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RE: IBC 2007 Wind calcs.

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Last year, ASCE/SEI ran Trial Design Problem 01-06 that included
submissions of wind and seismic forces for a simple box building.  These
trial design problems are intended to test application of code
provisions by practicing engineers.  (It includes some discussion of
application of the 10 psf minimum wind pressure.)  A "White Paper"
summarizing the trial design results can be found at:
http://content.seinstitute.org/committees/business.html

As with past trial problems, there were significant variations in the 54
solutions submitted by practicing engineers.  Some engineers chose the
simplified wind provisions from ASCE 7-05 and some chose to use the
analytical procedure.  The White Paper notes that results were much more
consistent among those that used the simplified procedure; but "The
Analytical Method (Method 2) is not clearly understood or consistency
applied as demonstrated by the large variation in the design wind
pressure."  

Personally, I find the analytical wind provisions "too complex" with
respect to the time and effort needed to apply them vs the benefits
derived.  But the trial design problem identifies another significant
problem with the complexity - it actually increases the incidence of
errors in applying the code provisions. 

Another conclusion that can be reached from the trial design problem is
that an engineer's calculation for development of building loads from
code provisions should be checked by another qualified engineer.  It is
likely that an independent set of eyes and a different viewpoint in code
interpretation would reduce the incidence of errors in derived design
loads. 

Bill Sherman
CH2M HILL / DEN 
720-286-2792 

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)umich.edu] 
Sent: Thursday, February 14, 2008 5:23 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: IBC 2007 Wind calcs.

There is a BIG difference between being "not as easy as the UBC" and
being complex enough that it is tough to use.  I think that both Chris'
and my point is that we don't disagree that it is more complex than the
UBC, but it is also not hard to use (in our opinion).

Personally, I don't know how much of the grumbling is due to 1) people
not liking change; 2) people just not being used to it and have to
adjust to it; or 3) people just not understanding it because it is too
"complex" for them.
I suspect that a lot of it is #1 and #2 and that once people get past
those two issues (which time will solve), that #3 is really a non-issue.

Regards,

Scott
Adrian, MI

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