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Re: Horizontal reinforcing in IBC foundation walls

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It seems contradictory that ACI 332 requires horizontal steel for residential walls, yet they make no mention of horizontal steel in 318-02 Chapter 22 Structural Plain Concrete for light commercial structures?
 
ACI 332 requires (3) horizontal bars for up to 8' walls and (4) bars for taller walls.  That sounds possibly reasonable.  Maybe (1) top and bottom is enough.
 
In this case, neither seismic or wind is critical.
 
Jim
 

"Jordan Truesdell, PE" <seaint1(--nospam--at)truesdellengineering.com> wrote:
I believe a #4 at the top and bottom are required, though I can't
remember the paragraph. IBC prescriptive foundation walls violate
practically all of the spacing and minimum steel provisions of ACI318,
and current top-of-wall connections between foundation walls and the
diaphragm violate load path physics (up through 2003).

You will find that additional reinforcing may be required based on the
seismic design category, and no mention of such reinforcing is made in
the vicinity of the prescriptive design tables (I know that's the case
in the IRC; not certain in the IBC).

Settlement and shrinkage cracks generally don't become critical within
the 1/5 year warranty required by my state, so builders don't give a
rats @ss about the steel, and temperature steel in foundations that are
constantly held between 55F and 70F isn't really necessary (at least, I
presume that's the logic for omitting it by the IBC). It's either that
or the prescriptive walls tend to be in buildings small enough that only
a few people will die in the event of a failure, so that's okay in the
eyes of the ICC (and their builder-lobby members). *shrug*

Jordan



Jim Wilson wrote:
> The IBC provides prescriptive design tables that allow some concrete
> foundations to have little or no vertical reinforcing. The code
> appears to be absent on horizontal reinforcing, yet that is often the
> first failure mode due to settlement and/or wall shrinkage. Is there
> a minimum horizontal reinforcing requirement requried by the IBC that
> I am missing? This is not a crack critical wall. And this NOT an
> engineered wall - I am only looking for code interpretation and good
> practice info.
>
> If there needs to be horizontal reinforcing, vertical steel would be
> required to support the horizontal bars. What is an appropriate
> spacing for this purpose? 8ft?
>
> Jim Wilson, PE
> Stroudsburg, PA
>
>

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