That is normal and as you expect it will bend back up as you add the other
guys. I don't see any need to force it up with cribbing, the rod won't take a
permanent bend from that small deflection. It might require a small adjustment
in tension when the rod bends back up from the other guys, but that should be
only a tiny effect.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Byron
Tatum
Sent: Thursday, April 04, 2019 14:25
To: Towertalk Reflector
Subject: [TowerTalk] 130' 45G Gyued Tower Questions
Hello- I have some questions regarding the effects seen on anchor rods when
installing first level of guys on a 130' 45G tower: The tower is
installed per Rohn 130 MPH specs, using same spacing, dimensions and angle of
anchor rod (38 deg). The anchor rod is made identical to the Rohn GAC5655TOP
being 10' long, 1.25" high strength rod, 1/2" 50 KSI plate at top end of rod
but with only 3 drilled 13/16" holes for turnbuckles, hole spacing same as Rohn
(5655 anchor has 5 turnbuckle holes) and concreted in a concrete anchor built
per Rohn AB3 dimensions. I have the tower free-standing at 41' right
now using a 5' concrete base section. A guy bracket was installed at 35' per
Rohn spec and I attached the guy/turnbuckle to bottom hole in anchor rod plate
and tensioned to around 600#. I am seeing the anchor rods bend downward to an
angle of around 30 deg as I increase the tension on guy wire. It appears the
rods have a very slight, just barely perceptible bow in them, po
ssibly from the wrenching action of the pull being from several inches below
the rod center (as plates are welded to rod and not pivoting). I
left the "slots" cut in ground (where anchor rod angles upward from top of
concrete to surface of ground) unfilled as I wanted to be able to observe the
effects on them and to install protective sheaths on them, where they exit the
ground, when tower is finished plus to backfill these with clean sand. The rods
were tarred and wrapped for corrosion protection. I backed the
turnbuckles off to a much less guy wire tension in order to reduce the downward
pressure on anchor rods and to allow me to install cribbing under the
turnbuckle plates to restore my anchor rod angle back to 38 deg. This
is the first tower that I have installed with fixed turnbuckle plates welded on
an anchor rod. It seems that all of the ones in past had the pivoting
turnbuckle plates and I did not notice these effects as the plates pivoted way u
pward with only bottom guy wire attached. So my questions are --1.
Has anyone else observed these things in installing a similar tower? Possibly
if I had backfilled the anchor rods these effects would not have been as easy
to detect.2. Would anyone have an opinion regarding using strong cribbing under
the turnbuckle plates in order to maintain original installed rod angle of 38
deg. as I restore tension to around 600# on bottom set of guy wires? I
imaging that when I get the second level of guys installed, of which turnbuckle
holes are centered on ends of anchor rods themselves, the rods will be pulled
upward, closer to the installed angle of 38 deg, and with installation of top
set of guys all will balance out for rod angle of 38 deg. My first
experience with fixed turnbuckle plates on anchor rods. Thanks for any comments
or advice.Byron W5FH _______________________________________________
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