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Punching shear with unbalanced moment with two drop beams

Punching shear with unbalanced moment with two drop beams

Punching shear with unbalanced moment with two drop beams

(OP)
Hi everyone...this is my first post in this forums, its a pleasure to be withing a people that are very intelligent and experienced.

I have a punching problem, the geometry as shown:


To consider the effect of the loads and the connected beams (400x600mm), i used the software to find the maximum stress and its shown as follow:


I neglected the effect of the beams and calculate the perimeter as its internal column, the question is:

To compare with the allowable stress (which is 2.1 mpa) should i take the average for all 4 sides or consider the highly stress side.

Thanks

RE: Punching shear with unbalanced moment with two drop beams

Using my code, punching shear perimiter for shear wall (with moment on base) would be critical at the more stresed side.
In the longitudinal direction perimiter would span cca 1.5*thicknessofwall
I suggest you browse your concrete code

RE: Punching shear with unbalanced moment with two drop beams

1) I would take advantage of the shear carrying capacity of your beams. Beam shear is a more reliable mechanism than punching shear.

2) With most concrete codes, it is not appropriate to compare FEM punching stresses to allowables. Rather, one is to take the aggregated shear and bending forces output by FEM and post-process approximate stresses using simplified P/A + M/Sx type methods. Punching shear provisions are research based and calibrated to such methods.

3) Agree with Kiltor regarding the appropriateness of specific wall end punching checks. My country's code doesn't give specific guidance unfortunately.

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 with unbalanced moment with two drop beams

(OP)
Thanks Klitor and Kootk for your helpful responses....

- Regarding the carrying capacity of the beams they are already accounted for by the FEM analysis.
- I thought using the FEM analysis will give similar result as they are pure shear stress, I will verify this soon by comparing with manual calculation.

Thanks again

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