Yep, the lateral forces at the base of a tower are
quite small. The GUYS take the horizontal load,
transfering it to a vertical load on the tower. It is
my understanding that the limiting factor in tower
ratings is the vertical load on the bottom section.
That is why shorter towers, with fewer guy levels,
can carry larger antenna loads than towers at
their maximum height rating.
The primary purposes of a base are (1) to carry the
vertical load of the tower and transfered load from the
guy wires and (2) to prevent the tower from being
pushed up by freezing ground (make sure the bottom
of your base is BELOW your local freeze line).
de Tom N4KG
............................
On Mon, 13 Apr 1998 12:18:54 Pete Smith <n4zr@contesting.com> writes:
>At 01:28 AM 4/12/98 -0400, N3GPU wrote:
>
>>I wonder how many other 50-foot towers are holding up antennas
>without
>>benefit of concrete?
>>
>
>Well, I'll 'fess up to being involved with a club that had 30 feet of
>Rohn
>25 on top of a 9-story office building in downtown DC where the base
>of the
>tower was free-standing, held in place only by "guy wires" running to
>cast-iron vent pipes
>through the roof. Amazingly, it stayed up. Guess the moral is that
>the
>lateral forces at the bottom of a guyed tower are pretty minimal.
>
>73, Pete Smith N4ZR
>n4zr@contesting.com
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