Punching Shear Interaction with 2 Columns 1

[Feel_This_Moment]

Hello everyone,

A punching shear question: a project I'm currently working on contains a an RC slab that has one column bearing onto it from above and one supporting it from below as shown on the sketch attached.

I was wondering how the punching shear control perimeters of the 2 columns interact where they overlap and how this impacts the design of the reinforcement. This seems to be a bit of a grey area in the Eurocode so was wondering if anyone had done a design for something like this before and what they did.

It should be noted that the columns are too far apart to take a reduction in shear for partial comoressive transfer but not too far away that the control perimeters don't overlap.

Many Thanks

 

[slickdeals]

Treat each of these columns independently for the axial loads and moments they carry. It looks like you are transferring a column on to a slab.

 

[KootK]

I did a ton of work on this issue in this excellent thread on the same topic which includes the sketch below: Link

Depending on the particular geometry in play:

1) Strut and tie.

2) Independent punching frustums local slab flexure in between.

3) At intermediate distances, I feel a some version of a combined punching shear perimeter is appropriate.

Maybe take a spin through that thread and then report back here with any additional thoughts.

 

[Teguci]

CRSI - "Pile Cap design Guide" has a procedure for dealing with piles located near the supported column.