[TowerTalk] Calculations

[Hank Lonberg]

Alan:

I find this interesting to say the least. The IBC never references the UBC
it does reference the ASCE 7. In IBC 1609.1.1 which states that the wind
loads are to be determined in accordance with section 6 of ASCE-7 but gives
the following exception, among many

1609.1.1.5 - Designs using TIA/EIA-222 for antenna supporting structures and
antennas.

UBC Section 1604.1.2 acknowledges TIA/EIA-222 as a recognized national
standard.

UBC Section 1618 Defines the basic design wind speed as the 50 year fastest
mile wind and refers to a wind speed map and tables 16-F;16-G and 16-H.

Further more the IBC in section 3108.4 specifies the TIA/EIA-222 as the
standard for determining wind loads for television and radio towers.

Go figure.

There is a commentary section for the 97 UBC that acknowledges that the UBC
wind load procedure for triangular latticed towers (our kind) is
conservative and suggests using another recognized national standard.

My contention in my message to you is that if the wind loads are determined
by the TIA/EIA specification which is very similar to the procedure in ASCE
7, and these loads are used to design the foundations for the structure in
accordance with the UBC or IBC then the structural system is adequate and
meets the minimum life safety requirements of the cited code, UBC or IBC.

By the way my comment on fee was directed at any specific individual.

Regards

Lonberg Design Group, Ltd

Hank Lonberg, P.E.,S.E. / KR7X
President

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Alan C. Zack
Sent: Tuesday, September 14, 2004 3:58 PM
To: Richard (Rick) Karlquist (N6RK)
Cc: towertalk at contesting.com; WarrenWolff at aol.com; Jim Lux
Subject: Re: [TowerTalk] Calculations

My accepted wind calcs reference IBC 2000 Wind load UBC Sec 1618 and 
UBC Tables 16.  I am not sure but my Bldg Inspector seemed to think 
this was the same requirements as shown in UBC-97 but just contained 
in a different section of IBC-2000.  IBC-2000 has a special section 
regarding towers.  I don't know this for sure .

Richard (Rick) Karlquist (N6RK) wrote:

  > A possible reason would be that IBC-2000 might be a stricter spec,
> and the tower is not engineered to meet that spec, at least with
> a usable antenna area on top.  Does anyone know if IBC-2000 is a
> tighter spec, or just a different calculation algorithm?
> 
> Rick N6RK

-- 
__________________________________________________________________________ 

Alan Zack
Amateur Radio Station K7ACZ
Las Vegas, Nevada, USA
Quality Engineer, The Boeing Company, Retired
Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
U.S. Coast Guard, Always Ready, Always There
Every hour, Every day, Around the Clock and Around the World
SEMPER PARATUS
http://gocoastguard.com


_______________________________________________

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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