K3BU wrote:
>> Depending on the angle
>> of the guys, these forces can be huge, often exceeding the vertical
>strength
>> of the tower. On the other hand, towers intended for guying are designed
>for
>> high vertical and very low lateral/bending loads.
>That is nonsense!
>If the guy wires can hold the load, the tower will be stressed less than if
>self-supporting. When you have self supporting tower, one side gets stressed
>on "pull" while the other side is stressed on "push," the angles are steep
>(legs) the forces are large. If you put the guy wire you are freeing the legs
>from "pull" and they share the load on "push" which is shared and less. Self
>supporting towers are usually heavier material and stronger than guyed
>towers. No way you can exceed vertical strength of the tower. Guy wires on
>such tower do not need to be tightened, some slack might be beneficial,
>allowing tower to do its job, and in case of excessive forces and bending,
>the guy wire will help. It is helpful to have the guy wire hanging down
>normally and in case of severe ice and wind load, hook it up to the anchor on
>the windy side.
That makes sense to me - I've often wondered about claims that guy
wires will over stress a self supporter, especially without even
mentioning guy angles.
In order for a self supporter to be a self supporter, the legs have
to be HEAVIER than for a guyed tower of the same height, because
the wind force transmits into a compressive load on just one leg
(when it hits perpindicular to a face). I think the math would show
that a 45? up wind guy adjusted to equalize the compression on all
three legs will improve the tower rating in all cases.
I'd like to see that worked out by someome who knows what they're
doing.
73,
Steve K8LX
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