## Concrete Slab Design

### Flexure Design: One-Way Slab

The procedure for designing a one-way slab in flexure is the exact procedure used to design a concrete beam. Assume a tributary width of 1' and find the necessary steel required (A_{sr}). then find the necessary spacing of the steel by:

s = {A_b\over{A_{sr}}} (12 in)

*where:*

s = the spacing of the rebar

A

A

_{b}= the area of an individual rebar### Maximum spacing for the main steel ^{[1]}:

s_{max} for slabs in flexure is the smallest of:

- 3 times the slab thickness (not depth)
- 18"

### Differences in design procedures between a slab and beam:

Although the calculations to find A_{sr} for a beam and slab are the same, some differences between the two design procedures do exist. Those differences are:

- The min. cover for the steel is 3/4".
- The minimum steel ratio is bound by the temperature and shrinkage steel. Therefore the minimum steel for beam design does not apply.

### References

- American Concrete Institute, "ACI 318", 2005
- Found in section ACI 318.7.6.5