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RE: Drop Panels

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Scott,

Yes the term Drop Cap is not officially used in ACI but there does need to be a differentiation. If there is not one then over time the difference will be lost and designers will treat them incorrectly, as has happened with Drop Caps/DRop Panels in my experience. New designers coming into the profession do not know the old usage and make mistakes in their use.

At 03:01 PM 10/07/02 -0400, you wrote:
Gil,

I stand corrected.  Thanks for pointing out that a drop panel can in fact
cause an adjustment in the slab reinforcement, as you alluded to (the ACI
318 section is 13.3.7...at least in the 2002 edition).

I would still argue that what I was describing is still a drop panel in
the eyes of ACI.  A search of the ACI MCP of the term "drop cap" does not
turn up any thing at all.

It would appear from the ACI 318 provisions that both conditions are
considered a drop panel (i.e. whether it is wider than l/6 or not).  The
difference is that _IF_ you wish to use a drop panel to reduce the amount
of negative moment reinforcement, then the drop panel MUST be at least l/6
in width as you pointed out.  Beyond that, however, a drop panel (or drop
cap if you wish) does not effect the "normal" slab reinforcement.

As a side note, I have certainly heard the term drop cap used even though
I could not find it in the ACI MCP or my concrete text book (by
MacGregor).  And I have never gotten/remembered the differences between a
drop cap and a drop panel.

HTH,

Scott
Ypsilanti, MI


On Tue, 9 Jul 2002, Gil Brock wrote:

> At 12:44 AM 9/07/02 -0400, you wrote:
> Scott
>
> >Part of my point (which was not well articulated) is that many times the
> >additional punching shear stresses due to the lateral drift/moment
> >transfer have still be traditionally handled by just providing additional
> >concrete depth either just near the column (as in a drop panel) or through
> >out the slab.  As a result, traditionally the inclusion of drop panels
> >_does not_ change the reinforcement in the slab from what it would be
> >_without_ the drop panels.  Typically, the drop panels have only been
> >added to increase the Vc component that resists the punching shear.
>
> I think we need to clarify the definition of Drop Panel with regard to your
> last sentence in this paragraph.
>
> A true Drop Panel extends minimum Span/6 in each direction from the column
> and is used for flexural reinforcement calculations as well as punching
> shear calculations. It does reduce the amount of top reinforcement required
> at a column.
>
> Anything smaller than this cannot be used for flexure calculations and
> should be called a Drop Cap. These are added to increase Vc only. In USA
> practice these are normally about 4' square centered on the column.
>
>
>
> Regards  Gil Brock
> Prestressed Concrete Design Consultants Pty. Ltd. (ABN 99003351504)
> 5 Cameron Street Beenleigh Qld 4207 Australia
> Ph +61 7 3807 8022              Fax +61 7 3807 8422
> email:          gil(--nospam--at)raptsoftware.com
> email:          sales(--nospam--at)raptsoftware.com
> email:          support(--nospam--at)raptsoftware.com
> webpage:        http://www.raptsoftware.com
>
>
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Regards  Gil Brock
Prestressed Concrete Design Consultants Pty. Ltd. (ABN 99003351504)
5 Cameron Street Beenleigh Qld 4207 Australia
Ph +61 7 3807 8022              Fax +61 7 3807 8422
email:          gil(--nospam--at)raptsoftware.com
email:          sales(--nospam--at)raptsoftware.com
email:          support(--nospam--at)raptsoftware.com
webpage:        http://www.raptsoftware.com


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