If my already installed anchor bolts got bent by accident, is it OK to bend them back?

Damaged anchor bolts
Damaged anchor bolts

The anchor rods in this photo were damaged because they were covered with snow and the equipment operator did not see them.

Every situation is different, and we try to not make recommendations where bent anchors are concerned as we feel it is a question better answered by the project engineer, as he/she will be more familiar with the specific situation. That said, the AISC has this to say about repairing damaged anchor bolts:

“ASTM F1554 permits both cold and hot bending of anchor rods to form hooks; however, bending in the threaded area can be a problem. It is recommended that only Grade 36 rods be bent in the field and the bend limited to 45° or less. Rods up to about 1” in diameter can be cold bent. Rods over 1” can be heated to 1,200° F to make bending easier. It is recommended that bending be done using a rod bending device called a hickey. After bending, the rods should be visually inspected for cracks. If there is concern about the tensile strength of the anchor rod, the rod can be load tested.”

– 2nd Edition of the AISC Design Guide 1, under Base Plate and Anchor Rod Design

So field bending F1554G36 is acceptable as long as it is not more than 45°, and is it done per the parameters in the above paragraph. For other grades of anchor, or if the bend is more than 45°, the project engineer should be consulted in order to make the proper decision.

Written ,


    Dear Sir,

    We have casted in concrete M36 SS304 bolt. During installation, it was hit accidently by a cutter plate and it cut through the thread hence damaging the threaded area of the bolt. the length of thread damage is more than the depth of thread in its mating nut. Is it possible to deposit material on the damaged area to built back the bolt and subsequently thread it back to the spec required.
    Is it allowed by any code.


    @Usaid- We are not aware of any code that allows weld repair for this kind of situation, in fact it is usually prohibited. Replacing the bolt would be a safer option.

    Thanks sir for your prompt reply.
    Considering the amount of rework required as the bolt are embedded 1.5m into the concrete. We are studying option if any which is allowed by any code to reuse back the damage bolt. So far i have not found any code which allows that as such made me to ask an expert such as portlandbolt.

    Thanks again sir

    @David- Normally we are not too concerned with heating F1554g55 rods during manufacture, however multiple heating and cooling cycles may affect the steel in ways we are not familiar with. You would need to contact an engineer of metallurgist to be certain.

    PB1 type Anchor bolt site received.Some Anchor bolts (Quantity) Galvanize coating not proper/damaged if you possible repair or re galvanized …

    @Loilest- It depends on how badly damaged the zinc coating is. If it is minor, it can be touched up with cold galvanizing spray. If the damage is more extensive, you will need to have the bolts stripped and re-galvanized.

    We have installed stainless steel 304 anchor bolts (installed in concrete, cast in place) and they have to have verticality deviation no more than 1mm (measured on top). Some of them need to be bent just a few milimiters (less than 5°). Can we cold bend these anchor bolts considering ASTM F1554? Size of our anchor bolts are 30mm diameter.

    @Octavio- We do not have any guidelines for bending stainless anchor bolts in the field. Our guess is that a minor bend like you describe would not adversely affect the bolt, but the project engineer should be consulted for approval.

    @Amin- Per AISC guidelines, anything over 45deg is too far to be bent back, so an alternative method of repair would be needed.

    Can a 1-1/4″ diameter F1554 Gr 55 rod be bent 15 to 20 degrees using a hickey? How high is the risk of the rod being fractured or cracked at the bend? Thanks

    @John- The AISC guidelines only allow for the bending of G36 in the field. I do not see any huge issues with bending the way you describe, but you would need to consult with the project engineer in order to get his or her approval.

    Dear Sir,

    we fixed Anchor bolts Dia of 24 mm in Concreate. Anchor bolts thread length already have 100 mm.now we increase the thread length about 160 mm. kindly give me suggestion what machine of thread we use or any technich.


    @Barkat- You may be able to use a die nut, but you will need to contact a tool and die shop to see what your options are. We don’t really have any experience with adding thread in the field.

    This is our Elevator field. We use the M16 anchor fastner bolt. The bolt was broken at site at time of installation. So please guide us. Why the anchor fastner bolt broken. Can you say me

    @Dharmendra- There are many reasons why an anchor bolt can fail – anything from a bad bolt to improper installation to incorrect engineering. We are unable to pinpoint a reason for your failure without knowing all the information.

    @Ronelson- Typically speaking, A307A is made from a similar material as F1554G36. Therefore I would think that you could carefully bend your anchor bolt back into place. Heat can be applied to the bolt to help, being careful to not exceed the 1200F limit set by the AISC.

    if already installed anchor bolt broken, and also already installed steel structure column. then how we can rectify.

    @Anil – Depending on where it broke, and how many threads are left, you could possibly add a coupler and all thread rod, or perhaps a hole could be drilled and an anchor epoxied into place? It is hard to give a specific recommendation without specifics of the anchor.

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