Refer to Table A-F1.1 (pgs. 6-116 and 6-117; second revision of the 2nd
edition of LRFD). It will list the strength limit states and the
corresponding slenderness parameters and what equations to employ when
trying to find moment capacity (for symmetric box sections).
Robert C. Rogers, PE
From: Jones, Mark A (Battle Creek) [mailto:Mark.A.Jones(--nospam--at)jacobs.com]
Sent: Tuesday, January 16, 2001 10:59 AM
To: SEAINT mailing list (E-mail)
Subject: Strength of Non-Compact HSS
What is the formula for reducing the strength of non-compact HSS?
LRFD, pg4-8 gives the formula
phi.b Mn = phi.b Mp - phi.b(Mp-Mr)[(Lb-Lp)/(Lr-Lp)].
But the section says that this is for I or C rolled shapes only.
LRFD, App. F, pg 6-11 gives (substituting l for lambda)
Mn = Cb[Mp - (Mp-Mr)[(l-lp)/(lr-lp)]
Can I use the second formula for any shape?