Bolt Shear Problem?
Bolt Shear Problem?
(OP)
A previous post (thread507-165823 - shear transfer at base plates) reminded me of something I've always wondered about.
Have you seen base plates, normally under signs and electricity/light poles, where the anchor rods protrude from the concrete and the base plate is held on the rods above and below with nuts? I've seen this detail on everything from the order menu at McDonald's, to 150' tall, 20 bolt, galvanized transmission line poles, to the large light poles in mall parking lots, all with gaping space under the base plates and between the anchor rods.
When I first noticed these, I dismissed it as a contractor neglecting to put the grout in. However, since they seem so prevalent, that theory is in doubt.
Does anyone know why this is done? Are those anchor rods really designed to take that axial load and shear over that unsupported length?
Have you seen base plates, normally under signs and electricity/light poles, where the anchor rods protrude from the concrete and the base plate is held on the rods above and below with nuts? I've seen this detail on everything from the order menu at McDonald's, to 150' tall, 20 bolt, galvanized transmission line poles, to the large light poles in mall parking lots, all with gaping space under the base plates and between the anchor rods.
When I first noticed these, I dismissed it as a contractor neglecting to put the grout in. However, since they seem so prevalent, that theory is in doubt.
Does anyone know why this is done? Are those anchor rods really designed to take that axial load and shear over that unsupported length?






RE: Bolt Shear Problem?
RE: Bolt Shear Problem?
RE: Bolt Shear Problem?
RE: Bolt Shear Problem?
The following link is to a design maunual for monopoles which discusses anchor bolt practices related to transission towers:
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This is part of the RISA site now which took over ERITowers software.
There's some interesting info and is a good page to browse.
http://www.risatech.com/risatower.asp
Regards,
-Mike
RE: Bolt Shear Problem?
Great Link!
RE: Bolt Shear Problem?
Thanks Mike!
RE: Bolt Shear Problem?
I have seen this used on transmission towers 5-6' in diameter, with 2.5" or larger bolts.