrete strength.
>
> Thank youGet more from the Web.  FREE MSN Explorer download : http://explorer.msn.com
>

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