[TowerTalk] W-51 wind load

[Hank Lonberg]

Neil:

The WT-51 is the tower Tashijan sells  and the W-51 is the old
Triex design. First off the old Triex was designed using
"fastest mile" wind velocity and the old UBC. The newer WT-51
design conforms to the IBC or TIA/EIA 222 rev G using "3-sec"
gust velocity.  So 85 mph (3-sec) converts to 70 mph
(fastest-mile). In addition take a look at the alloy and size
specifications for the tower legs between the two. I believe,
but not sure, that the newer tower design uses a different leg
alloy and maybe even different diameter and wall thickness.

This is the most likely cause for the different specifications
coupled with a more analytically consistent design approach
with the newer codes (IBC and TIA/EIA).

Regards
Lonberg Design Group, Ltd.
H.S. Lonberg, P.E.,S.E. / KR7X
President


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Neil
Sent: Sunday, November 01, 2009 8:48 AM
To: towertalk at contesting.com
Subject: [TowerTalk] W-51 wind load

Good morning,

Can someone shed some light on why Tashijan tower's WT-51 is
rated for
13 sq. ft. of load for 3 second gust @ 85 mph, while my Triex
W-51 is 
only rated
for 9 sq. ft. of antenna load @ 50 mph?
The only difference that I can see, looking at the PE
drawings, is the  
Tashijan tower
required a bigger concrete base, which is the base I poured ,
3 x 3 x 
6'deep.
Very interested to hear what others feel is a safe loading of
this Tower.
Also, I want to re-cable the tower, I am thinking of going
from 3/16" to a
1/4" cable, does anyone in the Tri-state area (NH-VT-MA) have
a 1/4"
swaging tool I could use? I really hate to spend $300+ for a
tool I will
probably only use once or twice in my life......
Thanks....
73
Neil
AE1P
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 8.5.423 / Virus Database: 270.14.43/2474 - Release
Date: 11/01/09 07:38:00