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RE: LRFD Manual Ex 5.1 page 5-12 to 5-16

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Sam -

??

0.38*sqrt(29000/50)=9,152 < 9.92, so the flange is noncompact, just like the
footnote says.

The 0.56*sqrt(E/Fy)=13.49 is a slender element.

In the column tables, when it says "Flange is not compact", I don't think
this affects the axial capacity until you get to 0.56*sqrt(E/Fy) ("Flanges
of I-shaped sections in pure compression, ..., Table B5.1).

If I'm reading the specification correctly, the flanges are non-compact yet
fully effective from (0.38 to 0.56)*sqrt(E/Fy). The issue about being
non-compact is, again, if I'm reading it correctly, is purely a flexural
issue. Otherwise, if you exceed 0.56*sqrt(E/Fy), the flange is slender and
is subject to Eqn A-B5-5, Appendix B5.3a(b).

Sooo...I think the flange in a W12x65 with Fy=50 ksi is fully effective when
considering _pure compression_.

But I could be wrong.

T. William (Bill) Allen, S.E. (CA #2607)	
ALLEN DESIGNS	
Consulting Structural Engineers	
http://www.AllenDesigns.com	
V (949) 248-8588	 .	 F (949) 209-2509	

||-----Original Message-----
||From: Szuchuan Chang [mailto:szuchuan(--nospam--at)gmail.com]
||Sent: Thursday, February 03, 2005 12:30 PM
||To: seaint(--nospam--at)seaint.org
||Subject: Re: LRFD Manual Ex 5.1 page 5-12 to 5-16
||
||On page 4-25, Table 4-2,
||Why is W12x65 Fy=50 ksi listed as flanges is non-compact?
||
||bf/2tf = 9.92
||
||lamda_p = 13.49
||
||Is there a mistake?
||
||Sam
||
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