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Re: Wood Shear Wall Studs < 2x4

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In a pure shearwall sense, is there concern that 2x3 walls would perform noticeable less than 2x4 walls? I say this just off the top of my head, because the mechanics of a shear wall is generally that of a short beam with deflections controlled by shear deformation and fastener/wood interface contact deformation, plus the hysteresis of the interface friction (a proper PhD could parse that better, I'm certain).

Looking only at the components that matter, the end studs and sheathing control as long as there is sufficient penetration of the fasteners to achieve their single shear rating.  You might need an extra stud at the ends for compression/tension, and to look at the shear interface at the plate. Otherwise I would expect similar performance to 2x4s.  Thinner studs, as Barry pointed out, result in more difficult connections (and field tolerances/missed studs).

I presume this is for an interior wall, as 2x3s are not allowed prescriptively on exterior walls and it would be a mighty short wall to make them work by the numbers.
Jordan


Tom Skaggs wrote:

Aware – yes in manufactured housing industry.  2x3 studs are not uncommon.  I’m also aware of adhesive used between 2x3 studs and drywall to increase racking strength.  The factory quality control in this business allow for other than typical details.

 

In general, APA has not done tests on smaller than 2x4 walls, and I’m not aware of shear walls being construction for site built construction with less than nominal 2x4s.

 

In addition, some prefabricated shear walls that are sheathed with wood structural panels have finished thicknesses of around 3-1/2”, thus implying that studs are approximately 3” deep.

 

Tom

-----------------------------------------------------------------------
Thomas D. Skaggs, Ph.D., P.E.
Senior Engineer
APA - The Engineered Wood Association
7011 S. 19th Street
Tacoma, WA 98466
ph: 253/565-6600
fx: 253/620-7235
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From: Robert Kazanjy [mailto:rkazanjy(--nospam--at)gmail.com]
Sent: Tuesday, July 25, 2006 15:12
To: seaint(--nospam--at)seaint.org
Subject: Re: Wood Shear Wall Studs < 2x4

 


From: Barry Welliver [mailto:barrywelliver2(--nospam--at)earthlink.net]
Sent: Tuesday, July 25, 2006 3:37 PM
To: Seaint Listserv
Subject: Wood Shear Wall Studs < 2x4

Anyone aware of information regarding shear wall construction with studs less than 2x4?


check out the modular home / mobile home industry

Maybe APA has some info

as long as you can properly develop the sheathing nails, the shearwall should have reasonable capacity......just don't expect to use heavy sheathing (1/2 or thicker) & aggressive nail schedule (4/12 or 3/12)

a number of years ago we built a 1/2 scale structural we affectionately referred to as the "brick dog house"

We cut down framing members to 1/2 size "2x4" & "4x4"......... actual size .75 x 1.5   & 1.5 x 1.5
we also made some miniature HD's as well

We "nailed" the whole together with Senco N series staples  (16 gauge;  .0625 wire dia) Nailing schedule was  6/12.   We used 3/8 ply.   I think the thing was about 4' wide & 6' long & 4' high (I'm recalling dimensions)

we mass loaded it with about 2200 lbs of steel at the ceiling diaphragm

we tried our best to fail this thing on our shake table...even at acc of ~1g we couldn't break it.  We had to go back in & remove every other staple.....finally we fatigued the thing with repeated "fling" type input

A full sized wall (approx 8 x 8) constructed of undersized framing members wouldn't have the extreme stiffness of our "dog house" IMO because of scale effects but it would have considerable strength.

IMO the weak link / failure point would be framing members splitting from sheathing nailing; even a 6d gun nail is .113 dia..... a little big to be face nailing into a .75" member (that's why we used the staples)

cheers
Bob

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