Punching Shear Critical Perimeter EN 1992-1 version 2015 VS 2021

[soleilmr]

Hi All,
I am calculation punching shear for foundation slab. I am getting quite diffent values if I calculated based on the 2021 vs 2015 code edition. In thh new code they take shear stress at 0,5d distance from the support, whereas in the old code the critical perimeter that varies from 1d to 2d.
Another difference I noticed is the term 2d/a, which gives a 4x difference for a 0,5d distance.

Basically I am trying to see if I understand the requirement of 2021 code correctly or why is there such a change?!

https://files.engineering.com/getfi...ae0-9687-02e09b41316a&file=EN_1992-1_2021.PNG

https://files.engineering.com/getfi...91-40d6-a332-368d17d23f2c&file=2021vs2015.PNG

Thanks for your input!

 

[rapt]

The old method was based on Zustti's logic and the perimeter was set at the larger distance to match the method to test results.

The new code uses The Critical Shear Crack Theory developed by Muttoni and has gone back to using .5d for the perimeter, along with limitations on the length of the perimeter on each face to allow for corner concentrations.

The whole logic is completely different. There is no logic to compare individual terms in the 2 methods.

 

[soleilmr]

@rapt
Thank you! That is exactly the info I was looking for, to understand why there is such a change.