2x6 tall wall studs for 16'H garage 2

[TroyD]

For tall wall 2x6 studs, is consideration ever given for the 7/16" OSB sheathing (outside face) and 1/2" GB (inside face) for resisting bending from out-of-plane C&C wind loads? I have a residential client who is building a 52'Wx90'Lx16'H garage/shop. 35 psf roof balanced snow, trusses at 24" o.c. Stud height is 15'-7_1/2". I modeled the stud in WoodWorks using a 2x6 SFP No.1/2. It does not satisfy the combined axial compression and side load bending criteria of AWC NDS equation 3.9-3. (see attached WoodWorks output). Obviously there are a few options: tighter 12" o.c. stud spacing, higher grade lumber (or LSL studs), 2x8 studs, or double 2x6 studs at 24" o.c. aligned with the roof trusses. I'm thinking that the column stability factor, Cp, of the stud should be higher. Any input is appreciated.

 

[JAE]

Somewhere out there are statements I've seen about the composite behavior of studs and plywood but we've not ever relied on it - just seemed to tenuous.

I think you are stuck with the other options you listed.

 

[XR250]

I would go 2x8 studs 24" o.c. under the trusses (if that passes) and then 2x6 on the lightly loaded walls.

 

[Huevo]

You can use Cr = 1.35 for 2x6 studs if you meet the criteria listed in SDPWS §3.1.1.1

 

[Celt83]

Is your 27 psf an ultimate level wind pressure, fb looks like it is 0.6x the bending stress from 27 psf.

If 27 psf is ultimate I get the same answer as woodworks, bit more detailed results from my end:

At 16' tall pay attention to to temporary construction bracing. Looks like 12"o.c. works but at that height may be worth suggesting LSL's to make sure your actually getting straight studs in the wall.





Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[Aesur]

I would stick with 12" spacing unless they can go to 2x8's (assuming they work). Another thing to look at is out of plane deflection, I just finished designing a 18' tall garage of similar construction but no snow loading and ended up with 2x6 at 12" o.c. (which was deflection controlled). The owner wasn't very happy that the original draftsperson, hired to do the project under the IRC, had specified 24" o.c. which got rejected and required a structural engineer. Note that for deflection the limit depends on the finish for the garage, around here it's typically stucco which ends up being L/360 which I doubt most houses/garages designed using IRC actually meet. It is worth noting that using C&C wind loading you can use 0.42 C&C for deflection calculation, something that many engineers don't consider when using EnerCalc or other programs to design for wind, this will help some as the LC in your calcs was 0.6D + 0.6W for deflection.

 

[mbullism]

I'm sorry, but spruce-pine-"fur" struck me funny

Analog spoken here...

 

[Celt83]

adds to the R-value for the wall.

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[msquared48]

Just use a 4x6 at 24.

Mike McCann, PE, SE (WA, HI)