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Re: IRC Braced Panels

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Dennis:

I will offer a comment...keep in mind that the IBC (and UBC, BOCA, SBC,
NFPA 5000) are just as much a "life-saftey" code as the IRC.  Currently,
all model buidling codes that are used in the US are basically designed to
be a minimum life-safety code.  While there are some "performance
enhancering" provisions in some of the modern codes that are aimed at
reducing damage costs, the purpose of "just" designing to code is to
protect life not property.

Now, it is certainly likely that a lot of the provisions in the IBC (and
the other "engineered" codes) will make the performance of structures even
exceed a minimal life safety level and thus result in homes built per
"engineered designs" sustain less damage in seismic or severe wind events
and thus result in less cost to homeowners, but that is NOT the driving
intent behind IBC provisions.  Like the IRC, the IBC is a life safety
code.

So, if you complaint with the IRC is that it is only a life safety code,
then you really have the same complaint with ALL codes in the US.

Now, I would certainly agree that the IRC is abused and many times used in
situations where an engineered design is warranted.  This will mean that
you might have more "IRC" (or conventional built homes) homes that sustain
significant damage resulting in more cost after an event.  But, this could
be more a function of improper use of the IRC rather than it being a "bad
code".  And even then your post that talked about the excessive cost of
the Northridge earthquake, especially prescriptively built homes, still
points out that the goal of the IRC/prescriptive built home (and
engineered homes per IBC/UBC/etc) was largely achieve...there was little
to no loss of life.

I applaud your desire to have some sort of disclosure to home owners that
their house was designed per "presciptive methods" (i.e. IRC or
conventional framing in the UBC), but do you honestly think that it would
really change anything?  Considering how many current homeowners "squawk"
at paying for any engineering, do you honest think that just telling some
potential homeowner that their house is going to be designed/built per an
"inferior" method that COULD (maybe) cost them more down the road will
cause many to want to pay for an engineered design upfront?  If so, can I
live in your fantasy world?  <grin>  Most people want the minimum cost
upfront and don't worry that they could, maybe, end up paying more in the
long run.  The vast majority of people in this country are not
"programmed"/taught to think long term...they are ingrained in "what is
the short term bottom line".  In the end, most homeowners would rather
spend the extra couple thousands of dollars on nice kitchen cabinets or
nice interior finishes than on some engineering that could result in their
house potentially performing better and lasting longer.

Regards,

Scott
Adrian, MI


On Tue, 11 Jan 2005, Dennis S. Wish, PE wrote:

> 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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