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RE: Fire Rating

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Is it simply the thickness of the flange?  From what I have seen in the UL
manual the definition of beam size is: "For fire resistance purposes, the
minimum beam size is expressed in terms of a W/D ratio, where W is the
weight of the beam per lineal foot and D is the perimeter of protection
material at the interface between the steel section and the protection
material. Accordingly, beams of the same configuration and having a greater
W/D ratio than the beam size specified in the fire resistive design are
considered larger than the specified minimum beam size and may be used in
that design."

So what I have typically done is knowing the perimeter of protection profile
for the assembly (there are four typical perimeters, A - D in the AISC 9th
edition beginning on page 1-140) taken the minimum beam size in the assembly
and compared its W/D ratio to the beam I've chosen; if the W/D ratio is
greater than W/D min it's OK, if not, I choose and check another beam size.
Is this approach correct, or am I missing something?

Albert J. Meyer, Jr., P.E.
Martin Engineering

-----Original Message-----
From: Scott, William N. [mailto:William.Scott(--nospam--at)veco.com]
Sent: Thursday, February 21, 2002 4:33 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Fire Rating


Thickness of the flange.

You may use the method in the UL book to select alternative beams to W8x28

-----Original Message-----
From: Brian K. Smith [mailto:smithegr(--nospam--at)bellsouth.net]
Sent: Thursday, February 21, 2002 12:01 PM
To: seaint(--nospam--at)seaint.org
Subject: Fire Rating


	I think this has been discussed before; however, I do not remember
the
outcome.  I have a partial garage (one row of parking) under the main floor
of an office.  When we began the project, there was no need to fire rate the
floor between the two.  Now that it is permit time, we have to rate the
floor system separating the two.  My client has faxed over some cut sheets
from the U.L. manual (I do not have copies of the entire manuals).  The
particular system he chose requires a minimum floor beam size of W8x28.  My
beams are deeper, but not as heavy (short span).  What is U.L.'s criteria
for MINIMUM?  Is it depth, weight, flange size?

Brian K. Smith, P.E.


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