Torsion in wide flange
Torsion in wide flange
(OP)
Is the Ix or Iy axis in the moment of inertia or/and the Wx or Wy axis in the section modulus of the wide flange has more to do with torsion resistance? Which, Ix, Iy, Wx, Wy is more related to torsion resistance?
See the animation of the torsion in:
https://en.wikipedia.org/wiki/I-beam
Most wide flange have large Ix, Wx and small Iy, Wy values.. should you get one with higher value of Iy, Wy to get more torsion resistance? Higher Iy, Wy also also happened to be a preference to use as column because of higher biaxial resistance. Is this also true for torsion?
I think this is related to warping constant. In short. Warping constant is more to do with Ix, Iy, Wx, or Wy?
See the animation of the torsion in:
https://en.wikipedia.org/wiki/I-beam
Most wide flange have large Ix, Wx and small Iy, Wy values.. should you get one with higher value of Iy, Wy to get more torsion resistance? Higher Iy, Wy also also happened to be a preference to use as column because of higher biaxial resistance. Is this also true for torsion?
I think this is related to warping constant. In short. Warping constant is more to do with Ix, Iy, Wx, or Wy?






RE: Torsion in wide flange
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Torsion in wide flange
For secondary wide flange that frames into the primary wide flange at one side only.. it sure can introduce torsion.. is it not.. so I guess the preference for larger values of Iy/Wy looked for in steel column design is also good for beam torsion resistance. Do you handle torsion by looking for higher values of Iy/Wy which can become expensive or put plates on the flange sides?
RE: Torsion in wide flange
BA
RE: Torsion in wide flange
I said framing at one side only. This is the same as framing in eccentricity.. because the primary wide flange would twist to the right slightly if there is only one secondary beam framing at the right side with no beam on the left. This is called eccentrically.. is it not.. what else do you mean by framing in eccentrically then?
RE: Torsion in wide flange
What does your connection look like? Show us a detail.
BA
RE: Torsion in wide flange
Actually the "secondary beams" are just C-purlins welded 23.5" on top of the primary wide flange which functions as rafter of a gable joined at the middle with center ridge.. and the roofing used will be light sheeting.. but when the wind bears down on the roof sheet such as during hurricane.. the purlin can vibrate and won't this introduce torsion to the primary wide flange?
RE: Torsion in wide flange
BA
RE: Torsion in wide flange
You need to distinguish between compatibility torsion and equilibrium or stability torsion. It is common practice to ignore compatibility torsion, but you must design for equilibrium torsion.