Need help setting achor bolts for 36" to 48" caissons!!

I am working on a foundation job where we I am laying out about 50 concrete steel reinforced  caissons.....25 of the require setting anchorbolts. I have done this once before with bad results. On a previous job I gave the contractor plenty of offset points for control to set the anchor bolts, I was even there when they set the anchor bolts...I pulled string lines, and measured swing ties...everything was good. Only to find out the next day that the contractor never fastened down the template and it shifted overnight. I assumed that the contractor was going to take care of this. So anyway I don't want this to happen again, so I would like some direction on how I should layout and set the anchor bolts, and mainly I want to come up with some kind of system so that every time I layout similar bolt patterns i can use the same template and be able to lock in down easily once it is in place. I am laying out 36", 48" and a few 60" caisons. 3/4" to 1" bolts with an average of 24" embeddment. the bolt patterns are either a 4 bolt pattern or an 8 bolt pattern.

Thank you!

--Caleb

The solution to the templates "moving overnight" is to be checking them first thing in the morning before the concrete is placed.

I checked the template after the concrete was placed.

I was actually there when they were pouring the caisson...so I made sure the template was set correctly and at the right elevation. It shifted between the time I had left in the afternoon and the next morning.

time to grab the superintendent and carpenter foreman in the field. tell them you can layout/stakeout/asbuilt until you are blue in the face, but they need to contribute as well. the carpenters should be pinning and bracing that templete once you say it is ready.

Generally a caisson has a top form, that could shift, so you must be careful in securing a template to only that.

Anchor bolts and baseplates are set to a whole variety of tolerances. The most forgiving is the requirement that the 4 anchor bolts fit through the predrilled baseplate. The base plate is set and grouted to elevation after the caisson has cured then the columns are set and welded into position. That sometimes involves inches of tolerance.

The architech/engineer may be expecting way too much.

That being said when I worked at Bethlehem Steel I laid out 356 anchor bolts on a 20'x50' CNC lathe foundation. It was a single concrete placement, 8' deep. The single piece lathe baseplate had 1/8" clearance at each bolthole. During the concrete placement a laborer put the concrete vibrator directly against one bolt moving it out of position. We had to drill that baby out and pour-rock in a replacement. Watching the millwrights set that baseplate was an interesting but tedious process.

BTW if they are pouting concrete, rest assured they do not not what they are doing. 24" imbedment is acceptable for a footer, but not a caisson.

Paul in PA