[TowerTalk] Guying a self-supporter

[Bill]

Steve
First I did not claim to be an expert.  Quite the contrary.  I am only one who has doubts on the basis of my experiences.

At one time many years ago I had a free standing Universal tower made from aluminum.  It was not tapered in the manner you are suggeting.  Your analysis may well be correct for a tapered tower although I still have concerns about the buckling modes.  In the case of the Universal tower I would have substantial fears about its susceptibility to buckling depending on the spacing of the guys particularly considering the lower modulus of elasticity and yield strength of of aluminum.

The buckling mode is one where the deflection of the tower between the guys becomes excessive when the stresses of the resulting bending moments associated with the deflection are combined with the compressive stress of the weight of the tower and whatever it is supporting, the induced stress of the the guy loads, the torsional load of the twisting moments (which even if reduced by the guys through torsion brackets marginally increases the guy loads), the stress from the bending moments of the mast and antennas induced into the top of the tower and the bending moments from the wind load on the tower sections becomes so excessive that the principal compressive stress (Mohrs Circle) exceeds the compressive yield strength and casues the tower to buckle, usually between the guys.  In most commercial cases I would expect that the structural engineers have looked carefully at the peak stresses that are induced by all of therse loads and designed the distance between the guys to limit the column based horizontal deflection and thus the exposure to buckling.

But that is not what I understood the quesion to be here.  I understood it to be that any freestanding tower could be guyed and thereby make it less prone to failure.  That is were I disagree.  In the case of my Universal aluminum tower I would be very hesitant to do such a thing without having a design structural engineer clear it.

If my understanding was wrong then as Rosanna Rosannadana said, "Never mind!."

73
Bill
W7VP