[Antennas] Fasteners
[email protected]
[email protected]
2002年6月26日 16:21:56 EDT
Id feel undressed without the bolts. Wind loads are complex and dynamic.
Vibrations, creep, and other concerns enter this non structural mind. It pays
to be cautious when designing a tower for the long haul.
ie My 56 ft Heights aluminum tower was purchased 25 yrs ago to support
about 10 sq ft of antenna/mast wind loading. It was preengineered to be
freestanding in 100 mph winds ( conservative-my choice). I then GUYED it at
the top for additional security.
When I took it apart ( twice in 25 yrs) the sections were tough to separate
but I could finally separate all but two 8 ft sections. After the second
dismantling I noticed this regarding the bolts and bolt holes for each
section:
- most bolts were worn away by about 30% of their diameter.
- most bolt holes in the aluminum had enlarged by about 1/8th of an inch.
- As well, I would guess that bolts also reduce the likelihood of
sections being forced too tightly together over time.
Clearly there are almost infinite dynamics going on under wind load
conditions. I gotta think the bolts were adding to tower strength and
extending its lifetime, by damping out vibrations and reducing internal wear
and tear.
I too would love to hear what tower manufacturs have to say about tower life
and wear and tear issues on steel and aluminum towers over extended periods
of time..ie 10-20-30-40 years.
Considering the weight and my personal experience, I wouldnt hesitate to go
with an aluminum tower again should the need arise.
Bob