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RE: IBC Special inspection for Slab-on-Grade supporting HVAC unit.

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Actually, when I first read the question, I thought that Elias was asking about the building code so he could discuss it with a building code official or plan reviewer.  They always use common sense don't they.
And yes, Ms. Kelly is quite correct.  It seem that wants ACI 318 to cover everything concrete.
My only hope is that Rkazanjy doesn't do much mentoring with that attitude.  I've always told the staff I'm mentoring that the only "stupid" questions is the one unasked.  Besides, normally it's because the wrong question on the right topic is being asked.
My thoughts.
-----Original Message-----
From: GSKWY(--nospam--at) [mailto:GSKWY(--nospam--at)]
Sent: Monday, May 30, 2005 7:08 AM
To: seaint(--nospam--at)
Subject: Re: IBC Special inspection for Slab-on-Grade supporting HVAC unit.

In a message dated 5/27/2005 8:32:50 PM Eastern Daylight Time, rkazanjy(--nospam--at) writes:

Are there no senior engineers with common sense to share at your firm?
Actually,  I thought the original question was good.  Much better than some of the answers,  particularly this one, which was  one of the stupidest I have read in a while:
"My main point was that Elias had totally lost sight (if he ever had sight) of common sense reality & was way too focused on finding (in the wrong spec) something to hang his hat on; the typical refuge of the code monkeys who seem to predominate in the CE/SE world."

The question "why is a slab-on-ground not covered in ACI 318" comes up repeatedly because no one seems to understand it.  That would certainly be supported by the answers given on this list.
Slabs-on-ground are not covered in ACI 318 because they are not considered structural concrete.
The question of structural versus nonstructural has nothing to do with a "use category that is considered life essential."
The question of structural versus nonstructural  has nothing to do with whether the slab is stiffened.
The question of structural versus nonstructural has  nothing to do with whether the slab is designed to resist flexure and shear.  Slabs-on-ground designed using the PCA, WRI, and COE tables and nomographs are designed to resist loads in flexure.    Depending on the loading, it may also be necessary to check for shear. 
And no where in any code have I found a reference to "air-supported slabs."
Slabs-on-ground are considered nonstructural unless they transmit loads or forces from other portions of the structure to the soil.  A slab-on-ground would only be considered structural if it supported some portion of the structure, such as a mezzanine or the roof.
Slabs-on-ground are specifically excluded from ACI 318 by section 1.1.6:
"1.1.6 — This code does not govern design and construction of soil-supported slabs, unless the slab transmits vertical loads or lateral forces from other portions of the structure to the soil."
Slabs-on-ground are specifically excluded from ACI 318 because the design methodology differs from that of a structural element.  (Not because members of ACI Committee 360 decided that was the way it should be.)
Slabs-on-ground were first specifically excluded in 318-95 with the only exception being slabs that transmit vertical loads to the soil.  This was amended in 318-99 to include slabs that transmit lateral forces.
While much of  ACI 318 can be applied to slabs-on-ground as good practice,  the requirements have to be specifically stated in the project specifications.
Gail Kelley