bolt shear problem

huangyhg

bolt shear problem?
a previous post (
nuts and washers under the base plate could be for leveling purposes, ie keeping the pole on a vertical axis.
i agree withyou, i've looked nerviously at those base plates on highway lights, mounted on top of the new concrete barriers.  i haven't looked too closly (being more preoccupied with avoiding the other idiots on the road rubbering necking about) but i don't think there's a shear spigot in the middle of the joint.  so i think you are left with a dozen bolts holding onto the 100' light post "in quite desperation".
this non grouted base is standard in the the electric transmission industry and in electrical sub-station for support of bus, components and switches.  the anchor rods are designed to take the combined shear and tension from the enormous moments generated by wind and seismic. these are vertical beams and not axially loaded columns as in buildings.
swearingen,
the following link is to a design maunual for monopoles which discusses anchor bolt practices related to transission towers:
star for you mike.
great link!
i guess that answers the question - yes they are designed, and the reasons for this design appear to be internal corrosion and the ability to adjust plumbness.
thanks mike!
if you have a heavy object with moment, it makes sense to support the object on the foundation, with bolts to hold it down.  but where the weight of the object itself is minimal, then the uplift on one side of the bolt pattern is pretty much the same as the compression on the other side.  so long as you don't get local bending of the bolt, it should work fine.
i have seen this used on transmission towers 5-6' in diameter, with 2.5" or larger bolts.