TEK Screws Through (3) Layers Of Sheet Stock

[BSVBD]

Designing an X-Brace Shear Wall for a CFS stud penthouse with narrow endwalls. One endwall has a door in it!

Lateral load must transfer through top trak to gusset to diagonal X-Strap.

Are TEK screws effective through (3) layers of (16 gage) sheet stock?

Provided I have (3) thread pitches beyond grip, for length, can I still use 14 tpi rather than 24 tpi?

Below, the first snip is from Clark-Dietrich. The second snip my actual situation with a rather steep strap angle. The number a screws in second snip is preliminary.

I'd prefer to design each transferring element with only (2) layers, but, i don't know, at this time, if i can do it?

Thank you!

 

[XR250]

You need to check the drill and tap capacity AND the max material attachment.
A #10Tek3 has 0.175" drill and tap capacity. 3 Layers of 16ga = 3 x .054" = .162". In reality, it may be thicker as .054 is the design thickness and not the actual thickness. Plus you will have some gaps between the members. A #12Tek3 has a .210" drill and tap capacity so it will might do the trick.

 

[sturr]

If this only occurs in a few locations you might consider using a very wide strap and omit the gusset plate. A wide strap can attach to the track and studs. I am assuming wind loading controls the design, not seismic.

 

[wannabeSE]

I'd call ITW Buidex (TEKS screw mfr) to see if there are any problems with the screws pulling all the layers together.

On another note:
Per AISI 213 - Lateral Design, the chord stud design needs to consider joint flexibility and end moments when the wall's height to width ratio exceeds 2:1.

 

[XR250]

I'd call ITW Buidex (TEKS screw mfr) to see if there are any problems with the screws pulling all the layers together.

AFAIK, Tek screws will not pull plys together unless one it thicker than the other so it can strip the thinner layer. Usually, the framers will put clamps on these prior to screwing and that is the best you are gonna get for ply to ply contact.

 

[structSU10]

AISI 213 gives a max aspect ratio of strap walls of 2:1 unless you include special considerations in your analysis. Also, the strap looks very inefficient with such a steep angle. Can you make it a sheathed, perforated shear wall?

 

[XR250]

Also, a light gage gusset is only needed to spread the load out to more fasteners. But there is no free lunch. It causes weak axis bending in the top track and the jamb studs. this needs to be checked as well as the connection of the jambs to the top track. I don't do load bearing CFS design anymore, but when I did, I did not uses gussets. I just used a heavy top track and strap. This avoids the pitfalls I just mentioned by keeping things concentric.