Anchor rod threads too high

[arrphoto]

A contractor installed the anchor rods too high such that the threads extend way above the base plate (by almost 3 inches). These were F1554 rods, but they bought them too long and installed them too high in the slab. He wants to install a stack of washers above the base plate to just above where the threads start. I've search and can't find any guidance on this problem.

Curt Fortenberry

 

[civilperson]

This is similar to angles used to tie down columns when the anchor rod extends above the top of the angles and bear on the angles through washers. (Angles are welded to the flanges of the column and aligned with the longitudinal axis).

 

[kslee1000]

The column base is potentially only one of the problems. Have you checked everything on top that will likely be affected by the 3" increase in elevation? Also, are you sure the embed length is as specified?

 

[arrphoto]

Thanks. I mistyped the part about them raising the anchor rod in the slab, I meant to say lowered it. But the washers are on top of the baseplate, acting as spacers to get the nut to bear on material as the distance between the top of the baseplate and the threads is a couple of inches. The contractor miscalcualted the lenght he would need (embedment, grout, baseplate, etc).

Curt.

 

[kelowna]

I have used washer plates in the past, no problems, usually ask them to be welded to the plate, but 3 inches is a lot.
If all the other bases are covered (capacity, embedment length, geometry, clashes with other items,...) I would accept the use of washer plates, but with conditions. I would use only one, maximum two plates (not 15), I would specify a minimum dimension (idally square, each sided twice the height plus hole size) I would weld them to the columb base plate so that they are secure and they do not shift and I would make sure that the anchor bolts are tighten as required.

 

[Lion06]

Didn't you get anchor rod shops to check?

 

[haynewp]

I don't know that I would noted the anchor lengths were too long on the shop dwgs as long as I saw that the minimum embedment and anchor sizes were met for structural purposes. He could have poured the footings thicker and had the threads where they were supposed to be.

 

[lkjh345]

Is there a shear, moment or tension reaction at the column base plate?

If there is no shear, moment or tension reaction on the plate, then I wouldn't be too upset over using a 3" high stack of plate washers to space up to the nut. I agree with kelowna as noted above: limit the number of individual shims they can use to 2 or 3 total, weld them to the base plate and to each other. But otherwise, the concept would be OK.

If there is shear, moment or tension on the plate, then things get a lot trickier.

 

[MiketheEngineer]

How about threading the rods down to where you want. Usually not too hard and fairly quick?

Assuming embedment is OK

 

[frv]

The first thing that popped into my head was MiketheEngineer's suggestion. Is there some clearance issue preventing the rods from being threaded further down?

 

[JAE]

Attached is from an AISC "Field Fixes" seminar I once attended.