×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Elimination of Torsion on Steel Spandrel Beam due to Curtain Wall Load

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.

RE: Elimination of Torsion on Steel Spandrel Beam due to Curtain Wall Load

Your strategy will effectively eliminate torsion on the spandrel which is a good idea. With regard to resolving the forces, why don't you post a free body diagram that we can critique for you? Basically, you've got a truss to the left of the spandrel and a roll beam to the right.

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

That's not that far off from what I have done to eliminate torsion in beams I have done. You are going to have to follow the load path and see what sort of displacements happen by compatibility. In other words: like it or not, the W16 (or whatever) will move creating a rotation displacement in the W30 that would need to be accounted for. (Sort of a compatibility torque......for the lack of a better way to put it.)

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).

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources