[TowerTalk] Adding guys to self supporting towers

[Steve Maki]

On 8/13/2013 10:09 AM, Jim Lux wrote:

> On 8/13/13 6:47 AM, Jim Thomson wrote:
>> ##  The stress on the cross bracing is actually reduced when guys are
>> added to a
>> free standing tower, not an issue.

> How so?
>
> In a no wind static case, the guys add down force, some of which will
> appear on the diagonal cross braces.  How much depends on the relative
> compression stiffness of the brace vs the verticals.
>
> In the wind loaded case, the guys transform some of the horizontal
> bending load into down force.  That could be a wash in terms of loads
> but it's hard to tell, depending again on the relative stiffnesses. E.g.
> downwind side has less load due to bending, but more load due to guy
> induced downforce, but the guy downforce is distributed among all
> three/four vertical legs.

I'm having a hard time with this. It seems to me that in the guyed 
no-wind state, the added force to diagonals from guy tension will be 
almost nonexistent as long as the guys are tensioned equally. Isn't all 
of the additional vertical force, well, vertical?

I thought that stress in the diagonals is the result of flexing of the 
legs, which MUST be most pronounced in the unguyed windy condition???

-Steve K8LX