To fully answer your questions requires a lengthy
analysis, and probably a LOT more detailed information,
which may explain the lack of response.
K7NV has written a new chapter for the ARRL which
I believe is or will be in the latest ARRL Antenna Handbook
on tower construction / mechanical design.
The strength of a cylindrical element is proportional to
the outside diameter to the 4th power minus the inside
diameter to the 4th power. This means that for a fixed
outside diameter, as material is added on the inside,
it has less and less benefit in terms of additional strength.
For example, a tube with inside diameter 3/4 the diameter
of the outside, will have ~70% of the strength of a SOLID
tube with approximately 50% of the weight.
de Tom N4KG
On Wed, 28 Feb 2001 "Wynand van Wyk" <zs6arf@telkomsa.net> writes:
> Hi there,
>
> I asked before but did not get a response ...
>
> I am busy erecting a 15 meter high ( 49 feet) commercial triangular
> steel
> tower sitting on a T-piece base that bolts into the concrete. The
> three
> legs of the tower slides into three tubes welded onto the T-piece.
>
> Can someone please explain to me how (1) the forces of gravity and
> (2) wind
> pushing against the tower will put stress on the legs and where the
> danger
> points could be. Will there be a difference between a guyed and
> unguyed
> tower, I would like to not use guys.
>
> In the process I have over engineered which is adding extra weight.
> I have
> heard that thicker steel is not necessarily going to calculate as
> more
> strength ... howcome ?
>
> 73
>
> Wynand van Wyk
>
> ZS6ARF@telkomsa.net
>
>
> --
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>
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