Slab-on-Ground

[StructuralAddict]

Section 1.4.7 of ACI 318-14 states the following "This Code does not apply to design and construction of slabs-on-ground, unless the slab transmits vertical loads or lateral forces from other portions of the structure to the soil."

Could someone please explain to me what is meant by vertical loads? And what are some examples of a slab that does not transmit vertical loads? Like what is the purpose of the slab if it doesn't transmit load to the soil?

 

[phamENG]

Transfer loads. So if you have a load bearing wall sitting on the slab, it's transferring those loads. It's not "transferring" occupancy loads in the room where it serves as a floor.

 

[StructuralAddict]

Thank you; so the occupancy load directly supported on the slab on grade (like people, furniture, non-bearing walls, partitions, fixtures) are not considered as "vertical loads" to be transmitted by the slab. As such, the Code does not apply to the design and construction of such a slab on grade. I hope my understanding is correct now.

 

[phamENG]

Essentially, yes. This applies only when the soil is capable of providing continuous support to the slab. The slab is then proportioned so there is really no significant bending stress in the slab.

If the soils are not suitable for this, and the slab must bridge over bad soil, then you have a structural slab and it should be designed per ACI 318.

 

[phamENG]

Take a look at ACI 360