Reinforced Concrete Raft Foundation Design 1

[damo74]

I'm designing a raft foundation for a house. I note on most rafts that edge beams are used. Is it possible to omit these? Could somebody explain to me the exact function of them?

 

[SperlingPE]

It depends on the type of raft, soils present, and/or frost depth.

The turned down edges of the foundation may just be to get below a shallow frost depth. The turned down edges may be required for a post tensioned slab to resist expansive soils. More information needed or contact someone with experience in the design this type of foundation (local structural engineer or geotechnical engineer).