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