Embedded Pole

[NewbieStruct]

I am reviewing a shop drawing for sign foundation. The two steel pipes supporting the sign go 15'0 below ground level and 25' above. The contractor is asking about the means of holding the steel pipes straight while pouring the concrete around it at the foundation level.

He does not want to use two cranes to hold the steel pipes (a suggestion by a senior engineer at my firm) as that would increase the construction cost.

I am guessing I could design a splice but I am not so sure about my approach in doing so.

 

[msquared48]

Can you try another foundation design?

Consider using two poured oncrete caissons with rebar cages, and embedded anchor bolts for the sign. Design a new base for the sign columns to fit on the caissons and attach to the anchor bolt pattern. This will make it possible for the use of one crane to do the lifting and placement.

Otherwise, the contractor would have to guy off the assembly while the crane was holding it to pour the concrete, and while it cured to a sufficient level to be safe. Lots of crane time.

Mike McCann
MMC Engineering

 

[BAretired]

I agree with Mike. Use baseplates and anchor bolts instead of embedment.

BA

 

[MiketheEngineer]

If you must use embeddment - just make a tepee of wood - like scaffolding to hold the pipes vertical. Done all the time.

 

[a2mfk]

Though I agree with Mike that is a fairly common sign, post, traffic light pole, etc. way of doing it, the GC bid this design, go the job, and now he wants you to figure out how he can do it? That would piss me off unless someone was paying my ad serv...

 

[DWHA]

This does not appear that difficult to do. Temporary shoring is a method of construction up to the contractor unless defined in the contract documents. If he wants to change the foundation or add a splice, ask him for a drop in his bid price.

 

[TXStructural]

Embedding a pipe is a recipe for corrosion problems. That said, if a contractor cannot figure out the mechanics of propping up a pole to be embedded, they are probably not qualified to perform the work. We could all engineer a solution, but if they think a crane is expensive...

Be sure they do not just set the pipe/pole on/in the soil at the bottom of the hole, too. It should be held above the soil by the topside props or by a precast or similar support at the bottom of the hole.

 

[Splitrings]

If it has to be embedded, I would consider a 15' or slightly longer sleeve in the foundation. No doubt the wind will start to blow if you try and use 40' steel pipes! The other advantage to the sleeve is you could replace the sign poles after a vehicle runs into your sign.

I think it is more typical to use anchor bolts and a base plate.

 

[msquared48]

OK, but what gets me is why is the contractor wondering about that now? He should have had a plan to do this long before now that was figured into his bid. Is this T & M?

Really, this is his problem, not yours.

Mike McCann
MMC Engineering

 

[dik]

With a frangible top coupling, like light standards, so that the top can be replaced.

Dik

 

[a2mfk]

I meant to ask if this if for a private owner, not a roadway structure I hope?

 

[NewbieStruct]

Sorry guys I had to leave work for a personal emergency.

We finally decided to lay it on the contractor as msquared had suggested.

a2mfk - it is a project for a private owner