Suspended Concrete Floor Slab Specifications

Suspended concrete slabs are typically used in larger buildings.

Suspended concrete floors are found in industrial and apartment buildings, schools, hospitals and parking decks. Because concrete is weaker in tension than compression, specifications for floors of this type call for a careful balance of concrete volume and weight, along with properly-applied tension reinforcement in the form of rebar.

Concrete

Choosing the type of concrete is where the process begins. Concrete is available in different weights and strengths, and can be conditioned for resistance to a variety of adverse environmental conditions. These factors must be considered when choosing concrete for a suspended slab.

Service Loads

Data required in calculating the specifications of a suspended concrete floor slab include the weight of people, traffic, movable objects and the structure itself, in addition to the structure's dead load and live load.

Reinforcing Specifications

When the concrete type and service loads are known, the size of reinforcing bar is chosen. The size of these bars is restricted by the thickness of the concrete slab. Specifications for bar sizes are determined by the American Concrete Institute.

Layout

After the bars are chosen, the area of steel in square inches per square foot of concrete is calculated. This figure is then used to determine the spacing of the steel bars.

References

• "Reinforced Concrete Design"; George F. Limbrunner, PE and Abi O. Aghayere, PE; 2010