## Thickness used in punching shear calculation

## Thickness used in punching shear calculation

(OP)

I have a suspended 7" slab which has a 2" cement mortar finish. My question is if I can use the entire depth when calculating my effective depth d. The center of the bottom reinforcement is 7/16" from the bottom. So, my question is if my d in the punching shear equations can be 9" - 7/16", or must I use only the slab thickness (7" - 7/16")? Thank you in advance.

## RE: Thickness used in punching shear calculation

## RE: Thickness used in punching shear calculation

## RE: Thickness used in punching shear calculation

I have another question.

There is also 1" steel plate which covers the entire slab. In determining the strength for punching shear, I'm trying to figure out how much the plate will distribute the wheel loads (a single large vehicle). I can completely ignore the plate and follow AASHTO to get an E value, but I don't believe this applies to shear calculations. I can't use the method for columns and base plates, because it uses the value halfway between the column and the edge of the base plate; in my case, the base plate covers the entire floor.

Any ideas?

## RE: Thickness used in punching shear calculation

As far as utilizing the plate for shear strength, I presume you would again need to ensure that the plate and slab are acting compositely. If there's an epoxy holding the plate down to the floor than I imagine you'd be fine to assume plate contributes. If not, then probably not.

## RE: Thickness used in punching shear calculation