[TowerTalk] Guy Strain

Tue, 18 Jul 2000 11:07:24 -0600

On Tue, 18 Jul 2000 08:24:05 -0000 "c penna" <clive@gm3poi.prestel.co.uk>
writes:
> 
> Hi
> I wonder there is a formula for converting guy strain at a given guy 
> angle
> WRT ground to another angle. ie if a guy has a Max strain of say 
> 1000lbs @
> 60 deg angle WRT ground what would it be at 50 degrees?. I have 
> lowered the
> guy angle of my tower top guys and I'm interested to see what has 
> happened
> to the guy strain if anything. Can anyone confirm also that the 
> maximum
> strain in a guy should be 10% of the breaking strain or is that a 
> bit too
> conservative.
> 73 Clive GM3POI

I'm on vacation without my scientific calculator, and the only
calculating tool available on this mountaintop is a spreadsheet,
so here is a little table of guy angle (wrt to the tower) vs.
strain in the guy wire caused by horizontal wind. This is for the
case where wind is blowing in the plane of the guy wire in question.
You have to remember to add the pretension for the particular guy wire
being used to get the total tension.

Example:

For 1/4" EHS, what is the increased strain on the guy wire if the
guying angle is changed from 39 degrees (80% of tower height)
to 31 degrees (60% of tower height), if the horizontal windload
is 2000 pounds.

For 80% guying, tension = 3202 + 665(prestress) = 3867#

For 60% guying, tension = 3888 + 665(prestress) = 4553#

Caution! This mechanical engineering data is being provided by
an Electrical Engineer! Verify all data with a P.E. prior to
construction.

Dave Hachadorian, K6LL
Big Bear, CA
K6LL@juno.com

                                   additional
			                 guy tension(#)
guying			           (above prestress)
distance,		guy angle	     per 1000#
% of height		degrees	     horizontal
					     windload

100			45			1414
95			44			1452
90			42			1495
85			40			1544
80			39			1601
75			37			1667
70			35			1744
65			33			1835
60			31			1944
55			29			2075
50			27			2236
45			24			2437
40			22			2693
35			19			3027
30			17			3480
25			14			4123
20			11			5099
15			9			6741
10			6			10050
5			3			20025

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