1. How does one tension a guy cable if there is insufficient travel
in the turnbuckle?
I have a long-link chain to which I can attach the turnbuckle, so
it's merely a matter of putting the shackle through a different
link. However, I will have to keep something like 1 kN (or 225
lbs, if you really must) of tension in the cable while moving
the shackle.
2. A second, albeit more subtle, question: I have pretensioning
specifications for 8 mm (rougly .4") cable. However, I'm using
insulators with dead-ends, adding rougly 1 kg to the cable every
4,5 m (or 2 lbs every 15'). My logic says that the larger
distributed mass will cause more sag in the lines. If the same
amount of motion is to be allowed, more pre-tension will have to
be used. Is this correct? If so, how can I estimate the
required amount of pre-tension?
To put some figures to it: The upper guys are at the 33 m (109')
level. The manufacturer specifies a maximum of 65mm (2.6") of
motion at the top. The maximum wind load with the full antenna
complement will cause 10 kN (2250 lbs) of tension in the cable.
Recommended pre-tension is 1 kN (225 lbs).
Chris R. Burger
ZS6EZ
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|