Question about top flange joist hanger connections to W shape beams

[cliff234]

I am detailing joist connections to W shape beams. (see attached) In some cases I have joists on only one side of the beam and I am concerned about torsion on the beam. But even where I have joists with equal spans on both sides of the beam there might be live load on only one side. These are commonly used joist hangers, however I don't feel comfortable ignoring the torsion. Two questions: Is it common to ignore the torsion? If not, then how do I brace the steel beam to resist the twist?

 

[KootK]

It is pretty common to ignore the torsion. Particularly as, in many cases, you don't really have torsion resisting connections at the ends of the beam so there's nowhere for the torsion to exit the system anyhow. Every four feet or so I'll detail a strap that connects the lower 1/3 of the joist back too the beam to counter the torsion.

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.

 

[jayrod12]

Make sure you provide wood blocking at the bottom of the joist/steel beam. I've been burnt by this before.

 

[mike20793]

I called and asked about the squash blocks earlier this week and I was told by Simpson that they aren't required because of how it was tested.

 

[Ron]

Ignore the torsion.

 

[jayrod12]

I called and asked about the squash blocks earlier this week and I was told by Simpson that they aren't required because of how it was tested.

Interesting. I'll need to talk to my supplier and clarify

 

[XR250]

I do the strap thing as Kootk mentioned as well. I have seen first-hand where the beam rotated in this situation. I also am not a big fan of the hangers only bearing an 1 5/16" or so of the nailer. Seems like it would be prone something not good happening if the loads are high or there is no sheathing tying things to the beam or if the nailer does not flush out with the face of the beam correctly. I prefer the weld-on or packing out the beam and using face mount hangers.

 

[KootK]

Make sure you provide wood blocking at the bottom of the joist/steel beam. I've been burnt by this before.

I called and asked about the squash blocks earlier this week and I was told by Simpson that they aren't required because of how it was tested.

I have no idea what you guys are talking about which leads me to believe that I may have a past/future problem on my hands. Can either of you expand upon this?


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.

 

[HouseBoy]

KootK,
My guess is this:
Certain metal hangers require that there be a wood block at the end of the beam/joist. "Backer block" might be the better term of this.
USUALLY this is when a top flange style hanger also has nails in the "sides" -OR- when a top flange style hanger is attached to a "I-joist" header.

Many hanger conditions do not require this but it might look "weird" and .... you know how some plan examiners can be...