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RE: Horizontal reinforcing in IBC foundation walls

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The minimum reinforcing assumes that the foundation behaves as plain
concrete.

Bill 

-----Original Message-----
From: Jordan Truesdell, PE [mailto:seaint1(--nospam--at)truesdellengineering.com] 
Sent: Wednesday, April 11, 2007 8:30 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Horizontal reinforcing in IBC foundation walls

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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