metal building foundation on expansive soil 4

[DoubleStud]

I am trying to understand this detail that was done by another engineer. The building has been built. Now we are trying to add foundation to support overhead crane. So the grade beam spans from drilled pier to drilled pier. They put void box below the grade beam to eliminate uplift from the expansive soil below it. My question is, what will that do if the slab next to it is tied/poured over the beam? Wouldn't the slab going to push up? I have never done one of these before but if I were to detail it, I would just pour the slab over (or ledge) the grade beam. This way the grade beam will prevent the slab at the perimeter from settling, but will not prevent it from an uplift.

I am trying to figure out how I should do the drilled pier cap for my overhead crane. How do I transition from existing slab to the pile cap? Do I want the transition to be free to slide? Add expansion joint? But on the other hand I dont want water to seep through the joint and make the soil swell. Thoughts?

 

[dik]

Insulation on the inside face of the grade beam at loading docks to keep the frost from moving into the building, and bottom steel in the SOG to resist flexural stresses...

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

-Dik

 

[dik]

I just realised it... I never put chamfers (or whatever they are called) between a beam and a slab, even if the slab is structural.

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

-Dik

 

[BAretired]

Does the beam really need to be 12" thick? I would have expected 8".

 

[emmgjld]

I have been watching this thread for several days, awaiting for definite information on the expansive soils:
What is the actual soil profile? How Expansive are the soils? What underlies the leveling sand?
I can picture some scenarios that the detail in question could work.
I know of many situations where the detail in question would be poor or even a disaster.
There is not enough information to provide the answer to the OP.

 

[DoubleStud]

here is some clips from the soil report:

 

[dik]

or maybe 10", depending on the reinforcing and crack control...

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

-Dik

 

[DoubleStud]

BAretired, is there something I need to do differently at the cold joint from pier to pile cap? Do I need to specify something to prevent the rebar crossing the cold joint from rusting?

 

[BAretired]

...is there something I need to do differently at the cold joint from pier to pile cap? Do I need to specify something to prevent the rebar crossing the cold joint from rusting?

If you believe that rusting of reinforcement is likely to occur at the cold joint, I suggest you provide 3" of concrete cover around the perimeter of the pile to a depth of 3" below top of top of pile; but no such provision was provided between the pile and grade beam in the detail of the original post.