Interaction between flat slab and pile-cap

[Marcel gadban]

Hello everyone,
Im designing a flat slab supported by piles, some of the foundations i have to take pile caps due to big loads in column.
The slab is casted alone after the finish of the pile caps cast, so its two casts one for piles caps and then the slab.

My question is about the interaction between the slab and the pile cap, since the pile cap acting like a support for the slab, should i consider designing punching shear between the slab and the corners of the pile cap, shear punching design the same as interaction between corner of a slab and concrete wall.
For example, slab thickness is 30 cm, pile caps for 4 piles diameter 80 cm, pile cap size 350x350 cm and a thickness of 120 cm.

Am i doing a correct thinking? I would like to hear your opinions on that.

Thank you,
Eng. Marcel Gadban.

 

[KootK]

I think that you're on the right track if that 3500 x 3500 cap is supported at the corners by piles. I would expect that to behave quite a bit like concrete walls with respect to punching shear.