Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Alternate Braced Walls and SDC D

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Gary,

Well, you got one "no" vote; I'll give you a "yes, with one
qualification". (Maybe two--I haven't read the CBC amendments
extensively.)

My read is that the two options for an alternate (narrow) wall bracing
panel can be used in SDC D, provided the total amount of bracing on the
wall line is not less than the amount Table 2308.12.4 requires.

So, for example, take a wall with three standard 48" panels on a
dwelling with Sds between 0.50 & 0.75. The total standard bracing is
12'-0", which exceeds the minimum 8'-0" required by the table. If you
replaced one panel with a 32" alternate, you'd still have a total of
10'-8" of bracing and be above the minimum requirement.
 
The alternates are permitted to exceed the aspect ratio limits in
footnote "a" via the standard equivalence clause. The design for the
alternate panels is based on testing which compares the performance of
the narrow panel to the performance of a typical 2:1 aspect ratio
segment. The testing shows that the alternate panel performs equal to or
better than a standard segment in strength and stiffness. (In fact, I
think the overall body of testing shows the various narrow wall segments
perform better than the standard 48" panels.)

Gary

Gary J. Ehrlich, PE
Program Manager, Structural Codes & Standards
National Association of Home Builders (NAHB)
1201 15th Street, NW, Washington, DC 20005
ph: 202-266-8545  or 800-368-5242 x8545
fax: 202-266-8369
gehrlich(--nospam--at)nahb.com
-----Original Message-----
From: garyg(--nospam--at)structuralstuff.com [mailto:garyg(--nospam--at)structuralstuff.com] 
Sent: Saturday, December 08, 2007 7:01 PM
To: seaint(--nospam--at)seaint.org
Subject: Alternate Braced Walls and SDC D

I've read section 2308 of the 2007 CBC several times not and still
cannot make up my mind on whether or not alternate braced walls are
permitted in SDC 'D'.  I'll read in once and think 'no way' but then
another reading has me thinking 'maybe' until another reading has me
back to 'no way'.

If they ARE permitted I don't think it will be the same as under the
2001 code since table 2308.12.4 places requirements on total braced wall
length.  If they are not permitted, I can see garages as requiring
engineered shearwalls regardless of how the rest of the house is
designed.

Any thoughts will be appreciated.

Gary Grinstead, SE
Stockton, CA


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ******** 

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********