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How to overcome the moment at the base of a footing of a lamp post

How to overcome the moment at the base of a footing of a lamp post

How to overcome the moment at the base of a footing of a lamp post

(OP)
It is stadium lamp post and the moment at the foundation level is about 5000kNm. So how to overcome the uplift force generated? Also there are anchor bolts in 20 numbers in a circular arrangement for a depth of 3000mm.

RE: How to overcome the moment at the base of a footing of a lamp post

Either an augercast concrete pile or a large concrete spread footing.  

Mike McCann
MMC Engineering

RE: How to overcome the moment at the base of a footing of a lamp post

I don't think a single pile is going to do it.  A spread footing will work if the soil conditions are adequate.  If not, a group of compression/tension piles, either precast or bored piers, with a big pile cap, would be required.

RE: How to overcome the moment at the base of a footing of a lamp post

Maybe not a solid pile but a concrete cyclinder gets used for wind farms. If you have rock, maybe rock anchors with hokie's solution of a pile cap/footing.

3000mm seems deep for the bolts, I would suggest the bolts be bolted to a ring plate at the bottom to reduce this requirement for depth.   

Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that them like it

RE: How to overcome the moment at the base of a footing of a lamp post

I have done stadium light poles before, as well as some highway high mast lighting.  They have all been done with a single large diameter drilled pier.  The diameter can get quite large, 5 to 6 feet in diameter is not uncommon.  The depth is governed by the soil conditions, and the diameter of the pier.

RE: How to overcome the moment at the base of a footing of a lamp post

Just out of curiosity, can you describe the pole and light fixture a bit.  That is a very high moment (if my conversion to imperial is correct).  That is much higher than I have seen from stadium poles that I have done.  Mine have been in the range of 100 ft high, with fixtures that have 75 SF tributary area at the top.   

RE: How to overcome the moment at the base of a footing of a lamp post

(OP)
This is a light post that is used in day and night cricket matches. Height is about 45m.

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