high mast lighting / sq footing / cut rebar

[boffintech]

Am doing the special inspection work on new high school football stadium. The high mast lighting was originally to be placed in deep augured holes but due to encountering rock several were redesigned and are to placed on spread footings.

The footings have # 5 @ 18" EW top and depending on the size of footings a specified number #6 EW bottom. The drawing appears to show the pre-cast concrete mast standing vertically through both mats of rebar. So the contractor simply cuts a round hole through both mats of rebar so that the mast can rest on the bearing elevation of the footing.

OK, not much weight, but depending on the number of lights lots of moment. But the # 6 bottom mat has a hole cut in it? Does that sound right?

Just want a heads-up before I ask the EOR.

 

[kslee1000]

If I understand correctly, the precast pole is to be embedded in the spread footing prior to concrete placement. If this is the case, it is correct to cut hole on the top steel mat, but I would set the pole at a distance above the bottom mat to ensure failure through punching shear or bending will not occur.

 

[apsix]

I would assume that it's not correct, unless informed otherwise by the designer.

 

[msquared48]

Sounds funny to me.

How is the attachment of the light pole made to the footing to develop the overturning moment capacity of the footing? Sounds like the only link to the footing from the lightpole is through shear...

Seems to me that rock bolts should be used here for better anchorage to the rockmass, in addition to the spread footing.

Mike McCann
MMC Engineering

 

[boffintech]

The pre-cast pole is to be placed through the two mats of rebar so that it rests on the dirt. There is a circle of vertical hooked dowels around the base of the pole extending about 4 or 5' above the top of footing. So there is a secondary concrete placement for what would look a lot like a pier in any other case.

 

[boffintech]

Just FYI, the EOR advised that the detail had been misinterpreted and that the bars were not to be cut. Just as we thought.