CIP Concrete Column Splice
CIP Concrete Column Splice
(OP)
My typical concrete column detail shows the main bars for the "lower" level column with a sweep in them as they pass through the beam above and extending as dowels for the columns at the level above. I have a contractor that ordered straight bars that stop below the bottom of the beam. He wants to use dowels that extend into the low column, through the beam and into the high column. I have never used this type of a detail. Any insight as to experience with this situation or design concerns would be appreciated.






RE: CIP Concrete Column Splice
The other issue is that with the splices, your "dowels" would be set inside the main column bars and thus, at the floor level your "d" of your column would be smaller than the typical "d" of your columns beyond the splice.
This usually occurs anyway with 1:6 tapered column bars extending up through the floor depth and lapping with upper column rebar just above the floor.
We usually avoid this by moving the laps up into the mid-height of the column (see this discussion: thread507-298261: column reinforcement - crank on top or bottom?)
RE: CIP Concrete Column Splice
Starting lap splices at the top of slab is the economical way. This allows the upper cage to be set directly on the concrete surface. Starting splices mid-height required some way of securing the upper cage in place before forming. Tie wire is not really made for this kind of stress, and falling rebar cages are dangerous. If you use mechanical splices, splice them at a height above the slab to give workers good access. The offset bends in the longitudinal bars should start inside the floor beams/slab and be complete at the top of slab.
RE: CIP Concrete Column Splice
See attached sketch
RE: CIP Concrete Column Splice
RE: CIP Concrete Column Splice
My columns are square. Are you suggesting that Config A is better than Config B on the attached sketch?
Thanks.
RE: CIP Concrete Column Splice
RE: CIP Concrete Column Splice
As for reversing the usual scheme and putting the offset on the upper cage, it is perfectly acceptable as long it is detailed sufficiently in the CD's. That said, since it is non-standard, I recommend that you discuss it with the contractor to be sure it gets done correctly. Things done in a non-standard way are more likely to get built wrong.
RE: CIP Concrete Column Splice
RE: CIP Concrete Column Splice
Unfortunately all too often special inspection just goes to the lowest bid who then progresses to not keep the engineer in the loop on anything. If they even show up at all.