question about reinforcement

[mats12]

Greetings, Not my field so I have to ask...

I have RC wall 250 mm in thickness (basement) and above it is RC slab and a RC column 300 x 300 mm in upper floor.
Ancors (rebars) for column are installed in RC wall. Since wall is 250 mm thick and column is 300 mm (concrete cover is the same for both - lets say 35 mm) Im asking what to do about anchors-rebars?

case 1) to bent inner anchors so there will be no difference when it comes to overlaping rebars
case 2) dont complicate and leave anchors-rebars straight

I have looked in Eurocodes and it is stated that rebars (overlaping)can be apart for max 50 mm or 4 x diameter of rebar (whichever is smaller value).

Your take on this?

thx

 

[jayrod12]

I'd be pouring a pilaster in the wall below, or at least a corbel to give you a chance to make the horizontal job in your rebar in your slab.

 

[mats12]

maybe i shouldnt said column... what about we have a RC vertical tie instead of column? So there will be no significant vertical load acting on small area?

 

[KootK]

I'd go with option two and provide some concentrated ties at the offset lap splice. It's simple to build and should be in compliance with codes if the concentrated ties are detailed properly to make it a reinforced concrete joint rather than just an un-reinforced offset lap. At the proportions that you've drawn things, I would consider option one to render the offset rebar running through the joint useless. Your concrete stresses around the bends would be too high and would generate crushing. And, at the end of the day, what's the point of having rebar that you can't actually use?

 

[BridgeSmith]

I agree with KootK about not bending the bars in the slab.

I would add that the effective depth of the reinforcing that dictates the bending capacity for the bottom of the column will be based on where the reinforcing shown in red is located.

Rod Smith, P.E.

 

[hokie66]

KootK and HotRod10 are correct.

The outside starter bars need to be positioned in the wall to allow for the column ties. I would also place cogged starters in the slab for the inside column bars.

 

[mfrad]

An alternate is to make the column 250 x 300 flush with the foundation wall and increase column f'c to carry same vertical load. Check bending moment reinforcement in the foundation wall to match vertical column steel.