[TowerTalk] Bottom Section In Concrete and Bolt question

[K7LXC at aol.com]

In a message dated 7/5/2007 12:36:57 P.M. Pacific Daylight Time,  
towertalk-request at contesting.com writes:

>  I have a 60 foot Jontz tower in good condition.  I plan  to put the first 5
feet into the hole with gravel at the bottom so it will  drain.

>  1.  Do I need a rebar cage in the concrete  around the portion of the tower
set in concrete?


    Yes, and it needs to be designed by an engineer.  It's function is to 
hold the concrete together while it's curing to prevent  cracks in the base. You 
can make some educated inferences from similar towers.  Try the Rohn online 
catalog or the Trylon site. All tower structures have the  same forces going on 
and use similar designs and if in doubt, over-engineer  it. 
 
    Are you going to get a building permit? If so,  you'll probably need a 
stamped PE package to be submitted with your  application. If not, you might 
want to find a PE to design the base and rebar  cage anyway. There's probably one 
or two in your local ham club.  

>  2.  When taking the tower down I broke many of the  bolts holding it
together.  They are unique and unavailable.   What grade/type of bolts do I
want to use to replace them?
 
    Check with the manufacturer. Lacking that, what  grade was used that you 
broke? Check the number of hash marks on the bolt head  and that'll tell you. 
And again, if in doubt - get a stronger grade. The cost  is insignificant. In 
commercial installations, nuts and bolts are not re-used  anyway. 

Cheers & GL, 
Steve     K7LXC



 



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