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RE: Shear Walls and 3x Framing (UBC)

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Title: RE: DC PE needed (drawings review)

Chuck –

 

Question 1:

Staggered 8d’s at 4” is required/is a problem on a 2 x (for 380 PLF) and 8d’s at 6” is not? Except for the last sentence in footnote 3, it’s not clear that, if the shear capacity is less than 350 PLF that the nailing at the panel edges and sill plates have to be staggered. I thought the footnotes were clearer about nail stagger requirements in the 1994 UBC (footnote 2 required staggered nails when spaced at 2” for all nail sizes and when spaced at 3” for 10d nails).

 

Question 2:

If the anchor bolts are sized/spaced for half capacity and the shear load is less than 600 PLF, a 2x foundation sill plate is acceptable. How is the nail stagger issue resolved in your mind in this case?

 

Unless I’m missing something (which is entirely possible), I thought nail stagger was only required for all nails spaced 2” and for 10d’s spaced at 3” (and closer). The last statement in footnote 3 discounts this, but I’m not sure if it’s applicable for shear walls with a capacity less than 350 PLF.

 

Thanks,

 

T. William (Bill) Allen, S.E. (CA #2607)

V/F (949) 248-8588

San Juan Capistrano, CA

http://members.cox.net/ballense/

-----Original Message-----
From: chuckuc [mailto:chuckuc(--nospam--at)pacbell.net]
Sent: Thursday, December 11, 2003 10:22 AM
To:
seaint(--nospam--at)seaint.org
Subject: Re: Shear Walls and 3x Framing (UBC)

 

The nails need to be staggered & it isn't possible without the 3x at the edges.
Chuck Utzman, P.E.

Schwan, Martin K. wrote:

Bill, in the UBC they say “where allowable shear values exceed 350 plf…” I think it’s clearer in the IBC where it states “sill plates resisting a design load greater than 350 plf (ASD)…”  I always thought the intent was if the design load exceeds the stated value then 3” sill plates are required.

 

-----Original Message-----
From: Bill Allen [mailto:T.W.Allen(--nospam--at)cox.net]
Sent: Thursday, December 11, 2003 7:07 AM
To: seaint(--nospam--at)seaint.org
Subject: Shear Walls and 3x Framing (UBC)

 

According to footnote 3 under UBC Table 23-II-I-1, any shear wall with a capacity greater than 350 PLF in seismic zones 3 & 4 need 3x members at abutting panel edges and foundation sill plates (unless the anchor bolts are designed for half…).

 

According to the table, a shear wall 15/32” CDX w/8d @ 4” has a tabulated capacity of 380 PLF.

 

Question:

 

If I design a structure such that wherever I have a shear wall meeting the above specification the design load is no more than 349 PLF, do I still need 3x members at abutting panel edges and foundation sill plates when my anchor bolts are not designed for half capacity? The concern I have is that, even though I limit the design force in this shear wall to no more than 349 PLF, it still has a capacity of 380 PLF.

 

TIA,

 

T. William (Bill) Allen, S.E. (CA #2607)

V/F (949) 248-8588

San Juan Capistrano, CA

http://members.cox.net/ballense/