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RE: ASD Table B5.1

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The variable h is the clear depth of the web. Strictly speaking, this is 
the distance from toe of fillet at one flange to toe of fillet at the other 
flange. But h can be conservatively taken as the depth between flanges if 
you don't want to mess with the fillet radius. The variable t is the web 

The web does affect the buckling strength of the flange for an I-shaped 
member. If the flange is to buckle, it does so in a rotational mode (when 
one flange tip goes up, the other has to go down). The web is along for the 
ride and will provide some resistance, depending upon its relative 


-----Original Message-----
From:	Andrew Abbo [SMTP:AndrewA(--nospam--at)]
Sent:	Friday, July 23, 1999 2:37 AM
To:	seaint(--nospam--at)
Subject:	ASD Table B5.1

In table B5.1 of ASD, foot note e defines an expression compression
element restraint coefficient, kc. This expression includes the ratio
h/t.  What is the definition of h and t used in this equation? While I
think that h is well defined, the value of t is open to interpretation
as either tw (web thickness) or tf (flange thickness).

 I have been given different interpretations of both h and t by
different people, all of which have some merit. They are

(1) h is the clear distance between the flanges (height of the web) and
t is the thickness of the flange (t=tf).
(2) h is the clear distance between the flanges (height of the web) and
t is the thickness of the web (t=tw).
(3) h is the width of the compression element which, in the context
Table 5.1, is the width of the flange and t=tf.

I think that (2) is the correct interpretation and this is backed up by
the Example 12 and Page 2-220 of the green book (9th Edition). However,
it does seem unusal that the local buckling capacity of a flange is
related to the stiffness of the web. Can someone please expand this.



Andrew Abbo - AndrewA(--nospam--at)
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