We talk about guyed towers and their minimal needs for big heavy bases vs.
free standing towers with enormous bases. I follow these arguments and
basically agree with the "standard" prescriptions but wonder about, as the
thread subject sort of indicates, the possible benefits of a hybrid design,
i.e. splitting the difference.
If the tower in question was designed to be free standing but was guyed at
the traditional lower guy level wouldn't we get the following:
1: a significant reduction in required size, weight, and cost of the
foundation/base as compared to traditional free standing,
2. a reduction in guy requirements compared to traditional guyed tower
arrangement (probably just one set of 3 guys) which retains the ability to
have a telescoping multi-section tower.
I haven't done a high resolution analytical assessment of cost but at first
blush it seems the three guys would be cheaper than the extra foundation
steel, concrete, bolts, base, etc. required if going traditional free
standing. Another issue to explore is how the addition of another set of
guys significantly lower than the traditional first set to supply resistance
to the base being levered sideways would be cost-wise compared to pouring
more base to handle the lateral loads. I'm just speculating (gut feel)
without running the numbers but I think the required addition to the base
size would be cheaper and certainly simpler and more desirable than the
three extra low mounted guys. My SWAG is that much of the base
traditionally poured for the free stander is to resist tilt, not lateral
movement of the base and little or no extra base may be required to
withstand lateral forces in the case of the hybrid tower with one set of
guys near the top of the first section of tower.
If desired, rather than a "pin" base a traditional hinged base could be used
to permit a retracted telescoping tower to be tilted over for "climbless"
maintenance.
OK guys, I have donned my Nomex long johns...
Patrick NJ5G
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