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

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Elias,

Stan basically answered your question...but to say it a again, SOGs are
generally NOT structural.  Technically, it is the SOIL that is doing the
"work" not the slab.  For a SOG, the slab will generally be designed to
minimize cracking if the soil does consolidate in local spots, but the
whole idea of a slab on grade is that it is the soil that is supporting
the loads.  This is precisely why ACI 318 does not apply to SOGs...they
are non-structural and ACI 318 is for STRUCTURAL concrete.

I will kind of disagree with Stan some...if the SOG is designed for wheel
loads, I believe it is still considered to be non-structural.  For such
conditions, it is still generally the soil that takes the load with the
slab being "stiffed" to help spread the load a little more.  If the SOG is
designed to span some distance, then it might be considered structural.

Thus, the "non-structural slabs supported directly on ground" exception
that you cite applies to your case...at least based upon the information
that you gave, that would appear to the be the case.

Regards,

Scott
Adrian, MI


On Fri, 27 May 2005, Elias Hahn wrote:

> I tend to agree, but I can't find anything to cite.  There are only four
> exceptions given in the IBC - Isolated spread footings (under 3 stories),
> Continuos footings (some requirements), "non-structural slabs supported
> directly on the ground." and some foundation walls.
>
>
>
> So, my follow-up question - what differentiates a structural slab and a
> non-structural slab?
>
>
>
>   _____
>
> From: Arvel L. Williams, P.E. [mailto:awilliams(--nospam--at)gwsquared.com]
> Sent: Friday, May 27, 2005 12:52 PM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: IBC Special inspection for Slab-on-Grade supporting HVAC unit.
>
>
>
> Elias,
>
>
>
> Unless the existing building is in a use category that is considered life
> essential.  Such as a hospital, water plant, etc.
>
> Even then, its a long shot on this type of foundation.  Special Inspection
> is usually required only on deep foundations, deep fill, some type of
> structural steel, pre and post tension concrete and a few other items that
> are "special applications" and all building 3 stories and taller.
>
>
>
> So, for your little mat, I would say no.
>
>
>
> Arvel
>
> -----Original Message-----
> From: Elias Hahn [mailto:ehahn(--nospam--at)eepdx.com]
> Sent: Friday, May 27, 2005 1:22 PM
> To: seaint(--nospam--at)seaint.org
> Subject: IBC Special inspection for Slab-on-Grade supporting HVAC unit.
>
> I recently designed a SOG (~10'x15', 6" thick, thickened edge) for a HVAC
> unit (~1000lbs) for an existing building.  Our standard general notes call
> for special inspection for steel and concrete placement.  Is this
> applicable?  There is very little good information on SOGs in either the IBC
> or ACI 318.
>
>
>
> Thanks in Advance,
>
> Elias Hahn, EIT
>
> Evergreen Engineering, LLC
>
>

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