anchoring tension reinforcement (beam to beam)

[mats12]

Hi,

What is the best way to properly anchor rebars in situations like this - when you have beam to beam connection (beam are partly integrated with RC slab).

OPTIONS:

1) since i have pretty big rebars in diameter and they are pretty close together i dont think its a good idea to bend them upwards into beam 2 as shown in first picture,

2) i was thinking about welding another rebar at the end of tension reinforcement - rebars or maybe even a steel plate?

Tnx for help

 

[EZBuilding]

Unless you have some kind of moment reversal occurring, the bottom reinforcement would generally not be hooked at the support as shown in your sketch. The top reinforcement, however, should be hooked to develop it's tensile capacity as soon as possible.

 

[mats12]

top reinforcement is in compression, bottom is in tension... so i dont know if your suggestion is OK?

 

[hokie66]

Interesting that you say the top bars are in compression at the column joint. Are you saying that the net loading on the beam is uplift?

 

[mats12]

No, but since beam is heavily loaded it also needs top reinforcement in compression zone.

 

[hokie66]

Draw the bending diagram of the beam. The top is in compression at midspan, but not at the support.

 

[mats12]

hookie... yes that is true at column - beam 1 connection. but im asking about beam 1 to beam 2 connection (sketch). I dont think there is development of tension force at the top of the beam 1 there.

 

[hokie66]

Beam 1 would certainly have some top tension at that connection. The normal way of detailing the top bars there would be to extend them into the slab, maybe 600 mm.

 

[Klitor]

One could say that beam1 is not neccesary in this situation

 

[rapt]

Elastically, there would be torsion in Beam2 that would correspond with some negative moment in Beam1 at the end. Most designers would call this compatibility torsion and ignore it. So beam1 is pin ended and there is tension in the bottom.

Either way there is either a small moment or zero at the connection and with 25mm bars into a 250 wide supporting beam, I would have a hook at the end of the beam2 bars to provide adequate development for those bars where they are needed close to the beam1 connection.

I would provide a hook at the end of half of the bars are each end, so no bar has a double hook.