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[TowerTalk] Unguyed SCANDO elevator mast "tower"?

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Subject: [TowerTalk] Unguyed SCANDO elevator mast "tower"?
From: "tom scott " <>
Date: Wed, 5 Apr 2006 13:26:51 -0700
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I have purchased a tower that I will soon be moving and wanted to get some 
opinions about using it unguyed. 

This is actually a construction elevator "mast" made by a company named "Alimak 
- Scando-I." This thing is amazingly strong, roughly 2' square, 3" steel pipes 
with welded "H" cross members of 3" angle iron, and "Z" cross members of one 
inch tubing. One five foot section is well over 200 pounds. It is rated to 
support 25 workmen and about two and a half tons of elevator car and ballast 
weight (vertical load). It is rated for these loads when tied to an adjoinging 
structure every 25 to 30 feet, but the top section can be free-standing up to 
25 to 40 feet above the last support. It is currently set into a large chunk of 
concrete and free-standing to a height of almost 90 feet and has been there for 
a number of years. Each mast section ties to the next with four 1" UNC bolts 
(forgot to notice what grade), and insert bushings to splice the 3" vertical 
tubes. There are six threaded bushings (5/8" UNC)intended for mounting a gear 
rack welded to each section, three on each of two sid
 es, which will be handy for mounting antennas and cable anchors. 

I want to use it on a mountain top where it will see much higher winds than it 
currently does, but we are only planning to put a variety of low wind-load 
VHF/UHF antennas for repeaters, nothing like an HF beam. I have a book of the 
manufacturer's data for the tower, but there is no data for using the mast 
sections as lightly loaded free-standing towers. Just specs like those I have 
given related to the "system" application as an elevator.

I have some better pictures if anyone is interested in seeing them.

If this thing will support four or five tons at 25' in the air freestanding, 
should I be at all worried about a few hundred pounds of antennas at 85' in the 
air? The problem of course is that the loads it is designed for are primarily 
vertical crush loads, but still this thing is VERY beefy. The only thing that 
worries me a little is wind-induced harmonic motion gettting its own mass 
moving against it. I can go get it engineered, but I don't have any 
manufacturer's specs for the mast sections alone, or for this application. I do 
have a very cooperative rural building department that will not be a problem. I 
am just concerned with not losing the tower and antennas (not to mention 
whatever they might fall on). I have thought about running some very steep guys 
up about half way just to dampen the sway in a wind. 

Interested in thoughts from any tower experts out there. 

Tom - KD7DMH

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