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RE: Concrete Fdtn at High Temps

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You basically have a stack.  All of your temperature transfer, details, and basic loading questions can be answered in ASME STS-1-1992, Steel Stacks.  The effect on concrete has many variables and depends on the concrete mix.  Reference "Handbook of Concrete Engineering", by Fintel.  1000 degrees is not a big problem, but some adjustments are required.

Harold Sprague, PE
Krawinkler, Luth & Assoc.


-----Original Message-----
From:	MSSROLLO(--nospam--at)aol.com [SMTP:MSSROLLO(--nospam--at)aol.com]
Sent:	Monday, September 07, 1998 8:47 AM
To:	seaint(--nospam--at)seaint.org
Subject:	Concrete Fdtn at High Temps

I am working on a project where I have to support a steel pipe used as a vent.
The pipe is routed up the exterior wall and is estimated to be about  1000
degrees F.

I want to support the pipe from below with a concrete pedestal/footing but am
not well-versed in concrete at elevated temperatures of this magnitude.  The
pipe will be secured to the building for lateral loading, therefore, the
footing is only supporting the gravity weight of the pipe (about 14 kips).  

Since the pipe is connected to the concrete pedestal, I am sure the concrete
will elevate in temperature.  Anyone got any thoughts on how to best design
for the potential elevation in temperature or any means to isolate the base of
the pipe so that only minimal temperature rise takes place?

In addition to this, the pipe is free to elongate up the wall.  It is only
supported vertically at the base.  If I do not restrain the pipe from moving
upwards, I do not see needing any reinforcement around the circumference of
the pipe.  The pipe will be free to expand radially and longitudinally.  Is
there any obvious flaw in that thinking?  I have already adjusted the modulus
of elasticity, Fy and the thermal expansion coefficient for the elevated
temperature.  The pipe is not made from a heat-treated material.

Thanks for any help
Ron Martin, PE

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