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Re: Concrete Fire protection

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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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