[Antennas] Fasteners

[W3HKK@aol.com]

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