Heated and Torched 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.

 

[gdodd]

I suggest you repeat the torch treatment on a number of anchor bolts that have not been embedded in concrete and compare the mechanical properties and microstructure with bolts as received.
If the bolts are a high strength grade it is likely the torch heat treatment will have altered the properties in localised areas. In addition any protective coating if used will also be affected reducing corrosion resistance.

Good Luck

 

[arunmrao]

If the anchor bolts are high tensile bolts then torching is certainly going to hamper the properties. It would best be advised to simulate the torching on unanchored bolts and study the mechanical properties. Additionally any surface coating provided on the bolt may have been destroyed locally leading to localised corrosion prematurely.