Concrete thickness for slabs on grade subjected to uniform loading
Concrete thickness for slabs on grade subjected to uniform loading
(OP)
Hello,
What is the rationale for selecting the concrete thickness for a slab on grade subjected to uniform loading ?
The available literature ([1] and [2]) on slabs on grade design focuses on case studies where bending moments or punching shear on the slab are the driving factors, as is the case with lift truck traffic, concentrated loads (rack posts) or even uniform loads with an aisle, where significant negative bending moments may develop (think of warehouses).
In my particular case, I need to design the floor for water storage tanks where the loading is exclusively uniform. Assuming the underlying soil is uniform and stable (clays ruled out), how do I go about picking the concrete thickness ?
I understand this configures a very simple case (if not the simplest) as no flexural stresses are involved at all. Interestingly, [3] references [2] as the source for floor design, despite the fact that [2] doesn't cover slabs on grade subjected to uniform loads.
Thanks in advance.
References:
[1] "Designing Floor Slabs on Grade" by Boyd C. Ringo and Robert B. Anderson
[2] "ACI 360R-92 Design of Slabs on Grade"
[3] "Recommended Practice for Precast Prestressed Concrete Circular Storage Tanks" by the PCI Committee on Precast, Prestressed Concrete Storage Tanks.
What is the rationale for selecting the concrete thickness for a slab on grade subjected to uniform loading ?
The available literature ([1] and [2]) on slabs on grade design focuses on case studies where bending moments or punching shear on the slab are the driving factors, as is the case with lift truck traffic, concentrated loads (rack posts) or even uniform loads with an aisle, where significant negative bending moments may develop (think of warehouses).
In my particular case, I need to design the floor for water storage tanks where the loading is exclusively uniform. Assuming the underlying soil is uniform and stable (clays ruled out), how do I go about picking the concrete thickness ?
I understand this configures a very simple case (if not the simplest) as no flexural stresses are involved at all. Interestingly, [3] references [2] as the source for floor design, despite the fact that [2] doesn't cover slabs on grade subjected to uniform loads.
Thanks in advance.
References:
[1] "Designing Floor Slabs on Grade" by Boyd C. Ringo and Robert B. Anderson
[2] "ACI 360R-92 Design of Slabs on Grade"
[3] "Recommended Practice for Precast Prestressed Concrete Circular Storage Tanks" by the PCI Committee on Precast, Prestressed Concrete Storage Tanks.





RE: Concrete thickness for slabs on grade subjected to uniform loading
RE: Concrete thickness for slabs on grade subjected to uniform loading
The theory makes sense as you cannot 100% guarantee that the entire soil surface under the floor is of a uniform stable nature - Regardless of how well you spec it.
I will try and find the formula.
csd
RE: Concrete thickness for slabs on grade subjected to uniform loading
@ csd72: I will really appreciate if you can find the formula. Some corporate customers request us the calculations of the structures they purchase, and certainly we cannot say "Well, for the floor item, it is common practice to adopt a thickness of xxx inches..."
Having a formula to back us up will look more professional.
Thanks again.
RE: Concrete thickness for slabs on grade subjected to uniform loading
If you have perimeter walls, the top of the slab near the walls will go into tension.