Designing a two way slab 1

[petrosoft]

Does anyone have a good reference or software package for designing a two way or one way slab. It's for a residential slab on pier/grade beam with weak soil conditions.

Thanks--Peter

 

[asixth]

A good reference for the design of two-way slabs includes Nilson's "Design of Concrete Structures". This textbook should give you a good understanding of the theory behind the design of reinforced concrete slabs and some of the design aspects to ACI318.

For your situation, I would design the slab to span between piers. I would be mindful of punching shear around the pier/slab connection as well as any reverse loading that may result from soil swelling.

I'm not sure on which code you are designing to but it may be useful to search for some residential footings guidelines for your region.

 

[petrosoft]

Thanks for that suggestion of using piers without grade beams. In this situation, grade beams are essentially thickened slabs and are easy to form. Isn't the steel detailing simpler for slabs on grade beams as opposed to slabs on piers by themselves?

I'm in California,USA.

 

[asixth]

How's the weather in California?

I wouldn't disreguard the grade beams altogether, I would assume in the worst case scenario that you have lost the bearing underneath your slab and thickening and I would design the loads to span between piers.

What is the size of this residence you are designing, one-family home, townhouse, apartments?

I'm on the other side of the world and our residential guideline for footings on reactive soils recommends a 12" x 16" grade beam with 3-No.5 bars bottom, 4" thick slab reinforced with No.3 bars at 8" both ways.

Without knowing what loading you are designing for, I would do an independent number on this.

Keep your thickenings at 12' centres and the design should be fine.