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Re: Using Wood-Framed Conventional Construction as a Lateral Shear Resisting ...

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Actually in the scenario you describe, the rear wall would not qualify under Conventional Construction.  The 12' of braced wall from the table is "per 25' of braced wall line'.  Since you have 60' of braced wall line in the rear it will need nearly 30' of braced wall panels instead of only 12'.
 
Gary Grinstead, SE


-----Original Message-----
From: Jnapd(--nospam--at)aol.com
Sent: Thursday, March 6, 2008 4:12pm
To: seaint(--nospam--at)seaint.org
Subject: Re: Using Wood-Framed Conventional Construction as a Lateral Shear Resisting ...

Also along these lines  as Dave was alluding to if your Sds>1.00 and you are trying to use Chapter 23 of the CBC ...Sec 2308.12.4 Braced wall length...Table 2308 12.4 for plywood panels 12' of shear for a Braced Wall Line with each panel at 2:1 ratio. This change will push several projects into engineered design. This will make Dennis Wish a little happier.
The new problem do you design just one wall line ...say at the front of the building???
Because you know that the rear has 12' of Braced Wall panels and 48' of glass and qualifies for Conventional construction.
 
 
 
In a message dated 3/6/2008 11:45:18 AM Pacific Standard Time, davea(--nospam--at)laneengineers.com writes:
Terry,

Unless the building official waives the restriction, loads that are
noted within the conventional construction section of the code are
intended as triggers -- in other words, if your ground snow load
requirement for that area exceeds 50 psf, then you are (technically) not
allowed to use the conventional construction provisions.  You must
complete the design according to Chapter 16, etc.  Some of these
triggers are only applicable to specific seismic regions -- for example,
the restriction of irregular features only applies to SDC D & E
(2308.2.7).  The triggers are not usually a matter of whether wind or
seismic "governs", but rather a matter of WHERE you are (SDC C versus
D).

HTH,

Dave K. Adams, S.E., P.Eng.
LANE ENGINEERS, INC.
979 N. Blackstone Street
P.O. Box 1059
Tulare, CA  93275
Direct Line:  (559) 688-5263
Direct FAX:  (559) 688-8388
E-Mail: davea(--nospam--at)laneengineers.com
Weblog: www.training4engineers.blogspot.com





-----Original Message-----
From: Terry Weatherby [mailto:terry(--nospam--at)wrfed.com]
Sent: Thursday, March 06, 2008 9:58 AM
To: seaint(--nospam--at)seaint.org
Subject: Using Wood-Framed Conventional Construction as a Lateral Shear
Resisting Method fior Design

Hi everyone;
    I have an question which seems to keep coming up year after
year.
    We often have clients who's residential project has been plan
checked by a local building department and one wall line does not comply
with the lateral provisions of 2007 CBC (2006 IBC) Section 2308 for wall
bracing.  Consequently, we do a lateral analysis for this one wall line.
I
assume this is standard operating procedure so, with this as an
introduction, let me get to my question.
    The CBC/IBC Section 2308.2.3.3 says an engineered analysis is
required when the Snow Load exceeds 50 psf.  Most jurisdictions allow a
75%
reduction in Snow Load for Seismic design (yes-it varies by
jurisdiction).
So, if I run lateral calculations to show that Wind Load governs over
Seismic Loads for these heavy snow load areas, can I use the
Conventional
Construction provisions as my lateral shear resisting design/detailing
element OR do I need to run full-blown lateral calculations for the
building
as a whole?
    I am finding more and more that engineering offices are running
full
blown lateral calculations without further discussion.  What does your
office do?

 
Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA




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