I do not think there will be any tension, just vertical shear (between the nut and the rod). I am not aware of any limitations on such type of connection - it is an equivalent of welding a plate to a rod.
I also believe that if the nut is tightened against the baseplate and then welded, the load will be shared by the available threads and the weld.
The original posts indicated that coupling and enlarging of bolt holes are not a viable option.
V. Steve Gordin, SE
----- Original Message -----From: Tarek MokhtarSent: Tuesday, June 23, 2009 12:09Subject: Re: Anchor rods set too low (again!)Steve,I do not think you can get any values for tension in a plug weld, enlarging the hole and adding a coupleris how I have done it in the pastTarek Mokhtar, SECan you weld the rod - as is, below to the top of the nut - to the nut?SG
----- Original Message -----From: Drew MorrisSent: Tuesday, June 23, 2009 10:42Subject: Re: Anchor rods set too low (again!)Unfortunately, there is only about 1/8" to 1/4" of clearance between the anchor rods and the inside of the base plate holes. I need the connection to be good for about 45k (strength).
SGE Structural wrote:
Drew,Welding of this steel does not appear to be a problem. You may not need an extension: a 1/2" thick weld of the 1-1/4" rod to the baseplate (inside the hole) will be good for about 45K (LRFD). This may be sufficient even without claiming the combined action.V. Steve Gordin, SE
----- Original Message -----From: Drew MorrisTo: SEAINTSent: Tuesday, June 23, 2009 10:15Subject: Anchor rods set too low (again!)I have a case where the anchor rods have been set too low (again). They are F1554-36 1 1/4" diameter. To make things worse, the columns have fixed bases and have been installed with the grout below the base plate installed. I'm not sure why the contractor even bothered to call this in this late.
Typically, if the rod head is flush with the top of the nut, we use the full strength of the rod. Is there a way to determine what the connection strength is between the nut and the rod if less than the entire rod is engaged? I can't enlarge the holes in the baseplate for couplers without affecting the anchor rods and I am leery of welding on an extension of the threaded rod.