Concrete column joint 1

[drewtheengineer]

I'm searching to find out what, if any, codes apply to placing a joint in a concrete column.

The situation is that the top of a column had failed due to incorrect installation. A bearing plate was shimmed when it should have been grouted.

Anyway, one of the considerations is to level it off a few feet down and pour a new top to it.

The question is "What codes apply?"

 

[JAE]

If you chip the top section of concrete away to allow placement of a new section of fresh concrete, be sure that your column longitudinal steel is properly developed past the "joint" that you are creating. I would also specify that the existing surface be left rough (1/4" amplitude).

Check the shear that is going through the column at that point against shear friction. You might want to also add a bit more column ties - especially at the top if you have a bearing plate concentrated load. Many times we will specify three or four spaces of ties at 3" (75mm) o.c.

 

[benishak]

I have not come across some codes indicating proposed location of column joints (I would like to know if there is..)
Locating column joint is based on engineering judgement. As most columns are under compression, the decision to locate joint will be governed mostly by horizontal loads at that location as shear capacity have to checked (as mentioned by JAE).

 

[dlew]

drewtheengineer,

A joint in a column is not worse than a construction joint in a beam. See ACI 318, section 6.4. By the way in all buildings taller than one story, there are construction joints in the columns.

As JAE said, the longitudinal reinforcing steel has to be developed past the joint, and the concrete surface has to be prepared to transfer the shear (roughened surface or shear key.)