> I am trying to figure out what tragic wind event triggered these
> ridiculous
> revisions! I am sure there must have been a bus load of innocent
> children
> involved, I just can't seem to find it.
Figure out how the original LRFD-only rules were developed and why
Appendices 13 and 24 of Section VIII Div 1 of the ASME Code are
linguistic nightmares and you'll probably find well-meaning members
who feel that greater 'accuracy' trumps ease of interpretation and
definitive language.
By way of a disclaimer, I confess I'm talking through my hat to a
degree, because I haven't done an actual wind load structural problem
in years. However I do have a pretty solid background in internal and
external fluid mechanics, and I know for a fact that figuring
aerodynamic loading on short prismatic shapes hasn't been rocket
science for a long time. Especially for low speed flows at ambient
conditions. It isn't terribly precise, but then neither is a lot of
engineering analysis, despite what you hear from FEA developers. And
it doesn't require CFD either, although test data and an
undergraduate fluid mechanics course help.
I'd be real curious if anyone on the list has actually gone through
the reasoning behind the new wind loading rules who would comment
what the changes represent and why the changes were necessary. I did
my own background checks on the ASME Code appendices I mentioned, and
tracked though the Code arithmetic and found I could provide the same
results in a far simpler form. It took me some time, but it's paid
off handsomely. I also did some background checking on the AISC
bolting design calculation. Turns out that those rules can likewise
be greatly simplified and in fact generalized while still following
the original principles. So can the rules for outstanding flanges.
The points made about balanced committee membership are taken, BTW,
but my experience is that even one 'expert' on a topic can pretty
much drive committee discussion in any direction he/she sees fit. If
in addition they feel that order effects are nice to account for,
second order effects are included even if the results only vanish
into the white noise.
Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw@skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania
1864)
http://www.skypoint.com/~chrisw/
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