Need help on SDS screw capacity calculations (TJI Joist)

[klukmvp]

I need help finding the SDS screw capacity calculation (attachment below). Also, is there any 4x ledger effect on screw capacity? Thanks

 

[jayrod12]

Is 1/2" of embedment into the studs enough? Doesn't feel that way to me. As long as you specify screws long enough to get the minimum penetration into the studs, then I don't see the 4" ledger having any negative effect on screw capacity.

 

[ChorasDen]

Agree with Jayrod, think the 4x_ ledger is a bit much, I would consider an 1.75" LSL ledger that matches the height of the TJI roof joists. That gives you more room to work with the SDS screw length. I've never liked installing screws into the narrow edge of studs, I'd either use a post at this location to attach the ledger, or if this is existing construction, install blocking between the studs that is attached positively to the studs and then SDS into the blocking instead of the studs.

 

[jayrod12]

Or let in the ledger into the studs so the vertical load is actually transferred in bearing as opposed to relying on the screws.

 

[ChorasDen]

Ah, missed it on first glance, but now I see why you drew a 4x_, for the twist strap to restrain the parapet out of plane load. There are alternate options that can be used instead of a twist strap.

How is this detail getting roof diaphragm load into the actual shear wall sheathing? I'd have to think a bit more on if I am comfortable loading a couple SDS screws in the narrow face in weak axis bending of the studs.

 

[klukmvp]

Actually, I sent a project with this typical detail (also before on some previous projects as usual but didn't have to submit any calc for this), but now city sends structural comments including SDS screw calculation manually

 

[ChorasDen]

SDS is a proprietary product, so you'll need to reference the Simpson design manual for capacities and minimum penetration requirements.

 

[klukmvp]

I had one sample calculation, should it be similar to this hand calc?

 

[ChorasDen]

Refer to the Simpson connector manual. What is the capacity of a single SDS screw with 0.5" of penetration at the applicable Load Duration? My guess is the value will be 0lbs, but you'll need to check with Simpson to confirm.