Slab on grade design 4

[gbirth8]

Hello all,

New engineer here with minimal RC design experience, but I am trying to self teach and stumbled upon this site that seems to have a nice group of intelligent people.

The career path i am on currently will see a lot of design for Ag purposes (manure pits, heavy use areas, etc.)

The first one i am starting simple with a heavy use area (slab on grade), should the As be calculated treating it as a one way? I would assume to be safe for farm equipment and dairy cows that a 10KPA load is more than sufficient plus the wright of the slab itself. Calculate the moment, in turn get your As, can then get your joint spacing using the subgrade drag equation.

The slab would also have about a 3' high wall (concrete) around the perimeter to contain the poo so stormwater does not have to be collected and treated. Also allows for a skid steer or some kind of tractor to clean up the poo

am i on the right path here? Im normally just a site civil guy, trying to expand my knowledge and capabilities

Thanks

 

[JLNJ]

Pavement/slabs are grade normally designed as unreinforced elements on a compressible subgrade. There are a myriad of design guides for this type of design. The self-weight of the slab is normally ignored. Most design guides take into account two-way action; however, the design near joints and corners often controls. I don't see too many references to "one-way" action for a slab on grade.

If you have a retaining wall along the perimeter, then it would be a reinforced concrete element. Depending on the size of the area, you might want to run at least some reinforcement though the entire slab, maximizing your joint spacing. Frost penetration might also be a concern for you.

 

[dik]

Some info... it's a work in progress, but has some info.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1670609231/tips/Slab_on_Grade_22-05-31_dlylai.pdf[/url]

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[AgMechEngr]

I am guessing this is for a loafing shed. Ditto to reinforcement. You will also need to specify the finish to prevent injury and hoof wear. Parallel grooves 0.5" deep by 0.5" wide spaced 3-4 inches apart on center is common. This can be done after curing.

Seal your joints to prevent freeze-thaw damage.

 

[fel3]

Here are a few more resources, pulled out of the References section of my Mathcad worksheet for designing slabs on grade used for vehicular traffic:
[ul]
[li]American Concrete Institute, "ACI 360R-10, Guide to Design of Slabs-on-Ground," April 2010.[/li]
[li]Portland Cement Association, "Slab Thickness Design for Industrial Concrete Floors on Grade," 1996.[/li]
[li]Departments of the Army and Air Force, "Army TM 5-809-12/Air Force AFM 88-36, Chap. 15, Concrete Floor Slabs on Grade Subjected to Heavy Loads," August 1987.[/li]
[/ul]

I generally follow ACI-360R and I pay attention to advice in the other two documents.

============
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[gbirth8]

Pretty much AgMechEngr,

It is more of a "play area" if you will as it is a organic dairy farm, the cows have to be "outside" for so long everyday. There are arguments on whether or not it being covered constitutes it as being outside, but that is an argument between him and his organic milk inspector.

As of now I have the reinforcement as a mat of #4 spaced 16"OC, assuming a load of 210 psf and joints spaced 15' (went with 30*thickness slab)

All joints for sure get sealed up here, freeze thaw is very prevalent in the north country of NY

 

[dik]

Time of sawcutting is critical... at most 6 to 8 hours after finishing... with a sofcut type saw this can be reduced to a few hours. If it's not done right, it doesn't matter what your spacing is... the slab will determine where the shrinkage cracks will occur.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Aesur]

The book "Designing Floor Slabs on Grade, Step-by-Step procedures, sample solutions and commentary" by Boyd C Ringo and Robert B Anderson is an amazing book about slabs on grade design. It's expensive, but worth it.