Requirements of Drop panel in flat slab 1

[bdlc2k]

ACI states that a drop panel dimension should be L/6 in both directions. Is this required if the drop panel is being considered for punching only, not for flexural design (say when a two way slab has shearwalls)? Has anyone ever taken this approach?

 

[M.Abdelmonem]

My understanding is this dimension recommendation is for punching where the concrete dimensions for depth and plan dimensions could be considered, on the other hand if the drop panel is used for flexure design you are already choose the slab appropriate thick to safe your design and to choose the reasonable steel ration for the slab as well as to safe the other serviceability of the slab, already this case is judgmental issue according to the resulted slab stiffness.

 

[KootK]

I don't think I've ever seen drop panels approaching twice the slab thickness.

2x seems to be pretty much the standard in the western provinces, both for the logic that rapt mentioned and as a result of Per's influence.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[dik]

KootK... rapt and I were on the same page roughly... he was including the slab thickness in the drop thickness and I was excluding it... They had the old plastic model that Per used in the Toronto office for years; I don't know if they took it with them when they changed offices.

Dik

 

[rapt]

Dik,

OK, I think we all interpreted

"Rapt... we're talking the same thing."

to mean that we were both talking total depth. Whereas you actually meant that you were suggesting a drop depth below the slab equal to the slab depth, so total depth = 2 * slab depth.

 

[Settingsun]

I interpreted Dik's response the same way as Rapt did. Not the first time I've found engineers having trouble communicating to other engineers on this forum. I wonder what misunderstandings our non-engineer clients think we are telling them...

 

[rapt]

Steveh49,

And we all have English as our 1st language. Imagine how it is for someone for whom English is a 2nd or 3rd language.