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Re: "Blown Away"

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1997 Uniform Building Code, Division III - Wind Design, Section 1615 -
General:

"Every building or structure and every portion thereof shall be designed and
constructed to resist the wind effects determined in accordance with the
requirements of this division."

Seems clear and succinct.  Probably the other codes say something similar.

__________________
John P. Riley, PE, SE
Riley Engineering
20 Oakwood Drive, Blue Grass, Iowa 52726
Tel & Fax:  319-381-3949
jpriley485(--nospam--at)peoplepc.com

> Recently, an architect client of mine and I were discussing a feature of a
> commercial building we were working on. He does lots of convenience
store/fast
> food combination facilities. One client has a "doghouse" at the front
entrance
> of the store, a "penthouse" type structure that allows a sign-logo above
the
> entrance that extends about eight feet or so above the parapet line.
>
> The doghouse itself is CFS supporting metal cladding, which sits on the
beams
> and joists of the main structure.
>
> The design drawings given me showed a CFS structure that was WAY
under-designed
> to resist code-specified wind forces, and I proceeded to design it
correctly,
> which made for a much "beefier" structure, particularly where the roof
members
> and overall connnections were concerned. When he saw this, he had a
negative
> reaction. "Too much", he said.
>
> I pointed out to him that we were building in an area where the design
wind
> speed is 120 mph (three-second gust). His response was "oh, that doesn't
matter,
> if they had a hurricane, the doghouse would just be blown off, and they
could
> build it back again".
>
> I had NEVER heard of this approach before! In essence, he's saying "just
design
> it to handle gravity loads and don't worry about wind, this is not an
occupied
> portion of the structure. If it gets scoured off, no big deal".
>
> Have any of you designed "components and cladding" type portions of a
structure
> under this approach? The architect insists it is perfectly valid: "we do
it all
> the time". Of course, this guy is the "Wal-Mart" of architects in our
market,
> and is used by developers here because he works cheaply, and doesn't get
in
> their way.
>
> I'm starting to rethink my relationship with him on this basis, but I'd
like to
> know if this is perhaps more commonplace than I realize, and if I'm
> "overreacting". I just can't imagine a building department anywhere
allowing a
> portion of a structure the possibility of being "blown away".
>
> Thanks