Punching shear and one-way shear for closely spaced columns
Punching shear and one-way shear for closely spaced columns
(OP)
Hi,
I have a scenario at the expansion joint of building where 4 columns meet. These columns are supported on spread footing (I would rather call it a mat foundation). The foundation is 2m deep and the spacing between the columns 750mm. So, the punching perimeter for individual columns over lap from the other columns. Can I assume the perimeter for punching shear and the one-way shear as shown in the image below. Is there any source which talks about such situations?
I have a scenario at the expansion joint of building where 4 columns meet. These columns are supported on spread footing (I would rather call it a mat foundation). The foundation is 2m deep and the spacing between the columns 750mm. So, the punching perimeter for individual columns over lap from the other columns. Can I assume the perimeter for punching shear and the one-way shear as shown in the image below. Is there any source which talks about such situations?






RE: Punching shear and one-way shear for closely spaced columns
Jason McKee
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RE: Punching shear and one-way shear for closely spaced columns
Thanks
RE: Punching shear and one-way shear for closely spaced columns
RE: Punching shear and one-way shear for closely spaced columns
As an oldish professor I know well would say, Engineering judgement is required in the application and interpretation of design codes!
It is not flexural, it is a deep beam/strut tie condition. There is no punching between the columns, only possibly for the whole group depending on the edge distance from the group. Treat it like a pile cap!
RE: Punching shear and one-way shear for closely spaced columns
RE: Punching shear and one-way shear for closely spaced columns
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: Punching shear and one-way shear for closely spaced columns
This is similar to the punching shear check required for a pile cap. Have a look at CRSI's design guide on pile caps. In short, you check different perimeters for different combinations of axial loads. For your case, I believe the full perimeter for all 4 columns will control.