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.

 

[GRPatel]

What is the material of the anchor bolt. What is the strength you have been looking for from the anchor bolt? Unless this is indicated it is difficult to respond.

 

[NWK]

The designer has informed me that the unfactored loads on each anchor rod is 21 kips. The anchor bolts are Quenched and Tempered and apply to ASTM A449. Many anchor rods throughout the project have been tampered with, but in this particular case they are imbedded in an incorrectly formed pedestal without proper edge distance. The footing will be removed and rebuilt for sure. Because it is being removed, it was suggested to perform the load test on these bolts. The allowable load on each rod is 31 kips. Therefore, it was suggested to test them to 26 kips, the average. If it reaches this level, the test will be stopped. If it snaps prior to this, the heating and bending had ill effect. Most likely, due to unproper edge distance, the concrete will fail prior to the anchor. This is a large steel framed-structure designed with shear lags in the perimeter columns. This is new terminology to me, being a young engineer, but the structure is a large open hanger-type building.

 

[Rich2001]

Being Q & T bolts I would have them replaced.

 

[GRPatel]

I made a few calculations based on your inputs. I assumed that kips is kilo pounds. The stresses I get are within limits of popular structural steel (Fe410).