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RE: Concrete Fire protection

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Paul

 

I have seen intense fires that also wrap around the building edges and burn everything on top. So, I wouldn’t take a chance on the top bars. Santana Row Fire in San Jose opened my eyes to how deficient actually the concrete cover requirements in the code are for rebars. The three hour slabs didn’t even last an hour before showing serious signs of structural distress.

 

Ben Yousefi, SE

Santa Monica, CA

 


From: Paul Feather [mailto:pfeather(--nospam--at)SE-Solutions.net]
Sent: Thursday, January 12, 2006 9:18 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Concrete Fire protection

 

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.

 

 

----- Original Message -----

From: Ben Yousefi

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?