jimlux wrote:
>> <snip>
>>> Putting guys on will inevitably increase the compression loads on
>>> the downwind side a bit (from the vertical component of the
>>> tension in the guy, even if slack when unloaded, they will
>>> develop tension under wind load).
>> BTW, could you clarify that comment a little? I think the peak leg
>> compression (which occurs during strong wind in either the guyed
>> or unguyed state) is lower when guyed (reasonably), and you
>> yourself worked that out with an example a couple years ago, and
>> which seems obvious to me.
> the guy has some non zero tension, which has to resolve into a
> horizontal component (resisting the wind force) and a vertical
> component (pushing down on the leg). The wind force also bends the
> tower in the downwind direction, creating a compression load. And
> gravity. However, the bending load will be reduced by the horizontal
> force from the guy. So you can probably figure out an arrangement
> which either improves or worsens things.
So it's not inevitable then.
>
> If you throw in the wind loads on the tower itself, and the
> possibility of multiple guy levels, it gets pretty complex.
Complex yes, but the more guys (up to a point) the better I think.
On guyed towers, you see a pattern develop after seeing a lot of them.
This is really simplified but: 12" towers like to be guyed every 30'
with 3/16" wire, 18" towers every 40' with 1/4"-5/16", 36" towers every
60-80' with 3/8"-1/2", etc.
I think this gives us clues about what would be appropriate guying on a
self supporter. The upper bays would be closer spaced and use smaller
wire. If you keep the tower relatively vertical, straight, and untwisted
during winds, then it will survive.
Steve K8LX
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