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Bearing Area Shear Wall on Column

Bearing Area Shear Wall on Column

Bearing Area Shear Wall on Column

(OP)
Hi All

I have a wall resting on columns.
The column has a column "head" that coincides
with the angle of the compression strut and also
have a slab thickening under die wall. (see attached sketch)

The bearing area is a bit of the issue. Do you take it as the
width of the compression strut mulitply the wall thickness or
can you use a bigger area ( picture under column) since
there is a slab thickener?

Kind regards

RE: Bearing Area Shear Wall on Column

Quote (SteynvW)

Do you take it as the width of the compression strut mulitply the wall thickness or can you use a bigger area ( picture under column) since there is a slab thickener?

For bearing on the wall side of the interfaces, you would use the thickness of the walls. For bearing on the beam side, you could probably use the same thickness but a higher f'c based on confinement. I've sketched up some thoughts below.

I question the efficacy of the corbel strategy. It will complicate formwork, work your columns pretty hard, and and may not alleviate all of your bearing issues. That said, I know that we've discussed alternate strategies at length in your previous, related threads. If you say the corbel's the way to go, then I'll do my best to help you get it sorted.



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.

RE: Bearing Area Shear Wall on Column

(OP)
Hi Kookt

As always I appreciate your input (really enjoyed you rebar development around corners discussion, we also have provisions in our code for it). As far as the rest of the structure
goes almost everything else from beams to slabs to stairs and piles have
been completed, this is just the final puzzle to crack.

After some arguments with the Architect and the QS I have convinced them
to increase the thickness of the wall (more of a spacial than a cost issue)
but not enough to get the required area in my strut without sending reinforcing through the roof.
So if I cant have thickness I have to have width and with this corbel I can get the required width without hampering the the layout or the adjacent parking.

Quote (kookt)

"work your columns pretty hard"

Are you concerned about the eccentricity (hence a extra moment) it will
create on your column?

Kind regards

RE: Bearing Area Shear Wall on Column

Quote (SteynvW)

Are you concerned about the eccentricity (hence a extra moment) it will create on your column?

Precisely. That said, if it works... it works. And reviewing your geometry, the eccentricity doesn't look that bad anyhow.

If one wished, another approach could be to treat the portion of the column with the corbel as an element cantilevering down from the wall above. Then a pin could be assumed at the bottom of the corbel and the column segment below assumed to have no load eccentricity. My guy tells me that might be closer to the truth of things given the relative stiffnesses of everything.

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.

RE: Bearing Area Shear Wall on Column

(OP)
I have accounted for the extra moments in the column,
but like you said if it works it works.

I have a setup where my column is not on the edge of the
wall and move more towards the middel. (see attached)

By inspection this transition zone should work better, but
I am struggling to form a correct Strut and Tie model.

I have made a couple of sketches and I think option one
is not that far from the truth if I compare it to my
plain stress analysis. With the exception that the half half
force should be more like a two thirds one third distribution.

I know 3 is not in equilibrium but from a practical point of view
I reckon it can also work.

Do you think it is a accurate approximation?

RE: Bearing Area Shear Wall on Column

I like model number one with the loads adjusted to be in equilibrium with your column reactions etc. Model three doesn't capture enough of the cantilever behavior in my opinion.

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.

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