[TowerTalk] Windload calculation and freestanding versus guyed

[Trond Thorman]

Gentlemen,
Many of you are very experienced in tower design, erection and use in
various conditions and I'm appealing for your input.

I'm curious on how to calculate the windload of an aluminium tower design.

I'm contemplating a purchase of a 12m (40') + top tube of 3m (9') lattice
tower and although I can get hold of manufacturers guy calculations, however
I cannot access any information to the tower free-stand capabilities. The
manufacturer states that it has been well tested as a free-standing tower in
harsh climates but does not want to commit himself to any data related to
free-standing deployment. He recommends guying above 9m (30').

The statement puzzles me and asked him what actually brakes or what is the
weakest point of a free-standing mast. His answer was the junction between
the bottom of the mast and the foot. So I guess here's my questions:

- How do I calculate the wind resistance of a free-standing tower, knowing
all the mechanical dimensions? (no aerials)
- What decided the strength of a mast bottom section and its connection to
the foot?
- How do I calculate the foot dimensions (amount of concrete) for
free-standing use?

Are there any good books available on the subjects? How does tower
manufacturer attack and solve the problem? I'm extremely keen to go find out
and to get to the bottom of my curiosity.

Best Regards and 73 from a very pleasant and mild London (UK)
Trond (G0TRD/SM7DJX)






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