Column Repair/Shoring
Column Repair/Shoring
(OP)
We have been asked to come up with a column repair detail and procedure for a column damaged by a contractor during a renovation. Two concrete columns sit back to back at a building expansion joint, 2" gap. The gap was filled with stuff/gunk, and in attempt to remove it they used a core drill. While core drilling they not only removed part of the concrete cover but also cut rebar at the top of the column.
Each column is 32"x16" with 6 bars on each of the long faces of the column and the bars on the expansion joint face of both columns were effectively 100% removed. The columns are near the bottom of the building and have factored loads of about 900 kips each.
Any thoughts?
Each column is 32"x16" with 6 bars on each of the long faces of the column and the bars on the expansion joint face of both columns were effectively 100% removed. The columns are near the bottom of the building and have factored loads of about 900 kips each.
Any thoughts?






RE: Column Repair/Shoring
The only two thoughts that I can come up with are:
1) Pour new columns alongside the existing.
2) combine the two columns into one column, if you can justify not having an expansion joint or otherwise modify the expansion joint.
Good luck to the contractor who caused this damage!
RE: Column Repair/Shoring
1. Steel plates Option
One could drill completely at the centers of the 32" faces and insert a steel plate at the expansion joints' side to be taken with nut + expoxy there. Either the plate goes to the upper level to deliver proper tensile transfer or you provide by drilling the same.
2. Substitution of the entire column
You may do with proper shoring.
3. Adding additional steel members and parts
Some Shapes adequate to the problem may be added. One can ensure transfer of the tensile force by drilling into the sane columns.
RE: Column Repair/Shoring
RE: Column Repair/Shoring
RE: Column Repair/Shoring
The shoring was so tight that when the sun hit the 4 inch pipe, the reading on the jack would go up a couple of thousand pounds.
When you say 900 kips factored, what is the actual dead and live load? If you can design a shoring system for 200 kips or so (unfactored dead load), maybe replacement is the best way.
RE: Column Repair/Shoring
I have the following suggestion assuming you can solve the accessibility issue:
1) Shore the column that has the rebars cut, you can probably use two W14 Column Section on both side of the damaged column at the underside of the spandrel beams delivering the shear. Install cap plates at the end of the W14 section and use tapered shims welded in place after a tight fit. you might want to do the same at the floor above since there is also a load coming down from the upper floors.
2) dig 2 inches around all the cut rebars.
3) use a CADWELD(R) Rebar Splicer [or equal] to reconnect the cut bars.
4) Form and Inject high strength non-shrink / non-metalic grout to original Column shape and size.
RE: Column Repair/Shoring
Use the google search at the top of the page.