Phillystran stretches LESS than EHS, at least that's the way I understand
things. My tower has 18 guys composed mostly of Phillystran with EHS at
each end near the tower and ground posts, and I see no problems maintaining
tension, although it has been up for only about 6 months. IMHO, if the
elements are in series and both within their proper ratings for tension,
the "strechiness" won't matter in terms of breakage, but if one element
really stretches a lot so that proper tensioning is lost, you could have
sway, fatigue, torsion and all sorts of other problems. BTW, I am not only
not a ME/PE, I am a EE/software guy, the most dangerous kind of tower
person there is!
73 John N5CQ
-----Original Message-----
From: Bill Aycock [SMTP:baycock@hiwaay.net]
Sent: Monday, August 31, 1998 8:08 AM
To: Tower Talk
Subject: [TowerTalk] mixing EHS and Phillystran
I have a serious question for the professionals out there. (I am not a PE,
nor do I have lots of Galvanized in the air, but I am an Engineer)
The question, or doubt, really, is in the effectiveness of mixing
Phillystran with EHS. It is not a question of strength, but of the
difference in the stretch properties of the two. I do not have the
figures, but I remember some comments from earlier postings that indicate
that the Phillystran, at comperable strength, has much more stretch than
EHS.
The effect of this will be to make the Phillystran almost ineffective when
under added load with the EHS, where a similar set-up with Phillystran
alone would be great.
If you want to make a simple experiment, parallel a string and a strong
rubber band- as you pull the pair, the load is almost all taken by the
string, until it breaks.
Bill
Bill Aycock W4BSG
Jackson County, AL
EM64vr
W4BSG is "vanity" this time, but was
earned by exam in 1954, the first time.
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