Minimum Length Wood Shear Wall Panels

[smokiibear]

Any fellows know of a requirement for standard segmented wood shear wall minimum panel lengths?

I thought it was 24", but cannot for the life of me find that requirement in current AWC (NDS/SDPWS) or IBC/IRC.

Thanks,

 

[jerseyshore]

I think the IRC/IBC limit the minimum length to 24", but NDS just says that the minimum length is based on the max aspect ratio.

 

[phamENG]

Well for an 8ft wall a 3.5:1 AR is 27" or so. So 24" is probably a good hard minimum. If you want to use a portal frame, APA has a paper giving capacities for engineered applications down to 16".

 

[smokiibear]

Thanks for the link, phamENG.

What I was after is the minimum length of panel in a shear wall. So, if you have a 18" panel at the end of a 9.5' shear wall, is that ok. or, do you need the shear panel to be 24" minimum length along with (1) 48" panel and (1) 36" panel?

I believed there used to be a minimum requirement of 24" panel sections. For instance, in SDPWS 2021, diaphragms require a 24" panel or framing and blocking. So, that's almost a minimum panel length, but with exception.

 

[phamENG]

Ohhh. You mean minimum width of the last sheet of plywood. I suspect it doesn't really matter so long as the nailing is correct. I don't recall ever coming across a limit. The strength of the panel doesn't change with size.

 

[smokiibear]

Yeah, I wouldn't think so, especially with the listed requirement for diaphragms. They just want edge nailing. I just thought I came across it before.

there are references to 2' pier lengths for FTAO walls, and for IRC Braced Frame Walls...but I do understand those are different animals.

Indecently, in my search for this, I came across FTAO walls allowing doors/openings at bottom of wall so long as a chord can be provided. I had never seen that before...and always skipped over door openings for a segmented shear walls instead. Doors wouldn't really work on a slab since there really isn't a chord at the bottom of the wall (unless you could say the concrete acted like a chord).

Well, off topic for sure, but found that interesting and hadn't seen that for years.

 

[smokiibear]

Also, I did come across this which may be cause for my previous thoughts, as I started under the 97 UBC. It wasn't a requirement, but recommendation:

 

[jerseyshore]

An older AWC document about perforated shear walls says: "The minimum length is tied to the minimum aspect ratio, h/L, requirement in the governing building code. In most cases, this ratio is 3.5/1..."

 

[smokiibear]

The AWC SDPWS 2021 still requires that ratio is 3.5/1 for h/L.

 

[jerseyshore]

Correct, but the document I referenced just highlights what I said above that the minimum length is dependent on the aspect ratio, not a set number.

 

[phamENG]

FTAO walls allowing doors/openings at bottom of wall

While technically permitted, I wouldn't. There's a good research paper out there somewhere that compares several analytical methods to destructive tests. Diekman, which does not allow doors, was the most accurate. All door opening specimens were significantly weaker than expected.

 

[DoubleStud]

I think maybe you were referencing IRC R602.10.7

 

[smokiibear]

While technically permitted, I wouldn't. There's a good research paper out there somewhere that compares several analytical methods to destructive tests. Diekman, which does not allow doors, was the most accurate. All door opening specimens were significantly weaker than expected.

I totally agree.

I think maybe you were referencing IRC R602.10.7

I defintiely wasn't thinking of IRC/CRC here in Kali...but that obvioiusly reveals a "best practice" not explicitely stated in the SDPWS.