Mechanical Rebar Couplers - Minimum end Distance?

[JoelTXCive]

We have a bridge column with #11 bars in it.

Per the plans, the column bars were fully developed into the bent cap. The contractor accidently cut some of the bars 1ft short.

The contractor's proposed fix is to add mechanical couplers to the bars and then have ~1ft extensions. (the extensions would probably only be ~8inches long assuming the coupler itself would take up some space)

What do you think?

 

[KootK]

Meh, I feel like the coupler setup would wind up adding nothing meaningful to the development length other than, perhaps, the coupler itself acting a bit like a localized anchorage device in bearing. And that suggests what might be a better solution if you have space and really want that lost development back.

 

[JoelTXCive]

Koot - That's exactly what we were thinking. The coupler might end up serving as a headed bar end.

We have not done any math yet, but it's possible that we do not need the full development length.

Another option is to just tell the contractor to find some headed bar ends that can be threaded on or grouted on.

 

[KootK]

Even with my solution above, the compression coming into the puck would have to kind of flow around the coupler. This is surely over thinking this but, then, that's kind of my thing.

We have not done any math yet, but it's possible that we do not need the full development length.

Very often you don't, depending on the detail. Or, alternately, full development never made a competent joint to begin with and that was just wishful thinking. Much depends on the particular detail.

 

[bugbus]

Does the design still work with some of the bars cut off? I have run into this situation in the past, where (usually luckily, but sometimes deliberately at design stage) we could afford to lose a few bars - either having insufficient development or cut off completely.

 

[phamENG]

Seems like the best way to preserve original design intent would be welding the bar extensions in place. @Enable

Whether or not preserving that intent is really necessary is, of course, another question and I think KootK covered that quite well.