Raise existing columns 8 inches

[twinnell]

Anyone ever had to raise existing columns 8"? One story retail with cmu walls on three sides and structural steel frames in the front. There are two or three lines of interior columns (steel). Roof structure is bar joists and joist girders. Structural steel and masonry are installed. Contractor realized that the roof joists are sloping too much and finds out that some of the interior columns are too short by 8 inches. Wanted to know if we could lift columns with a crane and add 8 inches of shim plates, extend anchor rods, and re-grout base plates. Anyone know of a better way.

 

[SAVAGE54]

As far as lifting the existing framing, I would defer to the contractor as a means a methods. I feel the top of steel can be raised by the following

A. Provide 8" tall Reinforced concrete pedestals at the base of the columns.
B. Shore the existing framing, cut the steel columns and full pen a 8" extension.
C. Install a shim along the girders. Such as a continuous tube, split tee section or other

I cannot tell from your question but I assume no finishes are in place that would be damaged during the lifting.

If you are required to design a lifting method. Remember to account for all of the addtional stiffness for the connections. The force required will be much higher then the calculated minimum dead load.

 

[rholder98]

Just curious--were the columns too short, or did he set the footings too low?

 

[valleyboy]

Can you extend the columns vertically at the top, and re-make the connection between rafters and the column head?

 

[twinnell]

I want to thank everyone for replying. It turns out the steel is correct, but the cmu walls where built 8 inches too high. So the joist bearing on the cmu doesn't have the correct slope...actually almost flat in back and almost 1/2 inch per foot up front.

Thanks again for the replies.