Column Anchor Bolts

[DRW75]

Hey folks,

I've got a project whereby I am relocating an existing building to a new location. It seemed to me the best way to do this is to pour the foundations(and piers) without anchor bolts, and then match-drill the concrete once the columns are in place via crane as required. I just wanted to make sure that there weren’t any big issues with this... I've called out chemical anchors which are sized as are needed, but from a construction feasibility point of view, what would be a big downfall with this way of setting columns?

For a new construct, I would call out standard anchor bolts as there will be play earlier on, and the error/discrepancies can be made up with slots and the like.

I just think that if I try to get the anchor bolts as they were in the original building location, they would never match up close enough, and there would be problems then for field fit-up

Thanks for the comments/suggestions

DRW

 

[UcfSE]

Will there be any stability or safety issues due to the fact that the columns will be set before the chemical anchor hardens enough to hold its own?

 

[samdamon]

drw75-

Assuming that your chemical anchors have been properly designed for the forces they are to carry, the big issues to be careful about IMHO are the practical ones that always arise when using adhesive in the field.

Most structural adhesive mfgrs provide detailed instructions about how anchors are supposed to be installed, including minimum embedment depths, concrete hole diameters, hole cleanliness, minimum set times before loading the adhesive, and maximum tightening torques. Make sure these directions are followed carefully.

If the Contractor uses compressed air to blow debris out of the holes make sure there is no oil in it. Blow some air on a test piece of cardboard to check.

If the weather is very hot or cold this will affect the set times of the adhesive.

Good luck!

 

[DRW75]

UcfSE
The erectors should certainly consider the fact that the chemical anchors require about 30 minutes to come to full strength - meaning all temporary bracing, rigging, crane work must be maintained until duration is up.

SamDamon
I'm not a terrible big fan of chemical anchors, but it seems like the best alternative for this particular project (versus miss-fit of threaded rods). I'm not very keen on mechanical anchors with the wedges and the like - don't know why (worried about spalling concrete by overtorqing I think), but I put a bit more trust in the epoxy for some reason. Of course notes have been added to the effect of following manufacturers installation procedures.

Thanks for the thoughts people

DRW

 

[14159]

What is the lateral system? If it's something that requires a great deal of force to hold a column down, then you might have a hard time getting the adhesive anchors to work. For example, I'm thinking about some base plates that I've designed in the past that required 1.5" diameter, 20"+ embedment, quite a task for an adhesive anchor.

DBD

 

[TPNY]

Would it be poosible to embed a plate in the concrete (mechanically attached with embeded anchors into the crete, or something) and then weld the columns to the plate? This way you can be off by even a few inches, and as long as you can get enough weld between the plate and the columns, you should be ok.

 

[SlideRuleEra]

A version of Zo40's embedded plate is frequently used during power plant construction. Studs are typically welded to the plate, instead of being mechanically attached, however. Concrete has to be consolidated carefully around & under the plate, but it is doable.

I have done what you are suggesting (chemical anchors, after concrete placment), but only for lightly loaded structures. If you go your proposed route, make sure the holes in the base plate are properly size (large enough) to allow the drill bit to pass though - a detailer might miss this requirement. This may be somewhat larger than a standard or even an oversized bolt hole.

http://www.SlideRuleEra.net

 

[elpoblano]

DRW75,

You could also pour your foundations and the a. bolts as per the original design of the old building, and using plastic sleeves to allow some movement on the a.bolts. Check with the anchor sleeve manufacturer, the maximum permitted movement.

Erect the columns and grout the base plates, filling the sleeves. This method may need the ocassional oversize hole on the base plate.

On the other hand, your initial solution of using chemical anchor bolts is very adequate. A. bolts' length is not much of a task if you have ever installed a 16 ft. long chemical rockbolt, resin anchored on its full length. They are used extensively worldwide. Just follow the manufacturer's instructions carefully.

 

[transmissiontowers]

Could you only pour the new foundation part way up to the bottom of the anchor bolts? Move the old building to the new site and place it on cribbing. Put the a.bolts in the beam/column above the partial foundations and pour the concrete up to the bottom of the beam. Remove the cribbing when the concrete has cured.

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