drop panel vs pier cap

[oengineer]

I am just looking for clarification between a drop panel and pier cap for foundations. New to building design industry and I am familiar with pier caps but not drop panels.

 

[WARose]

A drop panel is a thickening of a slab around a column.....typically done with a two-way slab system for shear. And this is at multiple levels.

A pier/pile cap is the concrete that transfers the supporting structure loads into the piles.

 

[KootK]

I may disagree with WARose somewhat, we'll see. Speaking to the case of elevated slabs:

1) The primary motivation for column capitals is to improve punching shear. Capitals are generally small in plan.

2) The primary motivation for drop panels is to improve flexure and deflection. Drop panels are relatively long in plan, perhaps 1/3 of the slab span.

Are we talking in reference to elevated slabs here or, truly, about foundations?

 

[KootK]

Most any kind of underside slab thickening located at a pile in a mat foundation will be an attempt to address shear as WARose said. I see that yo have some other threads in progress at the moment regarding raft foundation slabs so I'm guessing that's what we're dealing with here. For foundations, my opinion is that a pile/per cap is simply the medium between piles supported vertical structure that allows for load distribution and tolerance accommodation.

 

[oengineer]

@KootK: Are you using pier capital and pier cap interchangeably? I am not familiar with the term "pier capital".

Also, this is in reference to a slab on grade foundation.

 

[jayrod12]

If it's slab on grade, there should be no requirement for drop panels or pier caps.

If it's a structural slab at grade, where you will have voidform below, then you may need drop panels.

Drop panels as WARose and Koot indicated are a relatively large thickening of a slab to improve specific performance of a structurally supported slab, not a grade supported slab.

A pier cap is a concrete piece poured on top of the pier to dial in bearing elevations etc.

A column capital is a localized widening of a column at the underside of slab to improve punching shear resistance.