Staggered Stud Shearwalls 1

[davidfi]

I am working on a new 3-story woodframe project where the architect wants to use staggered stud walls for the exterior walls and corridor walls.

The exterior would be a 2x6 and a 2x4 staggered on a 2x8 plate. The corridor will probably be a 2x4 and a 2x4 on a 2x6 plate. Has anyone used staggered stud walls for shear walls? I am concerned about the inability to install blocking for panel joints and strapping. Also, would one edge of the stud be unbraced because there is only sheathing on one side?

I am interested to hear about any experiences others have with staggered stud shearwalls.

Thanks!

 

[jdgengineer]

I typically consider the stud to be unbraced in weak axis in these instances. If there is a bearing load of substance on the wall you may need 3x studs rather than 2x.

Blocking is a concern as well as you mention. Seems like you would want full height plywood to avoid the splice issue.

 

[jayrod12]

Full height plywood is not typically an option, since it's supposed to be installed face grain horizontal, that being said, your blocking doesn't need to be full depth of studs. Therefore you could probably have the blocking installed 2x4 on flat. Many shearwalls I design end up being unblocked, there's a reduction in capacity but many times it can still be adequate.

 

[dik]

Stud spacing @ 12"? One consruction for insulation and the other for sound proofing? You should be able to run your plywood sheathing horizontally. If corridors are not used for lateral, then you should be able to use drywall... maybe 5/8" for 24" spacing?

Dik

 

[Celt83]

For axial compression sheathing on one side can be considered to brace the stud short face (NDS 2018 - A.11.3 pg. 159 in PDF)

For negative pressure on the wall panel the stud should be treated unbraced for bending which will impact the CL factor.

For shear I have looked at these as single side sheathed only in the past, but a load path exists to rationalize accounting for both faces since the studs share top and bottom plates.

WoodWork's Expert Tips Post on staggered stud wall Slenderness

WoodWork's Expert Tips Post on blocking

American Wood Council Fax on Blocking Orientation

Open Source Structural Applications:

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

 

[JAE]

You can add horizontal blocking at designated spacings up the studs to help laterally brace each stud for axial or bending....axial maybe not that important based on Celt83's reference.
Ensure that blocking is nailed to sheathing as well.

The studs and blocking, holdowns, etc. can all be installed first, then the sheathing to finish off the wall.


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[KootK]

I certainly wouldn't sweat the blocking for axial load bracing. Lots and lots of load bearing partition walls are only braced on one side by sheathing.

If you install blocking take care that it doesn't compromise the sound isolation that you're architect is going for in the first place. Any blocking that connects the studs on both sides of the wall has the potential to do that. 2x on the flat with 1/2" gap between blocking and opposing stud would probably be ok.





I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.