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Out-of-plumb anchor rods

Out-of-plumb anchor rods

Out-of-plumb anchor rods

I have a project where some column base anchor rods embedded in a concrete wall are out of plumb (noticeably at an angle). I looked in AISC Design Guide 1 and it seemed to suggest that as long as the column base plate holes could fit over the anchor rods, it's not much of an issue. If it does not fit the rods could be cold or hot bent (ASTM F1554) depending on their diameter. Steel erection hasn't begun yet and we have AISC-recommended oversized holes specified for the baseplates, so I don't know if it's going to be an issue or not. Just trying to get some guidance.

Is it generally acceptable for the anchor rods to be out of plumb provided that the column baseplate can fit over them and firm bearing against the baseplate can be obtained with the nut and washer?

RE: Out-of-plumb anchor rods

If they are at a noticeable angle, the nuts will not bear properly nor will they be able to be tightened sufficiently. If the rods are grade 105 they should not be heated, and it would be very difficult to bend them under these circumstances.

RE: Out-of-plumb anchor rods

Thanks TX. I probably should have mentioned that they are Grade 36 F1554.

RE: Out-of-plumb anchor rods

I'm trying to picture a column base plate in a wall. I guess it must be in the top of the wall.

What is the thickness of the rod in relation to the thickness of the plate and the grout space?

RE: Out-of-plumb anchor rods

Anchor rods are embedded in the wall - base plate is on top of the wall smile

Rod thickness varies between 3/4" and 1-1/4". Grout thickness below the leveling plate is 3/4". Plate thickness is approximately 1-1/2" +/- (depending on location). Why do you ask?

RE: Out-of-plumb anchor rods

Thanks. I was just thinking about the feasibility of bending the rods.

It seems like there should also be a washer shimming solution and perhaps a rod-to-plate welding solution.

Just thinking out loud...

RE: Out-of-plumb anchor rods

Is “Rod thickness varies between 3/4" and 1-1/4".” anything like anchor rod/bolt dia. varies btwn....? Round bars/rods have dia. and length, while rectangular bars have thickness, width and length, which is it. More specific words do have meaning. For the sake of clarity of description you might pick your words a bit more carefully. You say you’ve got about .75" grout, a leveling plate of unknown thickness, a base plate of about 1.5" thickness, plus the height of the nut on the A.B., plus some extension above the nut; that’s 3-4" of bolt extension above the conc. wall. Charliealphabravo’s basic thought was that you might be able to put two nuts on that A.B., one down on the conc. and the other up at the top of the A.B.; then put a heavy pipe over the nuts and see if you can bend the A.B. Also, measure the A.B. locations right at the conc. and study how those compare with your base pl., that is about how the A.B’s. might straighten up. The fact that the A.B. is a few degrees out of vert. down in the conc. wall shouldn’t appreciably effect its strength as an A.B. As mentioned above the A.B. must be perpendicular to the base plate or you will have trouble tightening the A.B. on the washer and base pl.

RE: Out-of-plumb anchor rods

Have you seen anchor rods that were not round? I'm not trying to be condescending...I'm honestly curious. I just assumed that "thickness" would be interpreted as "diameter".

RE: Out-of-plumb anchor rods

With the grout thickness at 3/4" there might be room to get the plate in there and level it ok. Might need some shim plates made for the nuts. Anyway to get a picture?

RE: Out-of-plumb anchor rods

Machined matching male and female rounded nut sets are available (Fastenal, Grainger, etc) in various sizes.

Expensive (5.00 to 8.00 dollars per set if I remember correctly) but if you only need 4 sets, they'd give you a alignment method for the off-angle anchor bolts going into a flat plate without stretching or stressing the relatively thin wall.

RE: Out-of-plumb anchor rods

Washer sets, not nut sets.

RE: Out-of-plumb anchor rods

1.25" anchors can be cold worked easily enough, especially Grade 36. The "process" would be - put 2 nuts on the top of the anchor (none and you'll damage the threads, 1 will spin and won't take a good strike) and hit with ~20 lb sledge.

The acceptability to engineering will be up to you to determine, if 'adjustment' is minimal, and the design connection had some extra capacity, I'd likely accept it. If otherwise, in the past I have allowed contractors to make their 'adjustments' or even cut off the existing, then add epoxy anchors to increase the capacity of the connection. In extreme cases, I have made the contractor demo and reinstall correctly.

RE: Out-of-plumb anchor rods

Are these anchors going to see any kind of real stress or are they basically just for erection?

I would treat bolts which are there just for 4-bolt OSHA anchorage very librerally. You might even build up some goodwill with the conctractor which you can use later in the project.

RE: Out-of-plumb anchor rods

JLNJ - the anchor rods at the braced frames (1.25" diameter) have some real stress in them due to uplift. However, you are correct, the remainder of the rods (3/4" diameter) are basically just to meet OSHA bolting requirements during erection.

As an update, steel erection began yesterday. Fortunately, the 1.25" diameter anchors are vertical, so there are no issues there. Some (half dozen or so) of the 3/4" bolts are at an angle as previously mentioned, but it appears that further slotting of the hole will allow the baseplate to be installed in these areas. The steel erector agreed that he could use some steel shims/additional plate washers to get full contact with the nut.

I truly appreciate everyone's input on this matter; it's what makes this website such a great resource. I'll keep you posted as erection continues.

RE: Out-of-plumb anchor rods

Use a couple of tapered washers (like those used on channel flanges.) By using two, you can rotate them to match the angle of the anchors.

RE: Out-of-plumb anchor rods

What about a weld washer? Leave them bent. Oversize the hole.. Use a weld washer. Done.

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