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Re: questions!

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One problem with the ASCE 7 is that the research behind it has almost entirely
been funded by the Metal Buildings industry, and thus reflects a definite slant
in their direction as far as the recommended criteria. Why is it that other
"building industry" interests have not made themselves part of ASCE 7

Because "good enough" is typically "good enough" for most engineers (witness the
hubbub that begins when I utter those four little letters "LRFD"). Most
engineers simply want an equivalent pressure, and let it go at that (witness the
still simple-minded procedure for wind load computations in UBC 94).

But the metal buildings folks try to engineer down to the gnat's arse. They want
every ounce of steel out of their designs they can get, and so they want to know
the difference between the equivalent pressures at "discontinuities" like
corners and eaves, and that at the center of the structure.

Look at the "examples" shown in your ASCE 7, and also the companion "Guide to
Use of the Wind Load Provisions" authored by Kishor Mehta. It's ALL metal
buildings. They're not even very clear about how to handle a flat roof with a
parapet all around (Does the parapet provide some shielding for uplift on the
roof? Do you apply a "windward" load on one side and a "leeward" on the other
side of the same parapet? It isn't at all clear!)

They weenie out of it all by recommending you do a "wind load test" for
structures that don't readily lend themselves to the ASCE 7 recommendations--all
very well for BL wind tunnel facilities like that at Texas Tech, but highly
improbable for use by designers of most low- and mid-rise buildings that
represent the preponderance of such facilities for commercial use.

Much as I love the advances in the provisions of ASCE 7 over the years since it
was established, I am wholly unsatisfied that only one industry, metal
buildings, has chosen to get involved in that development.

Thanks. Getting off soap-box now, and turning it back over to you "shake, rattle
and roll" guys in Seismic Zone 4.

Keith Fix wrote:
> I want to know whether large numbers of re-entrant corners in relatively small
> buildings (1-4 stories, 250 ft maximum width) are correctly modeled by building
> code prescribed wind loads.  Thesis: "ASCE 7-98 Wind Forces are (in)appropriate
> for the design of mid-sized buildings with numerous re-entrant corners".

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