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Re: IRC Braced Panels

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I do believe that used with an appropriate amount of engineering judgment as
to the applicability of the IRC a house can perform well in a high loading
event.  Much of the destruction observed due to the Northridge quake was
either poor construction or lack of engineering where engineering was
warranted within the prescriptive code.  I am not advocating IRC for all
houses.  It simply does not apply to all residential construction, but it
does have it's place.  You are right to make clear the distinction between
life safety and performance.  Confusing the two could result in lots of
trouble for sure.  However, I due think that the IRC can be used (again,
with sound engineering judgment) in high risk regions and the building would
perform well.  Many papers that came out of the CUREE project concluded that
much of the residential construction did well in the Northridge quake, but
there were obvious problems with a lot of residential construction due to
"operator" error, that is, misapplication of the prescriptive code.
Properly applied and constructed, prescriptive construction did well.

Ted Ryan

----- Original Message -----
From: "Dennis S. Wish, PE" <dennis.wish(--nospam--at)verizon.net>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, January 11, 2005 9:24 PM
Subject: Re: IRC Braced Panels


> Ted Ryan wrote:
>
> >Again, missing the point.  Regardless of whether the IRC calc's out or
not,
> >homes built in a manner consistent with the IRC generally perform well in
> >high seismic or wind events.  The IRC takes into account the redundancies
> >that we aren't able to in design.  The applicability of the IRC is fairly
> >restricted so that it isn't used in situations where an engineered design
is
> >warranted.
> >
> >Ted Ryan
> >
> >
> >
> Ted,
> This is where we have a fundamental difference of opinion. You're
> comment that "homes built in a manner consistent with the IRC generally
> perform well in
> high seismic or wind events" is not accurate. They satisfy the
> life-safety concerns of the code, but they do not perform well. The
> majority of homes that contributed to the $30-billion in damages to
> single family homes during the Northridge Earthquake were designed and
> constructed prescriptively (as were most of the homes in the San
> Fernando Valley).
> I am not arguing life safety - I am against the code from the position
> of performance - they simply do not do well in high risk areas. If you
> want to live in a prescriptively built home, you are welcome to, but I
> feel that the method of design should be disclosed to the buyer with an
> explanation as to the documented differences in performance during a
> moderate earthquake such as Northridge.. When you push the IRC be
> careful you don't  mislead the public by confusing life-safety and
> performance as they are two very separate issues and the homeowner is
> the one who is hit first in out-of-pocket deductibles. All of us are hit
> with the remainder when FEMA and other emergency management agencies
> come into play to provide low interest loans that the rest of the
> population must bear. It's not welfare, but our available assets could
> be better protected by improving the quality and performance of
> construction by restricting the IRC to low risk regions.
>
> Dennis S. Wish, PE
>
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