A better approach might be to use a pier pin. Cut the existing base
flush with the concrete. Get a Rohn bottom plate made for a pier pin and
a pin. Then drill a hole in the center of the concrete and epoxy in the
pin. You're ready to go. See this link for an example:
https://www.dxengineering.com/search/part-type/tower-base-plates/product-line/rohn-pier-pin-tower-base-plates?autoview=SKU&sortby=Default&sortorder=Ascending
You'll probably have to replace the section you had embedded and cut but
this will give you a "by the book" tower base.
Les W2LK
On 7/4/2020 10:55 AM, Grant Saviers wrote:
I've made joiners and bottom plates for different tower sections for
Field Day, R25 to aluminum etc.
The Rohn leg bolts hold in shear so larger holes are not a good answer.
Getting two plates made with welded on pin and socket, that can be
shimmed to correct the angle makes sense as a solution, but needs a
lot of strength as you noted. I would go with the shimmed plates.
Have them galvanized.
For starting over, there are expanding grouts (Dexpan) that break up
concrete. Drill deep holes, mix and pour. Removing concrete with
rebar/tower section will be a PITA. A big excavator might pull it
straight out whole. I'd try that first. Or Dexpan to break off the
exterior then pull.
Grant KZ1W
On 7/4/2020 06:46, Blake Sobiloff via TowerTalk wrote:
Hi guys,
Due to the property lines and terrain I don’t have room to pour
another one next to the existing one, so jackhammering out the
current one may be the only option.
Some others have suggested drilling new bolt holes to make the first
section plumb. That seems like the easiest option, but I worry that
(depending on how close the new holes are to the existing holes) that
will weaken the tower right where the majority of the bending stress
is focused. I admit I’m naive about these things, though.
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