Why can't NDS Table 4.2B for High Load Diaphragms be used for shear walls?

[Engineerataltitude]

I can't find any information as to why the shear values for diaphragms in the NDS SDPWS Ch 4.2 for High Load Diaphragms can't be used for shear walls. As long as the underlying framing and nailing patterns are what is required for use of the values in that table, what is the difference whether the sheathing is applied horizontally or vertically? Isn't shear just shear? Is it because horizontal diaphragms typically have all four sides attached to boundary elements and shear walls typically only have two? I was trying to rationalize why that might make a difference but really, the way shear works that shouldn't matter.

I contacted AWS technical support to ask and the response I got was:
" The diaphragm tests are not subject to the same gravity load as the shear wall tests, so it’s not an apples to apples comparison."

Any idea what gravity load shear walls might be subjected to that horizontal diaphragms would not? How much difference could the gravity weight of a vertical shear wall make to it's shear strength?

Can anyone help with understanding this question about using horizontal diaphragms values for shear walls?

 

[JoshPlumSE]

Vertical dead weight in the plane of the wall. Contributing to stability or P-Delta / 2nd order effects on elements within the wall.

 

[EngineeringEric]

you must have rather high shear demand if going down this avenue, i'd recommended more walls or steel

I can see the gravity of the system effecting your boundary elements, load sharing of studs/sheathing/nails, stability of the members within the wall including the field, and maybe some second orders i cannot even fully understand at this hour today.

 

[Engineerataltitude]

So my thought was to look at the shear value differences of 1/2" Struct 1 ply with equivalent nailing and blocking between the diaphragm tables and the shear wall tables and calculate a factor that represents the difference between the two. Apples to apples so to speak. This could account for the differences in testing, load combinations, etc. I could then apply that factor to the values in Table 4.2B to get a reasonably safe shear value to use for a single sided shear wall sheathed with 5/8" Struct 1 ply. That seems defendable doesn't it?

I have a retrofit application for which sheathing on both sides of the wall would be primitively expensive, (cabinetry, plumbing, etc. on opposite wall). Need a 6 ft long, 8 ft tall segment of wood framed wall to deliver 1118 lb/ft of shear strength (ASD, seismic). NDS Table 4.3A for shear walls gives up single sided ply sheathing at 870 lb.ft (ASD, seismic)

 

[XR250]

I have ended up using tube steel frames with a diagonal in these situations. You must have quite a collector top and bottom to get the load in and out.

 

[Engineerataltitude]

True, but no different than what would be required if the wall was to be retrofit with sheathing on both sides, which is commonly done. All those connections would have to be retrofit to match, collectors included. I'm just looking for a singled sided option rather than a two sided option.

I think I'm just going to with single sided 5/8" Struct 1 sheathing with high load diaphragm 10d 2 row nailing (they only need 1 1/2" min embedment in framing to be effective) with retrofit wall studs, bottom plates and collectors. I think that will fly. With modification factors that wall should have a shear value of v = 1180 lb/ft (ASD). Just what I need.