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Re: Concrete Fire protection

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That is basically what I am figuring, but it would be nice if they talked
a little about that in the document (which they might...I did not sit down
and read the thing too much...just skimmed it to see if it might help you
some).  I can understand that the slab above might be more "at
risk"...after all, heat does rise.  I have to believe those that something
that is burning right on top of a slab should still have SOME effect on
it...of course, many burning items may not sit directly on a slab.

Scott
Adrian, MI


On Thu, 12 Jan 2006, Paul Feather wrote:

> Thanks for the reference Scott.
>
> The fact is the fire, even on an intermediate floor, does not heat the top
> of the slab the same as the bottom of the opposing floor.  The items burn,
> ie furniture walls etc, but like a camp fire the lower slab is subjected to
> radiant heat until the objects literally rest on the slab as coal, whereas
> the slab above is cooked.  Just like a camp fire you can stand next to the
> thing, just don't try and suspend your self over it.  Even burning debris
> falling on the floor does not have the same intensity, the side on the floor
> is deprived of oxygen.
>
>
> Paul Feather PE, SE
> www.SE-Solutions.net
> pfeather(--nospam--at)SE-Solutions.net
> ----- Original Message -----
> From: "Scott Maxwell" <smaxwell(--nospam--at)engin.umich.edu>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Thursday, January 12, 2006 10:56 AM
> Subject: Re: Concrete Fire protection
>
>
> > Paul,
> >
> > I am assuming that you have looked at the couple of ACI 216
> > documents...but if not they might help some.  I will note that in my brief
> > review (in the past couple minutes) it appears that ACI 216R-89 primarily
> > considers a situation where the fire is located below the slab, which
> > would make the top bars less "exposed" to heat issues.  The documents does
> > not seem to address what that same fire would do to slab that is below it
> > (i.e. the fire closest to the top bars).  For example, take a intermediate
> > floor with a fire on it...you will now have fire exposure on the slab that
> > supports that floor (thus with heat closest to top bars) and the slab that
> > support the floor above (thus with heat closest to the bottom bars of that
> > slab).
> >
> > Regards,
> >
> > Scott
> > Adrian, MI
> >
> >
> > On Thu, 12 Jan 2006, Paul Feather wrote:
> >
> >> Thanks Ben,
> >>
> >> Question, does the UBC code specifically address top and bottom steel?
> >> In the IBC the code specifically addresses bottom steel.  All the fire
> >> research on concrete slabs I have been able to read is consistent with
> >> this: the negative moment reinforcing stays much cooler since even with a
> >> fire on the level above the heat does not spread evenly up and down.  The
> >> flammable elements burn with predominate heat flow to the slab above, and
> >> the critical aspect for fire endurance is the positive moment reinforcing
> >> cover.
> >>
> >>
> >> Paul Feather PE, SE
> >> www.SE-Solutions.net
> >> pfeather(--nospam--at)SE-Solutions.net
> >>   ----- Original Message -----
> >>   From: Ben Yousefi
> >>   To: seaint(--nospam--at)seaint.org
> >>   Sent: Thursday, January 12, 2006 8:26 AM
> >>   Subject: RE: Concrete Fire protection
> >>
> >>
> >>   The separation applies to both sides of the element. The only condition
> >> that code waives the requirement on one side is there is unoccupied space
> >> such as roofs and crawl spaces. So, you would need to have the cover for
> >> both top and bottom reinforcement.
> >>
> >>
> >>
> >>   Ben Yousefi, SE
> >>
> >>   Santa Monica, CA
> >>
> >>
> >>
> >>
> >> ------------------------------------------------------------------------------
> >>
> >>   From: Paul Feather [mailto:pfeather(--nospam--at)SE-Solutions.net]
> >>   Sent: Wednesday, January 11, 2006 5:05 PM
> >>   To: SEAOC List
> >>   Subject: Concrete Fire protection
> >>
> >>
> >>
> >>   Hello all,
> >>
> >>
> >>
> >>   Please assist me with my interpretation of fire rating requirements.
> >> For a concrete slab to provide a four hour separation between a garage
> >> and the occupied spaces above, is the minimum coverage requirement for
> >> the bottom of the slab, or both top and bottom?
> >>
> >>
> >>
> >>   My interpretation was that since the separation is required for vehicle
> >> fire upward, the top reinforcement cover would be unaffected.
> >>
> >>
> >>
> >>   Does anyone have a good reference for this topic?
> >>
> >>
> >>
> >>   Paul Feather PE, SE
> >>   www.SE-Solutions.net
> >>   pfeather(--nospam--at)SE-Solutions.net
> >>
> >
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