Relative Stiffness of OSB Sheathed wall to Gypsum Sheathed wall

[EngDM]

Hey all,

Does anyone know of a good resource to figure the stiffness of these walls? I am trying to determine how much of the lateral loading will be taken by walls running parallel to eachother, under rigid diaphram assumptions. I thought RISA 3D would have a gypsum option and I'd just compare deflections under unit loads for different slenderness levels of wall, but it doesn't seem RISA can do gypsum walls.

CSA O86 allows you to restrain up to 40% of the lateral load with gypsum walls, but I was wanting to check if the stiffness even attracks 40%.

 

[ChorasDen]

The 2021 SDPWS gives a Ga value for gypsum wallboard sheathed shear walls depending on the installation direction of the panels, see commentary table C4.3.4A

 

[EngDM]

The 2021 SDPWS gives a Ga value for gypsum wallboard sheathed shear walls depending on the installation direction of the panels, see commentary table C4.3.4A

I'm trying to find a similar table in the CSA code but without any luck. I do not have access to the SPDWS; the free viewer online has super blury tables of these. I also couldn't seem to add a custom nail pattern to RISA either, or edit the Ga.

 

[ChorasDen]

the free viewer online has super blury tables

The viewer is an i-frame of a .pdf of the reference standard, so you should be able to easily zoom in and increase readability.

 

[phamENG]

Make sure you're not zoning your browser. That makes it blurry. Zoom with the viewer's internal zoom buttons.

 

[lexpatrie]

Early on the relative stiffness of the two is fairly comparable, the gypsum gets damaged earlier in the loading, however. That's why you're not supposed to "mix" gypsum board shear walls and plywood/OSB on the same wall.

That bit about the internal zoom, phamENG, that's really helpful. Thanks. I never saw that, had the hardest time reading things and even emailed them about it. Got no reply.

For convenience to others - like to the lateral chapter of the 2021 SDPWS.