Hello soilschick, as John already stated, many of the codes will not allow for the sort of additions that your pictures have shown. In particular, D1.1 definitely doesn't allow the sorts of things that you have there. The other thing that wouldn't follow the code would be any of the use of a "60" series welding electrode for welding on structural other than decking materials. If there were any exceptions to these sort of things they would have to be noted exceptions by the EOR.
     In another post you had spoken of tilt-up concrete construction. There is a practice that is used in this case where the vertical wall panels will be connected with a plate that I know of by the name of a "butterfly connector". It is usually a 1/4" to 3/8" plate that is roughly 4" square with a 5/8" hole in the center of it and then it is sheared from the outer edge of the center of one of the sides to the center hole, allowing one edge to be split so that it can be driven into the crack between two of the imbeds and allow the two opposing edges to be welded to each of the walls that it is connecting. This is a different sort of case than the things that your photos are showing on a structural steel application. This connection point is also different than the connection that will be made where the vertical panels meet the footings or the floor. If there is a gap at this point it is not acceptable to slug, use bar stock as a spacer, or use a "dutchman" as some other folks refer to using additional filler other than weld metal. Instead it is expected that a weld padding process will be used to fill the gap and that any specified weld size will be met by the addition of beads until this has been accomplished. Just a few more thoughts for your consideration. Best regards, aevald

Just saw a few more of your pictures, WOW those are some real doosies!