29 C.F.R. 1926.755(b)(1), which states that:
Anchor rods (anchor bolts) shall not be repaired, replaced or field modified without the approval of the project structural engineer of record.
A rod that is found to be fractured or does not meet required embedment lengths presents a serious condition. This critical connection between the post and foundation has been problematic. In itself is not a serious deficiency as long as at least three quarters of the nut is engaged. If not, a coupler may have to be installed to lengthen the rod. This may involve complete foundation reconstruction. The first course of action is to see if the base plate can be lowered to fully engage the nuts.
One method of adding anchor rods is to drill through the base plate and into the foundation so that new rods can be epoxy grouted into place. If epoxy bolts cannot be used, you might be forced to use a mechanical anchor.
Welding may be precluded if the anchor rod is not weldable. Determine what the carbon equivalence of the anchor rod is prior to welding. . Fracture critical material critical installations and fatigue induced loading may impact welding Use the welding procedure for the anchors group of materials.