3x Required at Shear Wall Panel Joints?
3x Required at Shear Wall Panel Joints?
(OP)
In the IBC 2003, Table 2306.4.1 (p.469), footnote i. states that "In Seismic Design Category D, E, or F, where shear design values exceed...[350 plf] (ASD) all framing members receiving edge nailing from abutting panels shall not be less than a single 3-inch nominal member. ..."
My question is this: if wind loading requires a wall with capacity higher than 350 plf (ASD) (and seismic loading does not require over 350 plf capacity shear walls, even though the structure is in SDC D/E/F) is a 3x at the panel joint still required?
Has anyone run into this - how did you handle it?
Thank you!
My question is this: if wind loading requires a wall with capacity higher than 350 plf (ASD) (and seismic loading does not require over 350 plf capacity shear walls, even though the structure is in SDC D/E/F) is a 3x at the panel joint still required?
Has anyone run into this - how did you handle it?
Thank you!





RE: 3x Required at Shear Wall Panel Joints?
RE: 3x Required at Shear Wall Panel Joints?
Often the provisions for seismic are more stringent than for wind.
It's not clear to me in this case.
In my office, we have a table with typical shear walls we use listed with their construction and capacities... If the above IBC 2003 table's footnote applies to both wind and seismic controlled designs, then our table is in error, and we ought to be specifying 3x's at panel joints in several situations that we aren't currently... The reason I was given by a colleague why this wasn't so was that this would only apply if seismic is the controlling lateral force for the direction (wall) in consideration. If wind controlled, a 3x at the panel joint wouldn't be required at this "350plf(ASD)" cutoff point.
Any comments on which is true/used are most appreciated!
RE: 3x Required at Shear Wall Panel Joints?
I usually don't spec any shear walls that require 3x because it is not available locally, so the contractors will use 2-2x's. That opens a whole different can of worms, so I just avoid it. Not always, but 10d @ 4" is what I normally spec for shear walls. I will add walls until this works, or I will use steel frames.
RE: 3x Required at Shear Wall Panel Joints?
It was just pointed out to me that IBC 2003 Section 2306.4.1 says that the IBC table values may be increased by 40% for wind...so that would make the cutoff for a 3x at the panel joint for wind controlling be at 1.4*350= 490 plf which is a little better for my current design - doh! However, for wind or seismic, we haven't been putting a 3x at the panel joint in several of the situations that table footnote implies we should. But apparently you can ignore the table and it's footnotes completely if you "calculate by principles of mechanics...by using values for nail strength given in the NDS and wood structural panel design properties given in the APA..." as 2306.4.1 states...
RE: 3x Required at Shear Wall Panel Joints?
However, in the 2006 IBC, the 2-2x in lieu of 3x at a panel joint has been adopted from the APA Techical Topic on the same subject, which gets rid of some 3x's. Watch the 3x sill requirements, though...you can get away from a 3x sill for applied loads over 350 plf but less than 600 plf (in your sill, not your wall) if you provide enough anchor bolts.
Of course, if your project is not in these higher Seismic Design Categories, you don't have to worry about all this!
RE: 3x Required at Shear Wall Panel Joints?
RE: 3x Required at Shear Wall Panel Joints?
RE: 3x Required at Shear Wall Panel Joints?
Mike McCann
McCann Engineering