In a message dated 96-08-03 22:34:21 EDT, you write:
>My first question concerns the tower base. I have the concrete base plate
>(I think the number is BPC-55). It is designed to sit on top of a concrete
>base with a pier pin dropped through its center into the base. If I drill
>two additional holes of about ¾" and drop additional anchor bolts through
>the plate and down into the concrete. Do you feel this is adequate support
>at the base? I am primarily concerned about the torque applied to the base
>when tower rotation starts and stops. If this is a workable system, I?d
>prefer to go with it rather that put a section into concrete.
Hi, Ralph --
Sounds like a great project! My initial response to almost any inquiry
is to "do what the manufacturer says". If you use the pier pin section, then
you should use it as Rohn has designed and intended. While you have to
temporarily guy the first couple of sections until you get to the first set
of real guys (more time and hassle during the installation), using a pier pin
is designed for bigger tower loads. It insures that the compressive loads
are brought down to a single point rather than possibly having unequal loads
on the tower legs. The pier pin equalizes the leg loads as well as allowing
the torque forces to harmlessly dissipate. So it is in you interest to NOT
pin it if you use it. On the other hand, putting a straight section in the
concrete is another way of doing it. Not only is it much easier and faster
during the installation IMO (no temporary guying), if the base and the
sections are plumb then the leg forces are within the manufacturers specs and
do not present any particular problem. BTW, you are in Stearns county which
is an 80 MPH zone - that's your design criteria. Also, do you have the Rohn
book?
>
>My second question is the minimum distance between guys you?d be comfortable
>with. My feeling is 50 ft. is about max.
What does the manufacturer recommend? See remarks above. For a 190 foot
tower, Rohn specifies 5 sets of guys with 37 foot spacing. Do you have the
Rohn book?
>Finally --- I wish you were closer so I could hire you to do this project
>for me. My available free time is too little for the demands of the
>project, and its tough to find someone who is both savvy about amateur needs
>and able to do good tower work.
Actually, Ralph, have safety belt - will travel. I am expanding my
tower services and would entertain helping you with your project. My rate is
$60.00 with $75.00 per day out of town per diem. For your project, renting
an electric windlass is the only way to go. I could function as the project
manager to get the project completed safely and quickly. A project like this
will take about 5 days. You would provide the additional labor required. My
travel cost would be equivalent to the cost of an airline ticket. Since I
have and need a bunch of rigging gear, actually flying may not be practical
but the travel cost would be comparable. Let me know.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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