[TowerTalk] 130' 45G Gyued Tower Questions

[David Robbins]

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
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-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at 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, possibly 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 upward 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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