To the list:
The IBC, both 2000 and 2003, and the UBC all refer to the TIA/EIA-222-F
specification when they discuss the wind load and analysis of towers. The
actual design criteria for towers can be considered the same for all three
codes. Actually the IBC 2003 is the latest version of the IBC 2000. The only
variables that change from location to location for all the codes is the design
wind velocity and the site soils.
The TIA/EIA design wind velocities as well as the UBC's are based on the
"fastest mile" wind speed; while the IBC (2000 & 2003) as well as the ASCE 7-02
are based on the "fastest 3-second" gust. In the IBC's there is a table that
relates the two wind velocity concepts, fastest mile vs 3-second gust, together.
The site soils in all the codes are handled by 5 basic types with extremely
conservative allowable strength values.
So in essence there is only 1-design standard and it doesn't matter which code,
UBC or IBC. The real focus is to educate the building offical that this is the
case. A licensed structural engineer in the particular jurisdiction has more
credibility in this regard than either the permit applicant or the manufacturer.
In a general comment to all on the list regarding the discussion of the cost of
engineering.
I feel that it is demeaning to the profession and to me personally. What you
are actually paying for is the accumulated knowledge and understanding of all
the physics involved in the wind or seismic design of the tower as a structural
system.
If you don't like the fee, my suggestion is to spend 4+ years in accreditied
university coursework with passing marks; take the 8-hr EIT test and pass;
spend 4 years under the guidance of an licensed engineer(s); take the 16-hr
structural licensing examination and pass, in the state of your choice and
then "DO IT YOURSELF".
Regards
Lonberg Design Group, Ltd.
Hank Lonberg, P.E.,S.E. / KR7X
President
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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