Question about 'Drop beam' - Wall connection

[TarikHKJ]

Hi

(Metric Units)
What is the detailing for the connection of a drop beam (B=60 H=70) on a bearing wall (width=40 cm)
the beam is dropped 35 cm below the solid slab (thickness=35 cm) ?

Is it ok to load a drop beam on a wall with no embedded column in the wall section?

the beam bottom steel is 18$25 (on 3 layers, 6 bars each)


Thanks so much and sorry for my English.

 

[msquared48]

Depending in the load, size of the wall and beam, I would not leave column steel out.

Mike McCann, PE, SE (WA)

 

[TarikHKJ]

I will post shop drawing later since I dont have them now,

what do you mean by 'I would not leave column steel out'?


Regards

 

[KootK]

A critical issue with wall bearing beam joints is getting sufficient anchorage of your bottom bars beyond the face of the wall. 40 is a good thick wall but, then, three layers of 25M is a fair bit of reinforcement. Some questions for you:

1) has any flexural fixity between beam and wall been assumed?

2) do you know the beam reaction at the wall?

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.

 

[msquared48]

I meant that I would leave the column steel in the wall.

Mike McCann, PE, SE (WA)

 

[KootK]

When you've got wall extending on both sides, there's a lot of axial capacity there, even without adding an integral column. So, depending on load, you've got a few options:

1) Use the wall with no integral column and no special wall reinforcing beneath the beam.

2) Install an integral column that projects from the wall a bit.

3) Leave the face of the wall flush but install a column rebar cage inside of the wall for extra capacity.

I believe that msquared is proposing #3. It's a great system as you get extra strength without complicating the wall formwork.

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.

 

[TarikHKJ]

@KootK you make perfect sense. I dont have the shop drawings with me now, will upload here asap. this is a basic sketch i just draw

https://www.dropbox.com/s/ofya6t2ovva9xjd/beam wall sketch.dwg?dl=0

@msquared48 There is no column steel in the wall, wall reinforcement is just 5Y16/m, basic sketch:

https://www.dropbox.com/s/ofya6t2ovva9xjd/beam wall sketch.dwg?dl=0

 

[KootK]

Any chance you can post PDF sketches? I'm on holiday and don't have access to CAD.

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.

 

[TarikHKJ]

@KootK Sure, here's the PDF, tell me if there's a problem with quality.
its a bit trickier since the existing wall is already there and there is only 1.8 m of it not yet poured.

PDF with longitudinal section :

https://www.dropbox.com/s/bfjw7o1z6mn3x8k/beam wall sketch-Model.pdf?dl=0

 

[KootK]

Thanks. What is your beam reaction at the support?

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.

 

[TarikHKJ]

Will get back to you with that later, maybe tomorrow,

was just looking forward to know initial hunch, is it sufficiant to add column reinforcement to the wall section only 1.8m high under the beam?

 

[KootK]

My hunch is that it would be sufficient if there's a stretch of wall on either side.

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.

 

[TarikHKJ]

yes there is a stretch of wall on either side of the beam, but is it sufficient without planting a column?

 

[KootK]

I know of no way to know for certain without performing a structural engineering demand/capacity check.

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.

 

[hokie66]

I agree that more information is needed, and in any case, our blanket approval means nothing. But unless this beam and wall are part of a moment frame, it is likely that your bearing condition will be fine. Is the beam pocketed into the wall, or does the wall stop at the beam soffit?

But the design would seem to me to be poorly proportioned. That is a lot of steel in a 600 wide beam web. Why not make it wider so you can get the steel all in one layer, or two at most? And the reinforcement in the 400 wall sounds light.

What does your mentor say about the situation?