Heated and Bent Anchor Rods

[NWK]

Concern:
On a current job site, several 1 inch anchor bolts/rods were poured into column pedestals out of plum. Construction workers decided to torch heat the anchors and bend the exposed 5 inches back to straight, with 17 inches imbedded in the concrete. The anchors have visible heat marks and some scortched threads. The concrete surface surrounding the anchors now has a glassy appearance. The anchors were bent to accept the base plates and are now being questioned by engineers as to how this heat treatment has affected steel properties. A tension load test has been requested, but not yet performed. Quality Inspection has proven to be poor on the site and the contractor wants a, "The anchor bolts are okay, no fix is needed," type of an answer. However, this answer cannot be provided without additional information. If anyone has good material science knowledge or has been faced with a similar problem, your comments on this subject would be greatly appreciated.

 

[evelrod]

I , too would be concerned and you will be remiss in your responsibilities if you do not REQUIRE a pull out or tension test! From what you describe and from my perspective as a retired Ironworker, you seem to be the victim of substandard work, at best, and shoddy workmanship bordering on criminal.(I was on top of a column that fell because a anchor bolt pulled out, so I am somwhat biased!!!)


With concern for the men who must "hang the iron",

Rod

 

[Rich2001]

If the bolts were fabricated from A36 steel - I would expect the tensile strength to be reduced by 20% due to this heat treatment. The thread hardness by a similar amount. To determine if the bolts are acceptable one must look at the reactions (forces) acting on the bolts and determine if the reduced strength is acceptable.

If the bolts were quenched and tempered then they should be replaced - no testing required!

If the anchor bolts are notch-tough steel - REPLACE!

If the anchor bolts were HSLA (high strength low alloy steel) - the heating will cause the grains to grow hence reducing its' strength - I would probally have these replaced.

I would expect that the concrete holding the bolts would also be weaked. Concrete holds a significant amount of water tand this heating would have remove this.

Overall, if in doubt, remove the achor bolts drill and grout new bolts.