This is a common problem, and one that can be very difficult to remedy once the concrete is cured. As with most job-site fixes, the repair method depends on the nature of the problem and when in the construction process it is first noted. The repair method may be different if one bolt is out of place or if the entire anchor pattern has been misaligned. If the error is discovered before the column base plate has been fabricated, it might be possible to use a different pattern or even a different base plate.
If one or more rods in a pattern are out of alignment after the column has been fabricated, the easiest and most common repair is to slot the base plate, and use a plate washer to span the slot. If the entire bolt pattern is off uniformly, it might be possible to cut the base plate off and offset it on the column to accommodate the out of place bolts.
If the anchor rod or rods are more than a few inches out of position, the best solution may be to cut off the existing rods and install new drilled-in epoxy-type anchor rods. When using such rods, carefully follow the epoxy manufacturer’s installation recommendations, and provide inspection as required in the applicable building code. Take care to locate the holes to avoid any reinforcing steel in the concrete foundation. If any reinforcing steel is cut, a check of the effect on foundation strength should be made.
More detailed information can be found in section 2.11.1 of AISC Design Guide 1. It is also recommended that your project engineer should be consulted before any of these repairs are undertaken to make sure the best method for the specific application is chosen.
I have a question. I am currently attempting to write a procedure for verifying anchor placement/coordinates prior to erection of structure. How would I find an existing example to help me generate one?
@David- Apologies, but we do not have anything. Perhaps an engineering or detailing firm might have some information; we only manufacture the bolts, we do not have any experience installing them.
Dear Mr Dane,
While scrataching my head upon completely doing a perfect mistake, my small project site came to a show stop now. Anchor bolts of 1feet deep concretised, , but perfectly done well on a wrong orientation. The Structural team, beats with a hammer and says the orientation is a pin – joint type and need to shifted 90 deg. opposite for a fixed joint constraint. concrete set well.
The space on the other site has a 50mm space wide and 250mm . Can i drill two holes of the same dia 20mm and Epoxy grout it. Each pedestal needs 4 bolts like this and I have to do in 8 pillars. PL. ADVICE. Will it help. Structural guys grinding their teeth and i had hit a road block.
@Babu – Yes, if you are able to drill and epoxy anchors in the proper location, that is typically an acceptable remedy.
Hello sir ,
I have facing one problem , one of my friend he fixed the anchor bolts with wrong orientation for all collmun and fabrication is also done with the same base plate as pr drawing but the if the fabrication was not done we will rotate the base plate now whats the solution
@Abdul- The end decision needs to be approved by the engineer of record, but the options are typically; use post installed anchors, or tear out the concrete, fix, and repour.
HI Dane,
One anchor bolt at the corner of the pipe rack accidentally hit and bend. sub-contractor cut off the corner and replace the anchor bolt and proposing pour it with epoxy grout for the whole length of the corner around 1200x300mmx300m. My question is it acceptable to replace the corner with just epoxy grout?
@Leo- Per the AISC, replacing the anchor bolt with an epoxy anchor is acceptable. To determine if that fix, and the grout corner will work for this application, you will need to contact the project engineer.