Are there any engineers out there?
Heres what I plan to do:
- Mount my 60' rohn 25g on top of my 15' high office building
- The roof top is concrete with asphalt. I'm assuming its 4" thick.
- The base plate and guy points all fall on 2' square concrete pillars
that support the roof. The guy points are going to be located to meet
rohn specs as far as distance from the tower and 120d spacing.
Now for my question to the engineers listening.
My guy plates will be 4" to 6" square and will be mounted to the concrete
with expansion bolts. The specs on the bolts say a 3/8" diameter bolt
embedded in 4000 psi concrete and 1 1/2" has a pullout of 3219lbs. If
I use 4 of these per plate thats a total of +-12,800 lbs. If that
calculation is correct my 2 sets of guys will fail first since they
are rated at 4000lbs each or a total of 8000lbs.
Now thats my approach to it. Am I missing something here or am I on
the right track? By the way the name brand of the bolts are Hilti. I
know that they also offer an epoxy method but really don't want
to mess with them.
I'm going to use the same method on my 2' square baseplate. The shear
rating on the above bolt is 4000 lbs and using 4 of them is a total of
16000lbs. So I don't think I'll have a problem here.
Any advice will be greatly appreciated.
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