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Re: Torsion in wide flange shapes

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My preference is for the HSS (Tube Steel) properties.

Pax e Gratia
Robert P. "Bob" Ross, P.E.
Civil-Structural Engineer
Washington Group International,Inc.
Industrial Processes
17320 Red Hill, Suite 300
Irvine, Ca. 92614
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----- Original Message -----
From: Scott Maxwell <smaxwell(--nospam--at)engin.umich.edu>
Date: Tuesday, January 8, 2002 12:27 pm
Subject: Re: Torsion in wide flange shapes

> Mark:
>
> This can get a little complicated.  If you are dealing with a
> closed shape
> (i.e. a tube) then torion can be a relatively simple thing to deal
> with.In that case you will only have to deal with torion stress
> that are in the
> form of shear stresses.
>
> Open shapes, however, are a whole different ball game.  Torsion
> stressesin open shapes (i.e. a wide flange section) will produce
> both shear
> stresses and normal (axial/bending) stresses.  When dealing with open
> shapes, the torion can be "broken down" into St. Venant torsion (pure
> shear stresses) and Warping torsion (both shear stresses and
> axial/bendingstresses).  The St. Venant torion is basically
> similar to the torsion in a
> closed shape.  The warping torions is something that only occurs
> in open
> shapes.  It is actually somewhat in intuitive if you really think
> aboutit.  Imagine in your mind an I-beam twisting...you should be
> able to see
> the flanges warping as it is twisted...and it should be somewhat
> apparentthat there will be some normal stresses introduced due to
> the deformation
> "shape" of the I-beam.
>
> The end result is that the whole torsion issue is rather
> complicated for
> open shapes (I only got my introduction to it in a PhD level
> course...which was VERY helpful).  Thus, I would suggest that you
> wait for
> the AISC Design Guide to arrive if you can.  It will do a good job of
> helping you deal with the complicated issue.  I believe that
> Design Guide
> is based off of a publication that Bethlehem Steel (?) produced on
> designing for torsion, but I think AISC has added much more
> explanationsthat the Bethlehem Steel publication (which just
> confused me...especially
> since I had not taken my course that contained torsion yet).
>
> HTH,
>
> Scott
> Ypsilanti, MI
>
>
> On Tue, 8 Jan 2002, Harper, Mark wrote:
>
> > I have a condition where there is some torsional force
> introduced in the
> > column due to the geometry of the precast connection.  My
> question is
> > this, What unity check do I have to make if any?  Generally I
> would make
> > a combined bending  and torsional stress  check but I am not
> sure about
> > axial load and torsion.  Would it be fa/Fa + Tv/Fv <=1  Or maybe
> fa/Fa +
> > ( Torsional bending stress/Fb)<=1 ???
> > I have ordered the AISC Steel design guide 9 on torsion, but would
> > appreciate any input.
> > Thanks,
> > Mark
> >
> > Mark Harper PE, SE
> > HDR INC.
> > 201 South Lake Ave. #705
> > Pasadena, CA 91101
> > mharper(--nospam--at)hdrinc.com
> > Phone: (626) 584-1706
> > Fax: (626) 584-1750
> >
> >
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