Splicing column rebar

[mattrams]

Hi guys. I'm new here just looking for some help please. Hopefully asking in the right place. I'm english but building in Indonesia.
Our builders have messed up a bit on house build and left the rebar short for splicing to new column on one column. We have 12 columns and the rest are OK. 16mm rebar so really needs a minimum spliced overlap of 64cm + from my understanding. We are in Indonesia so there are no building code issues, just want to ensure structural integrity even if not perfect.
The column in question is only 2.5m from another major column and will only have to carry its share of the part flat, part pitched roof. It probably carries the least load hence it was designed slighty smaller with less steel than most of the other columns. The column is 20 x 50 cm with 12 x 16mm rebar. The four corner rebars are all about 1m long which is good but the other vary from 20-45cm. And the spacing has gone very uneven. I know we cant weld new ones as it makes the steel brittle. Was thinking maybe tie the short ones together in a spiral with 6mm wire? Also extra stirrups, stirrups 10cm spec but could do at say 7cm spacing instead where the splice is. Also placing a couple of additional vertical bars in the large spacing?
No haters please. This is a developing country, just looking for a realistic solution. TIA

 

[^woody^]

Rebar is extended via wire tying. The overlap depends on the bar diameter and other factors but it's normally around 500mm

 

[mattrams]

Thanks but what i am saying is there isn't 500mm, thats the problem. I read overlap should actually be 40 to 50 x diameter depending on which source I was reading. So minimum 64cm. If you look at the photo all the rebar in the middle are short, one is only 20cm and the others range up to 45cm. Not much overlap. I was hoping the long corner bars would be a saving grace and maybe just strengthen the shorter bars with 6mm wire instead of the normal tying wire. Open to suggestions really

 

[noseall]

Thanks but what i am saying is there isn't 500mm, thats the problem. I read overlap should actually be 40 to 50 x diameter depending on which source I was reading. So minimum 64cm. If you look at the photo all the rebar in the middle are short, one is only 20cm and the others range up to 45cm. Not much overlap. I was hoping the long corner bars would be a saving grace and maybe just strengthen the shorter bars with 6mm wire instead of the normal tying wire. Open to suggestions really

Can you not drill and grout a (steel) dowel in?

 

[mattrams]

I had thought about that as wouldn't be difficult, but that column is choca with rebar. 2 beams connect to it at 90 degrees. Each beam has 4 x 16mm top rebars with hooks, then 3 extra 16mm bars about 5cm below them for added shear resistance. Not going to be able to drill 18-20mm holes without hitting the steel and compromising integrity.

 

[^woody^]

Well if you want to do it to UK standards then you'll need to drill the base. But then you really would need to check the rest of the build as there is no point in having one column to a better standard than all the other work.

Otherwise, check what the local standards are and see if that amount of overlap is acceptable. It may well be.

Strictly you need a local engineer's advice, as overlap is just one of several factors that influences design and failure risk.

 

[mattrams]

Its not really about UK standards. All western standards would include a large safety margin. Exactly how much i dont know. Here in Indonesia there are no standards or codes we need to work to for permits. This is purely for my peace of mind. Most builders here never even use 16mm rebar, normally no 10 wire or 13mm rebar for larger builds, so our build is over engineered by local standards. But they've just messed up on this one column.
I guess what I'm asking other than solutions is someone with experience saying that realistically in the real world n 4 x 1m spliced 16mm rebars in corners, supported with 8 x 16mm albeit shorter bars should be more than strong enough.