Joist Staggering 2

[EngStuff]

This isn't project specific, I looked throughout the site and all over, I only found one thread which someone suggested to stagger joists on a particular project.

My question is more of besides constructability and maybe the CG being annoyed about it. Assuming we have a roof with a steel girder which has steel joists on the right of it spaced 6'-0 on center. Joists on the left spaced 6'-0 o.c. but the right and left joists are staggered from each other about 3 feet away. If torsion on the beam was not a concern or taken into account. Would we have any other issues we have to deal with? As in diaphragm design or force transfers. I myself don't see an issue, but doesn't hurt to see what everyone else thinks about this? Perhaps I might not see something that could be an issue.

 

[jayrod12]

Welders are more expensive than labourer's to put bolts in. and yes, it is faster to bolt them. This is the preferred method by the contractors we typically deal with. Bolt if possible, weld if necessary.

 

[XR250]

Interesting - may be location specific. I rarely see bolted bar joists.

 

[BAretired]

That's interesting, lot's of opinions about welding versus bolting. I never considered bolting an option before I retired, but in many ways, would prefer bolts. Is it always necessary to use 3/4" dia. bolts, even for joists? Seems to me that 1/2" dia. bolts would likely be adequate in most cases and would reduce the amount of flange removed. That is perhaps not very significant, and I agree with KootK that Fu can be used instead of Fy for a short distance equal to the bolt diameter. For G40.12 steel, that usually means no reduction for bolt holes.

BA

 

[jayrod12]

Our standard spec is 1/2" bolts minimum. Two per end. Final connection details by supplier.

 

[EngStuff]

Thanks all,

The information received is very useful!

 

[Ron]

Staggering or offsetting joists is a constructability nightmare. It will lead to decking layout and welding issues (mostly missed welds). Most lighter joists require a minimum of 2-1/2 inches of bearing on steel, thus you need 5" plus a little play so 5-1/2 inches is a reasonable minimum flange width. For heavier joists, bearing minimums can go up to 4" so wider flanges would be necessary.

 

[phamENG]

XR250 - I think it is regional. I'm VA/NC and bolts are an erection aide only unless you're getting into joist girders. For K joists on steel beams, I've never seen a final detail that wasn't welded.

 

[XR250]

I'm VA/NC and bolts are an erection aide only unless you're getting into joist girders. For K joists on steel beams, I've never seen a final detail that wasn't welded.

I'm in the same region - hence our similar experiences