Anchor Bolt Clearance From Reinforcing

[Steve M]

New to Eng-Tips. Hope this is the right forum.

The client wants an 18" diameter light pole pier due to clearance with a gas line rather than the usual 24". This may work for overturning etc but the anchor bolts will need to be welded to the cage - no clearance. I wanted some feedback if this is per code; normal; etc since I have never seen a jurisdiction pier for street light poles 18" diameter, at least ones that have a cage.

 

[Lomarandil]

Do you actually mean that the anchor bolts need to be welded to the cage? If they're pre-installed, I'd imagine they could be tied to the cage bars, which would be more constructible anyway (or at least as-constructible -- might take a little finesse to get the anchor bolts in exactly the right locations).

Unless there's some odd electrolytic corrosion situation for other reasons on the project (since you mention the gas line), I don't see any reason to avoid this.

----
just call me Lo.

 

[JLNJ]

Usually the geometry of the base plate bolt circle is your limiting factor.

18" diameter drilled shaft - 3" cover each side - .5" ties each side - anchor rod diameter = approx. 10".

This equates to about a 7" square bolt pattern, max. Less if you are considering construction tolerances.

 

[Steve M]

Thanks guys. My main question was clearance between anchor bolts and cage if those are separate components. It looks like the ties or spiral can butt right against the ABs. In this particular scenario we have a 10" bolt circle with 1" bolts. with #3 ties we need a min dia of 17.75" so 18" will work. However with an additional (4) #5 verticals spaced evenly between the ABs we have a bit less than the .5% min vertical below the bottom of the ABs and the distance between verticals and ABs is ~3" which is certainly less than the CalTrans min of 5" (or 4" I saw elsewhere?).

So this is not an optimum solution - it won't work with the more normal bolt circles of 11"-12" - and shows why I don't see any 18" piers in JX specs for street light poles.