Monolithic Footing Design

[adcFL]

Anyone knows a method to design a Monolithic Footing (wall footing)integrated to slab on grade for residential structural design.
Thanks
adcFL
Miami, FL

 

[FloridaPE]

ADC,

The monolithic footing, or turned down slab edge, is primarily a means of terminating the slab pour without have the masonry crew show up to lay two courses of block (in Florida where we have no frost line). This type of foundation can typically support a one-story residential structure with no problem. For larger structures, and multi-story homes, the soil bearing under the monolithic footing should not exceed the allowable bearing pressure recommend by the soils report. In absence of a soils report in hand, a preliminary design based on an allowable soil bearing of 2,000 psf would be reasonable.

It is important to note the the wall or column load has to be taken by the contact area under the monolithic footing and cannot be distributed to the slab on grade.

If the residence is more than one story, you may want to consider a masonry stem wall on a strip footing.

John Carter, Tampa

 

[JAE]

The document I used to use in Texas with expansive clays was:

"Design of Slab-on-Ground Foundations", August, 1981
Prepared for: Wire Reinforcement Institute, 7900 Westpark Drive, McLean, Virginia 22101 and for the Concrete Reinforcing Steel Institute, 180 North LaSalle Street, Chicago, Illinois 60601.

The method was developed by a Mr. Walter L. Snowden, PE in Austin, Texas. It is an empirical method. There may be an updated version out there somewhere. I would start with CRSI.

 

[UcfSE]

I typically design the thickened edge as an eccentric footing (usually the load is eccentric) with no contribution from the slab or tapered area from the bottom of the footing to the slab. I agree with what John stated above.

 

[adcFL]

Thanks to everyone, I got PDF Dcoument from Wire Reinforcement Institute, it's interesting but the foundation design is like a grade beam and I'd like to get a footing design with a geometry like a thickened edge slab.

Thanks to Jhon really good explanation, I did a design with a software that a friend gave me but i want to know how to do the calculations.


Thanks
ADC
Miami, Florida