One-Way Flat Plate Punching Shear

[RickyDawson]

Can anyone guide me to an example calculation for punching shear through a one-way flat plate slab?

The popular "direct design" method is well enough documented, but what about if the slab isn't 2-way and doesn't have more than 3 bays in either direction? Is there a documented way of going about such a calculation? All the examples I have seen say that if the flat plate doesn't meet the requirements for using the Direct Design Method then more stringent analysis must be used - However, in all my searches I have never seen an example.

Is the calculation exactly the same as punching shear through a pad footing, except that the shear force is multiplied by certain factors to account for moment transfer from slab to columns?

Right now I am being forced to use the British method (which seems quite simple enough), only that I cannot justify it by anything I have found within ACI or CRSI.

Can anyone help? Thank you kindly.

 

[bookowski]

The punching shear is laid out in 11.12.6 for 318-05. That's not tied to the direct design, or any other, method.

You're right that you have to account for moment transfer but it's not by putting factors on the shear - look at 11.12.6.2 and the commentary for that section. You can probably find a worked example in a concrete textbook.

 

[UcfSE]

PCA Notes on ACI 318 has good examples and information for punching shear.

 

[rapt]

Direct Design method is a way of guessing the moments/shears/reactions in a building member. Personally I would never use it for design, only prelims.

In your university days surely you were taught methods of analysis that will allow you to calculate more accurately the actual moments/shears/reactions in the member you are designing.

Punching shear calculations then check the effects of these actions on the member you are designing.