Definition of a Floating Slab"

[ajk1]

What is the definition of a "floating slab"? Is it a slab that is supported throughout by soil ( versus a "suspended slab" that is reinforced to span between supports such as driled concrete piers founded on natural undisturbed soil of sufficient strength to support the load.

 

[Yao1989]

I usually understood floating slab as something that is not supported on foundation below frost, so it moves up and down with upheaving. Commonly used for small standalone garage & landscape slabs.

 

[WARose]

I've heard that definition as well. The whole "floating" thing also gets used with the so-called "raft" foundation. And the term is not used there with regards to how it is connected to anything (or frost).

 

[HTURKAK]

I think the definition ( floating slab ) is self explanatory.. If the slab supported directly on grade and does not have any connection or extra support from the foundation walls, structure etc.. called floating slab..

Just write floating slab and search the web, one of the possible outcomes;

 

[ajk1]

In otherwords, a floating slab seems to be what I used to in my younger pre-retirement days decades ago, call a slab-on-grade or slab-on-earth. Right?

 

[X4vier]

In Colombia, a floating slab o floating foundation is one in which the basement or the under-earth levels compensate the weight of the whole building with the weight of the earth removed.
Theoretically, under those conditions, the bearing soil will be exactly at the same pressure that before constructing the building.

 

[BAretired]

I have always understood a floating slab to be one which is supported by soil.

BA

 

[MotorCity]

It is an architect's dream......a floor supported without columns.

 

[WARose]

In Colombia, a floating slab o floating foundation is one in which the basement or the under-earth levels compensate the weight of the whole building with the weight of the earth removed.
Theoretically, under those conditions, the bearing soil will be exactly at the same pressure that before constructing the building.

Technically that is correct. I've seen the terms used interchangeably everywhere. Even in texts. Gupta (in his book: 'Raft Foundation Design And Analysis With A Practical Approach', p.6-7) refers to the situation as a "buoyancy raft".

Coduto (in 'Foundation Design Principals and Practices', 2nd edition, p.647) provides this historical perspective:

"The earliest documented floating foundation was for the Albion Mill, which was built on a soft soil in London around 1780. It had about 50 percent flotation (i.e. the excavation reduced Δσ'[sub]z[/sub] by 50 percent) and, according to Farley (1827), "the whole building would have floated upon it, as a ship floats in water." In spite of this pioneering effort, floating foundations did not become common until the early twentieth century. Early examples include the Empress Hotel in Victoria, British Columbia, 1912; the Ohio Bell Telephone Company Building in Cleveland, 1925; and the Albany Telephone Building in Albany, New York, 1929."

 

[ajk1]

Thank you everyone. Interesting answers. I have not been on this system for quite some time, so it is great to see the names that I used to see, like BARetired who I recall generally held similaar thoughts as I, and I recall kindly defended me when someone sought to mock. Stay well everyone.

 

[BAretired]

You stay well too, ajk1.

BA