Slab On Grade Capacity

[Ryan H]

Hello,
I have a 10" slab on grade with #4 @ 12" o.c. top each way and bottom each way.
I have an unknown K factor for the slab and it is spec'd as 4000 psi concrete

Can anyone please provide the equation to calculate the PSF capacity of the slab?

 

[ATSE]

You need to provide (a lot) more information. Not a simple answer.
Subgrade (soil) properties, joint type, edge type, loading condition, dimensions... all matter.
Also, are you ignoring reinforcing (as the PCA method does), or is reinforcing active? Reinforcing crossing joints?

 

[DaveAtkins]

The best way to analyze this is to perform a finite element analysis, using a computer program (I use RISA-3D). You make an assumption about the soil springs below the slab, and try different patterns of loads to determine what the maximum moment and shear in the slab will be.

So...there are too many variables for any of us to give you a quick answer.

That being said, in my experience a 10" slab should be OK for at least 250 psf uniform load. Highway slabs are generally 9" thick, and are not reinforced.

DaveAtkins

 

[Ryan H]

yes sorry
reinforcing is across joints and I assumed active.
subgrade materials are unknown because I do not have a soils report at this time, i'd like to assume average / below average as the site appears standard
slab is inside a large 100'x65' building which will see municipal parking vehicles (30 tons

control joints max 225 ft^2 area
perimeter is bearing ledge on either foundation wall or footing

 

[dik]

I don't know if they still have it, but PCA used to have an airport pavement program... originally for DOS then modded for Windows. It was excellent and I used if for numerous SOGs, pavements and runways.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

FYI

http://www.ce.memphis.edu/4155/Powerpoints/23 - PCA Method.pdf

and

https://www.acpa.org/airpave/

30 day trial. I don't know how good the new version is, but the old one was one of the better programs in my stable. Used it for everything from 747s to warehouse racking. It was extremely useful. $300 license (cheap IMHO) if as good. I think my old copy from 20+ years back was just under $200. Your loads aren't overly high for a 10" slab on good base... but, you really need the modulus of subgrade reaction... has a huge bearing on the outcome. It was based on elastic solution by Packard... I used to have the source code for his solution... it's likely down in a box somewhere...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Denial]

On my website (

http://rmniall.com)

there are two spreadsheets that calculate moments and deflections (but not shears) for infinite and semi-infinite slabs on an elastic ("Winkler") foundation.[ ] They might be useful for some preliminary investigations, before you wade into the FE work.

 

[Ryan H]

Denial,
I am on your site, can you provide me an additional link to the spreadsheets? I see various spreadsheets but none that pertain to S.O.G.

 

[STrctPono]

Try FAARFIELD. Link

 

[Denial]

Ryan,
Fully infinite:

http://rmniall.com/downloads/software-downloads/#ISOEF

Semi-infinite:

http://rmniall.com/downloads/software-downloads/#ESOEF