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RE: IBC 1617.6.2 & IBC 1617.6.3--1997 UBC 2320.2 & 1605.2 - how t o tell if your plan reviewer is really looking at the plans

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Dennis:


I was wrong on a few points about the IBC in my diatribe about UBC
requirements design of portions and combination of R's on the same axis.
IBC 1617.6.2 & IBC 1617.6.3 allows you to vary R's from grid to grid for
houses and duplexes.  Also IBC 2308.12 says you can design a portion of an
unusual house.  If it is the local code down there - more power to you guys.
I would consider that if someone brought it up on one of my permits.
Personally my loyalty is toward the profession and not toward enjoying the
thrill of ruining a person's day.

On the flexible diaphragm thing: FEMA 368 Section 5.2.3.1 and FEMA 302
Section 5.2.3.1 say that wood diaphragms on light frame walls should be
considered rigid. I once got chewed on by someone on your list for
suggesting that I had never seen a wood building design using rigid
diaphragms. I've seen that LADBS Document P/BC 2001-03 that saysou could use
the "simplified static force procedure" and assume flexible diaphragms until
other research comes out.


The problem with prescriptive methods, locally at least, is that nobody has
ever bothered to understand the code provisions and most people think that
prescriptive design =no design & nothing shown on plans.  There are specific
layout rules and the stuff should be shown on plans.

The problem with the new IBC [not IRC] code language is that it says
buildings of unusual shape can have the unusual area designed. 97 UBC
2320.5.4 said design the entire building if it is irregular, and UBC 2320.2
"design of portions" was meant to apply only to regular [not irregular]
buildings where grids do not have enough bracing ect... The end result is
you are moving towards everything = prescriptive = no design.  It leaves the
opportunity for  dumb ideas like: if I have cantilevered columns on the
first floor can I design them for the capacity of two gypsum board
shearwalls because that is all that is required for a prescriptive house.

The IBC puts the onus on the BO to prove that a building is not prescriptive
and to prove when an unusual shape exists and then to argue that one part
has to be designed.  This stuff should be considered before a permit is
applied for and it never is here.




Respectfully,
Scott Haan



-----Original Message-----
From: Dennis Wish [mailto:dennis.wish(--nospam--at)verizon.net]
Sent: Sunday, February 10, 2002 1:08 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: 1997 UBC 2320.2 & 1605.2 - how to tell if your plan
reviewer is really looking at the plans


Scott,
You do accept the design of residential structures by prescriptive
methods if I recall correctly from a thread we had a long time ago. What
rationale is there to argue and debate the engineering design that
reduces the R of the entire structure in the direction of loading to the
lowest R based on the most flexible resisting system used, if the same
building can be "tweaked" and all holddowns eliminated per the
prescriptive approach?

Dennis S. Wish, PE
California Professional Engineer
The Structuralist.Net Information Infrastructure

Website:
http://www.structuralist.net

."The truly educated never graduate"

-----Original Message-----
From: Haan, Scott M. [mailto:HaanSM(--nospam--at)ci.anchorage.ak.us]
Sent: Saturday, February 09, 2002 1:36 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: 1997 UBC 2320.2 & 1605.2 - how to tell if your plan
reviewer is really looking at the plans

Try asking the plan reviewer if she will accept base isolation as an
alternative to R=2.2 for cantilevered columns.  Then on the next set of
plans you submit delete all the anchor bolts off the plans and details.
If
the permit gets approved then you will know that the BO is not looking
at
the plans.

If that doesn't work anonymously drop off a big plate of ex-lax brownies
at
the Building Department.  BO's, as a general rule, have a real soft spot
for
baked goods.



-----Original Message-----
From: NDZ28(--nospam--at)aol.com [mailto:NDZ28(--nospam--at)aol.com]
Sent: Saturday, February 09, 2002 12:05 PM
To: seaint(--nospam--at)seaint.org
Subject: Fwd: 1997 UBC 2320.2 & 1605.2


Does anyone know if any building department has been accepting the
Seismology
Committee's opinion on the use of cantilever steel columns?  In the Los
Angeles area, I have been asked to comply with the least value of R
along
the
same axis per 1630.4.4. No exceptions.

Thanks
Andy




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