Torsion in Steel Beam
Torsion in Steel Beam
(OP)
I'm looking for ideas for negating torsion in a steel I-Beam. What we are dealing with is a beam supporting floor joists on one side with the other side being an exterior wall. Have any of you dealt with this type of situation before? The floor joists are a few inches shorter than the steel beam will be, so they aren't flush on the bottom flange.






RE: Torsion in Steel Beam
BA
RE: Torsion in Steel Beam
RE: Torsion in Steel Beam
plate approx 3/4 of span
stitch welded
1/4" thick plate up to 24" deep beam
You may need access holes to install bolts for your joists (I assumed the bolt on?) - adds a bit more complexity to the detailing
Note: I assume it will be shop welded(?)... the plate welds will pull a sweep into the beam. We pre-sweep the beam in opp direction to allow it to pull back to reasonably straight.
RE: Torsion in Steel Beam
RE: Torsion in Steel Beam
RE: Torsion in Steel Beam
1) require the joist reaction to be centered on the beam, by extending the joist seat across the flange of the beam. Depending on the flange width of the beam, this may cause the seat to be deeper and push the top of steel lower. $
2) brace the bottom flange with a strut from the joist. If the bottom of beam is less than the bottom of joist, extend the brace from the nearest top chord panel point. $
I think most people ignore the torsion and call it good. I'm not sure exactly what happens when it's ignored, but I guess the the beam rotates and induces a moment back into the joist? How do you all handle this?
RE: Torsion in Steel Beam
I've seen torsional issues due to shear plate connections all on the same side of a beam. The beam (a W12 x 14; a horrible section for any torsion) was perfectly fine for the vertical loads but it twisted noticeably when loaded. We didn't recognize the torsional mode. Luckily it was an easy fix and not a change order.