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Re: Concrete Poles

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Don't make this out to be more than it is. Probably every roadway lighting
pole, traffic signal pole, sports lighting pole you see around you has a
foundation designed with the pole embedment equation found in the UBC. You
can design either a round or square footing for a constrained or
non-constrained condition. If the pole has a base plate, set anchor bolts in
the foundation. If it hasn't a base plate, embed it in the foundation as your
contactor suggested giving some thought to foundation reinforcement around
the pole shaft.. You will find that the base forces are not that high for
this type of structure. Divide your base moment by the shear to get the "h"
value for use in the equation. Your base shear will be the "P" force in the
equation.  If you haven't a soils report, use worst case soil conditions in
the UBC. Speak with local contractors to see what drill rig diameters are
available before designing a round caisson type footing and don't forget to
design the footing itself for bending with maximum moment occuring about 1/3
the embedment depth.


Michael D Zaitz wrote:

> Hello,
> A cleint has a concrete pole that is 35 feet above ground.  The pole will
> support some speakers to be used for an emergency broadcast system and
> will be designed for 110 mph winds.  We have the option of using a spread
> footing or encasing the pole in a caisson.  What is typically done for
> lightpoles that you see by the highway?  The electrical contractor
> recommended that we drill a 5 or 6 feet deep hole, stick the pole in it
> and fill it with concrete.  Any comments?
> Mike Zaitz