RC beam to RC wall connection

[hoshang]

Hi all

I searched the thread but I couldn't find a similar subject.
How the RC beam to RC wall connection be detailed if the wall is spanning up the beam for several floors, while the beam is spanning from one column to the other column (passing the wall between the two columns)?
This concerns to the congestion of beams and walls re-bars in the region of the connection.

 

[KootK]

- Beam top steel will run through.
- Beam bottom steel will probably also run through.
- I'd stop the beam stirrups at the faces of the wall.
- I'd just discontinue the wall reinforcing at the beam to keep things simple. Depending on member sizes and density of reinforcing, it might not be a big deal to run the wall bars through the beam but, if you're going to go that route, I'd at least sketch up a decent scaled detail to convince yourself that it constructable.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[rapt]

Disagree on the last one. I would definitely NOT discontinue the wall reinforcing at the beam. Especially without knowing a lot more about the design!

 

[KootK]

I would definitely NOT discontinue the wall reinforcing at the beam.

Why ever not? Sure, everything has to be designed and I can imagine some exotic situations where it might be problematic. However, for the general case of a little beam passing through the interior of a big old bearing wall, discontinuing a few bars surely wouldn't make a lick of difference. Especially in the common case where the beam is at a floor level.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[hoshang]

Hi all

- I'd stop the beam stirrups at the faces of the wall.

Can partial bearing of beam on the wall (if the wall thickness is less than the beam width) exclude stirrups (shear strength) from the beam? do you consider vertical wall re-bars as legs for stirrups? I think partial bearing of beam on wall will decrease flexural reinforcement demand.
My thought is that the beam stirrups can be stopped if the wall is located near the center of the beam. If so, How about wall located near the columns?
What about compatibility torsion requirements for beams supporting discontinuous slabs? This requires stirrups additive to shear reinforcement (or side longitudinal re-bars).

- I'd just discontinue the wall reinforcing at the beam to keep things simple.

After pouring concrete, do you drill/epoxy wall vertical re-bars on the beam for the next floor?

 

[KootK]

I’d recommend posting a sketch so that we can understand your situation. It doesn’t Sound like what I’d envisioned (beam passing through perpendicular wall with full bearing).

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[hoshang]

Hi

I’d recommend posting a sketch so that we can understand your situation.

 

[jayrod12]

I believe that is entirely different than what Koot was envisioning. Is the wall supposed to support the beam? or is the beam designed to span from column to column?

 

[hoshang]

or is the beam designed to span from column to column?

Yes the beam is designed to span from column to column

 

[jayrod12]

Can the wall and it's foundation take the load from the beam?

 

[JAE]

The beam will not span from column to column if the wall is there. The wall provides some level of bearing, stiffness and support. Unless you separate the beam from the wall with an expansion joint (which would not be the thing to do in my view), you have to consider the beam as spanning from column-to-wall-to-column.



Check out Eng-Tips Forum's Policies here:
faq731-376

 

[BAretired]

The sketch is still not clear. What supports the three walls which do not rest on the beam? Do they run down to foundation level?

BA

 

[JAE]

I think this is a plan view BA. With four walls (supported below by some type of foundation along with the two columns.

Sort of a floor beam running parallel to and through and elevator shaft wall.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[KootK]

From the perspective of the design and detailing of the beam, I'd be inclined to treat the wall as a large column and design the beam as two span continuous.

Can partial bearing of beam on the wall (if the wall thickness is less than the beam width) exclude stirrups (shear strength) from the beam?

I'd say so. You couldn't really fail the beam in shear without also mobilizing the wall in shear. This may not apply at the roof level where your ability to keep the beam tied down tight to the wall is less apparent.

do you consider vertical wall re-bars as legs for stirrups?

You could but it seems unnecessary. You'd also have to combine the shear demand with any other demands on those bars arising from their role as wall reinforcing.

I think partial bearing of beam on wall will decrease flexural reinforcement demand.

It will absolutely reduce bottom steel demand. It adds top steel demand.

What about compatibility torsion requirements for beams supporting discontinuous slabs? This requires stirrups additive to shear reinforcement (or side longitudinal re-bars)

You do need to deal with that eccentricity somehow and tailor your detailing to reflect that. It might be easier to rectify your beam torsion via slab flexure.

After pouring concrete, do you drill/epoxy wall vertical re-bars on the beam for the next floor?

As it happens, in this particular case, I agree with rapt that you should run your vertical bars through the beam. I imagine that you're using your walls as lateral load resisting elements? Shear walls?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[jayrod12]

I wouldn't be surprised once you consider the beam only spanning the short distance, you couldn't reduce it's thickness to match the wall thickness. It might run into the column at a slight eccentricity, but I can't see that impacting the columns significantly.

 

[BAretired]

I think this is a plan view BA. With four walls (supported below by some type of foundation along with the two columns.

Sort of a floor beam running parallel to and through and elevator shaft wall.

If that is the case, perhaps two beams could be used, each bearing on one corner of the elevator shaft (if that is what the square thing is).

I was under the impression that the wall above the beam did not extend down below the beam, so that the beam was supporting the wall.

BA

 

[hoshang]

Thank you all

I think this is a plan view BA. With four walls (supported below by some type of foundation along with the two columns.

Sort of a floor beam running parallel to and through and elevator shaft wall.

Exactly.

If you can provide a sketch of your suggestion for the case stated in the first post. What one should do? Have you encountered such a problem?

 

[KootK]

If you can provide a sketch of your suggestion for the case stated in the first post. What one should do? Have you encountered such a problem?

- Have.

- I recommend doing what I described.

- How about you sketch it up and I'll let you know if anything looks out of wack? No time today for homework assignments.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[hoshang]

- How about you sketch it up and I'll let you know if anything looks out of wack?

Please find the attached picture

 

[BAretired]

What the heck is that?

BA