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

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Scott,
I absolutely agree with you as far as the prescriptive methods of
design. A lot of your concerns are being addressed in the 2003 IBC which
will be the IRC, however, the root of all of the issues will not be
resolved - how do you educated a designer or builder as to the
interpretations of the prescriptive method when few of them own or have
read the building code section.
Most rely upon a rudimentary plan review where the technician (who is
generally not an engineer or architect) will make his or her own
interpretation of the code. Who then will insure quality of
construction?

The answer, while obviously the Building Official, is also without
liability for making mistakes and there is no law governing the
unlicensed to prevent them from making mistakes that leads to poor
quality of construction or defects.

Without certification of those designing or building structural systems,
the code is nothing more than an unpopular book with few readers other
than those that are mandatory for those with licenses or titles.

Personally, I think we have made a royal mess of things and few are
willing to try and stop evolution in progress - there is too much at
stake and the public will be the losers.

The issues related to Simplified Static principles are not a local code
- it still must be a structure without irregularity. However, in my
area, most buildings are one story and can be modified as needed to
comply with regularity in design.

I think my point was more to the fact that we have stopped using our
intellect and have gone out on a limb seeking perfection over
practicality. Consider, for the moment, that home which was designed
using full-compliance (including rigid diaphragm analysis) in ten years
when it is sold and the new owners want to remove a few walls, add a
room, push out a window, or any of a thousand things that homeowners are
likely to plan when they purchase a new or existing home.

The difficulty in tracking the load path and recreating the lateral
resisting system of the building in order to re-balance or add (remove)
shear will be next to impossible. Certainly not as rational or easy  to
do as it is with flexible and tributary analysis.

While FEMA 268 and 302 state that a wood structure with a wood diaphragm
acts rigid, my response is who cares. Is there any real evidence that
the lack of additional restraint for those forces distributed through
the diaphragm have caused damage in homes? The answer is that we don't
know, have not done any more work in finding out and have published
nothing of consequences on the subject since Northridge. If you ask the
NAHB then the answer is absolutely not - homes did what they were
designed to do - protect the occupants and if they were damaged - so
what again? The owners of these homes were to blame because their
expectation of performance was unreasonable to begin with.

I don't buy this cr*p. However, I also don't buy creating a design
methodology that makes it impractical to change a home after it has been
constructed unless the original drawings and analysis are available to
understand the engineers intent.

I think this is the main reason why building officials are willing to
accept what an engineer has to offer as in the end, it should be left to
the discretion of the EOR.

So much for my own Diatribe!!!! >)

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: Monday, February 11, 2002 2:21 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: IBC 1617.6.2 & IBC 1617.6.3--1997 UBC 2320.2 & 1605.2 - how
to tell if your plan reviewer is really looking at the plans

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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