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# RE: Single angle bending member

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: Single angle bending member
• From: "Gunnar H. Isleifsson" <ghi(--nospam--at)pc.dk>
• Date: Wed, 22 Nov 2006 01:27:37 +0100

Hi Joe,

I haven't seen the AISC Manual, but the equations below are valid, regardless of the shape in question.

If memory serves me correctly, the general formulation is, that the sum of moments of inertia, about the major and minor principal axis, equals the sum of moments of inertia about any cartesian coordinate system, with the same origo, rotated with respect to the principal coordinate system.

There is an article by Y. Ding and M.K.S. Madugula in the Engineering Journal (1st Quarter, 2004) that lists Iz and Iw, for angle sections listed in the AISC LRFD Manual (2001).

Gunnar

From: jrgrill(--nospam--at)cableone.net [mailto:jrgrill(--nospam--at)cableone.net]
Sent: 21 November 2006 23:59
To: seaint(--nospam--at)seaint.org
Subject: RE: Single angle bending member

Thanks Gunnar,

I was actually being a little lazy hoping someone had a list of Iw and Iz.  The formulas on page 17-42 of the manual would be for an angle constructed of plates (no fillets or radius at the toes), so I was hoping there was a tabel somewhere that could be had, so itterative calculations for a beam would be a bit simplified.

Joe

On Tue Nov 21 17:41 , 'Gunnar H. Isleifsson' sent:

You can find Iz and rz from the following equations:

Ix + Iy = Iw + Iz

rz = sqrt(Iz/A)

where
Ix and Iy are moments of inertia about major and minor geometrical axis
Iw and Iz are moments of inertia about major and minor principal axis

HTH
Gunnar Hafsteinn Isleifsson
Denmark

From: jrgrill(--nospam--at)cableone.net [mailto:jrgrill(--nospam--at)cableone.net]
Sent: 21 November 2006 23:21
To: seaint(--nospam--at)seaint.org
Subject: Single angle bending member

I am looking at the design of an unequal leg angle in bending using the new 13th edition of the AISC manual.  In section F.10 I need values for Iz and rz for the unequal leg angle to find Me.  Are these values listed somewhere I am not familier with.  I think I can calculate it from the diagram on page 17-42 but I would rather not make any mistakes.  If I have to is that the correct formula (O.k. maybe a dumb question for someone that has supposed to be educated).  If someone has a list of the values for angles I would love to get a copy, or can anyone tell me where to find the values.

Thanks,

Joe Grill, PE

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