Assessment of existing socket for pre-cast concrete column

[quasiblu]

Dear All,
I am assessing existing sockets per subject for a very small addition on top of a structure and unfortunately I have stumbled upon a wrong rebar detailing for the horizontal bars in the socket walls, internal sides.
Let's see if I can paste a sketch.

Link

The horizontal bars in the internal sides of the socket are to be neglected.
I have seen some old book (not English, no copy/paste) saying that when the bending moment coming from the column is small (eccentrity/column side < 2), having horizontal bars just on the outer faces is acceptable (proven that their area is sufficient). This rule of thumb without the support of valid modern codes/authoritative lit/numerical checks is not something I would use for my assessment, and even if just 50% of the bars was enough (then excluded those that are wrong anchored), I am thinking that cracks may appear in many ways. This structure is very young, it still has to see the loads it's designed for.

Any of you that knows about refs that would say that horizontal bars on the inner sides can be avoided under special circumstances?

Thanks a lot.

 

[HTURKAK]

You did not mention if the pocket interior surface and column surface are keyed or not.. Your internet country code CZ if so ,
Eurocodes should be applicable in your zone..

As far as i know, EC-2 is silent for the subject horizontal bars on the inner sides .

I looked several documents,

- BetonKalender Precast Concrete Structures,

- Structural Precast Handbook

You did not mention your position for subject design . IMO, the designer should prove with calculation that if horizontal bars on the inner sides are not necessary..











Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[quasiblu]

Hturkak,
Area is middle East, American codes are applied.
There is a vague note on the dwgs for the vertical surfaces inside the pocket to be roughened.
For the records, if I consider just the horizontal reinforcement area at the outer sides of the pocket, the check that was put in the calculation report is no more satisfactory.
Anyways from your refs I understand that literature accepts to consider the system pocket+embedded bottom of columns as one element, hence no need in general of using neither horizontal or vertical bars on the inner pocket faces, which is an approach I can live with as long as it is justified by the geometry, and consequently by the structural schemas that fits best the geometry, and ultimately the checks.

Thanks a lot for your replies!

 

[quasiblu]

Ok, I have been thinking some more about this, and now I am of the opinion that the inner corners of the socket do not need detailing of concave corners.
That's because it is all filled with grout and concrete, so actually it is not a concave corner facing a void, no push to void is generated. That push is taken by what's in the socket.

Disclaimer: this is an exceptional interpretation for the assessment of existing sockets and I promise I will not use it for new designs.