Elimination of Torsion on Steel Spandrel Beam due to Curtain Wall Load
Elimination of Torsion on Steel Spandrel Beam due to Curtain Wall Load
(OP)
Hello,
I have the condition shown on the attached image. Every 8 ft, a stub cantilever channel and a W16x26 frame into the spandrel beam shown in the sketch. Obviously the curtain wall will cause torsion which we want to eliminate. I'm thinking of adding the two kickers shown to accomplish this, although I'm not sure how to resolve the forces if I were to do this. I'm using example 6.4 on AISC Design Guide 22 as a reference, but it seems the condition I have here is a bit different due to the channel and the extra kicker.
Another option I was thinking about is using the W16x26 as "roll beams" as they do in example 6.3 of design guide 22, but I'm not sure if there are any restrictions due to the difference in depth between the spandrel beam and the W16x26 beam.
I would also like to know if there is a good way to model this on any software for purposes of checking hand calcs. I'm not sure if these are the best solutions for the condition shown, but if you think there are better options, I would like to hear it. Thank you.
I have the condition shown on the attached image. Every 8 ft, a stub cantilever channel and a W16x26 frame into the spandrel beam shown in the sketch. Obviously the curtain wall will cause torsion which we want to eliminate. I'm thinking of adding the two kickers shown to accomplish this, although I'm not sure how to resolve the forces if I were to do this. I'm using example 6.4 on AISC Design Guide 22 as a reference, but it seems the condition I have here is a bit different due to the channel and the extra kicker.
Another option I was thinking about is using the W16x26 as "roll beams" as they do in example 6.3 of design guide 22, but I'm not sure if there are any restrictions due to the difference in depth between the spandrel beam and the W16x26 beam.
I would also like to know if there is a good way to model this on any software for purposes of checking hand calcs. I'm not sure if these are the best solutions for the condition shown, but if you think there are better options, I would like to hear it. Thank you.






RE: Elimination of Torsion on Steel Spandrel Beam due to Curtain Wall Load
Based on your proportions, I'd eliminate the kicker on the right side and replace it with a full depth stiffener and bolted moment connection to the roll beam. I did something similar a while back working with a design assist steel fabricator. As long as you keep the moment to less than about 15 kNxm it works nicely.
This doesn't seem like a software thing to me.
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: Elimination of Torsion on Steel Spandrel Beam due to Curtain Wall Load
You could probably come up with the force components by hand in your kickers......and a good check on that might be modeling it in STAAD (using the offset command and checking it with STAAD's torsion code check option).