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Re: 2003 IRC Brace wall lines

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Martin,

Thanks for your reply.  Once again, I wasn't as clear as I maybe should have
been.  And, I sent the message from the office between calls etc. etc. and
just didn't take enough time writing the message (I've got to work on this
writing thing).  Even with the 8 methods available in the IRC I'm fairly
certain (from the perspective of an arm waive initially looking at the
plans) that I will have some locations where the 8 possibilities won't work.
That is, if I were to do an actual lateral analysis (per IBC) and try to
compare those requirements with the "working backwards" capacities of the 8
possibilities from the IRC none of the capacities of the 8 possibilities
would work.  Does that make sense?  I am having a problem with the
prescriptive "allowable" wall types in the IRC as compared with calculated
loadings from a "full blown" wind analysis (or seismic).  And, I am fairly
certain from my experience in my new location, that I will be (maybe too
pessimistic) that I will be raked over the coals if I require anything more
than the prescriptive requirements.  Is there any code provisions for size,
complexity, layout, etc. that would tell me that the prescriptive wall types
can not be used, and a full wind (or seismic) analysis is required per the
code?  If there isn't I'll just have to fight my battle on this one, but I
was hoping for some code help to explain to the client.  Again, I'm fairly
new to the IBC, IRC.  Is there such a thing as "code help" with the IBC? :-)

If that didn't make sense, I'm quitting for the night, going for another
cocktail and my new novel.

Thanks again,

Joseph Grill, PE (Structural)


----- Original Message ----- 
From: "Schwan, Martin K." <SchwanMK(--nospam--at)ci.anchorage.ak.us>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, April 26, 2004 5:11 PM
Subject: RE: 2003 IRC Brace wall lines


Joe, See table R602.10.1 in the 2003 IRC and sections R602.10-R602.11.3.
There are 8 methods for braced wall panels listed in section R602.10.3.
Table R602.10.1 indicates where the various methods can be used with
respect to seismic design category and level.  I have not gone too far
into this because we are still using the 2000 IRC.  The 2000 IRC had two
braced wall types (see section R603.8); type I is the more traditional
braced wall with no openings and holdowns on each end of each braced
wall.  Type II has openings with holdowns at each end (like the
perforated shear walls).  I do not see the type II in the 2003 IRC,
however.  We use the provisions in chapters 16 and 23 of the IBC.  In
the 2003, check out 2308.9.3 and figure 2308.9.3 for example. HTH


-----Original Message-----
From: Joe Grill [mailto:jgrill(--nospam--at)swiaz.com]
Sent: Monday, April 26, 2004 3:24 PM
To: seaint(--nospam--at)seaint.org
Subject: 2003 IRC Brace wall lines

The area I am working in has adopted the 2003 IBC and IRC.  Are there
any
provisions that tell us where you can not use the Wall Bracing
provisions in
the IRC for lateral?  I am starting to look at the lateral on a
residential
project where the roof diaphragm is pretty broken up with differing
elevations.  I know that I will be asked why the provisions in the IRC
for
wall bracing won't work.  I can't find any provisions myself, but may be
looking in the wrong place.  Also, are there any Q&A materials out there
for
the IRC and in particular the wall bracing provisions?  I have one for
the
IBC.  To me the provisions in the IRC are pretty confusing, and I've
never
had to really look into them.

Thanks,

Joe Grill


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