For relatively short towers (<100 ft?) with moderate loads
it appears that you can "get away with" putting the bottom
section in concrete based on the thousands of such
installations which are still standing.
IF you plan on side mounting a LOT of antennas on TALL towers,
a pier pin makes a lot of sense. It relieves any torsional pressures
due to misalignment of the tower and guy anchors and allows the
tower to rotate slightly when the antennas are torqued by high winds.
N4AR learned this hard way. He has two 200 ft Rohn 45 towers
side by side. The one that was loaded with 4 - 4L20's twisted,
shearing off the Rohn 45 legs where they entered his concrete base
when a tornado passed close by. Fortunately, the tower just rotated
on the concrete base.
de Tom N4KG
_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]
--
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
|