cold formed steel joist blocking

[gte447f]

What is the best way to handle blocking between cold formed steel floor joists?
1) Blocking shallower than joists so that blocking will fit between the flange returns of the joists and blocking can be installed joist web to joist web, or
2) Blocking same depth as joists and one end of blocking coped to fit between the flange returns of the joists and blocking can be installed joist web to joist web, or
3) Blocking same depth as joists and installed joist web on one end and to toe of joist flange on the other end w/ an extended leg on the clip angle.

See the attached detail for reference. I have seen this detail or similar reprinted many places, but they never address the issue of attaching the blocking to the open side of the C-shaped joists. If the blocking is 2" shallower than the joists as stated in the detail, then attaching with a 2x2 clip angle is fine, but what would you do in the case of full depth blocking? Cope the blocking and use a 2x2 clip angle, or cut the blocking flush and use an extended clip angle?

 

[EngJP]

If you are considering option 1 (shallower depth blocking), I assume that you do not need the blocking to increase the diaphram capacity for plywood decking since the blocking will not be tight to the deck. Do you need the blocking to act as bridging? If so, Simpson Strong tie makes 20 ga bridging that would probably be cheaper. If you are providing blocking to support the top of a stud wall running parallel the joists, I would choose option 1. If you are trying to decrease your unbraced length, I would choose option 1 also.

 

[gte447f]

EngJP, my original intent was to provide lateral/torsional bracing for the joists at supports to keep them from rolling over, but now I think I need the diaphragm connection also. I am thinking full depth blocking will be required. That being said, which is a better connection at the open side of the C-shaped joists, coping the blocking or using an extended clip angle, or is there another option I am not thinking of?

 

[EngJP]

I would go with the extended clip angle to avoid coping the blocking.

 

[shobroco]

Pieces of joist (i.e. same depth blocking) with extended clip angles will be fastest, cheapest, and cover most possible scenarios for loading.

 

[a2mfk]

Since you likely have a standard detail of each way (or can download one for free from the manufacturer), you can always put both on the drawings and let the sub pick the one he likes.

Its been a while since I looked at CFS details but I think some manufacturers have pre-fabricated connections for this application.