Punching shear on plain concrete pad foundation Eurocode 2

[TWfea]

I have been asked to design a "temporary pad foundation", for 4 support towers used to support some formwork. Due to the temporary nature, their preference is for plain concrete.
My issue is that there doesn't seem to be a straight forward way to implement the Eurocode 2, for punching shear on plain concrete. Based on the shear calculations for plain concrete (12.6.3) I've made (t_cp /fcvd ~ 0.1), I don't expect that there will be any issues. However for the sake of completeness I would very much like to include these calculations.

Section 12, in the Eurocode 2 covers plain and lightly reinforced concrete structures, but there is no direct mention of punching shear.

Can I apply the formula for Vrdc, and Vrdc,max as I would if the foundation had tensile reinforcement?

I would be very grateful if someone point me in the right direction to enable me to calculate punching shear according to the Eurocode 2 at 0d, and 2d from the column face.

 

[EireChch]

Not sure if you are planning to leave it unreinforced, but for the minuscule cost of a sheet of A393 mesh top and bottom, just stick it in.

 

[HTURKAK]

Pls look Clause 6.4.4 . The shear strength of concrete varies with longitudinal reinf. You are expected to use the expression (6.47) . In your case , ρl is zero and Vrdc min = 0.035( k^1.5)*( fck)^0.5.

 

[TWfea]

Thanks HTURKAK, I implemented the formula from clause 6.4.7, and the design passes all the checks

We are still considering putting in the minimum steel reinforcement. Although the foundation strength is more than adequate, the addition of reinforcement will only be to err on the side of caution!

Thanks again for all your help!

@EireChch, thanks for you input it surely is a minimum cost for piece of mind!