Difference Between Oneway and Twoway Slab
In reinforced concrete construction, the slab is an extensively used structural element forming floors and roofs. a concrete slab is the plane element having the depth D much smaller than its span and width. it may be supported by reinforced concrete beams, by masonry wall or directly by column. Difference between the oneway slab and twoway slabs are as follows :Oneway Slab
Slab supported only on two opposite sides by rigid supports carry the load by flexure in the direction perpendicular to the supports. The plane surface of a predominantly uniformly loaded slab deforms into a cylindrical surface in which curvature and hence bending moment develops only in one direction such slabs are called oneway slab.Twoway Slab
The rectangular slabs supported on two adjacent, three or four edges, and with the ratio of longer to shorter span less than two, which carry the load by flexure in two perpendicular directions are called twoway slabs.Difference Between Oneway and Twoway Slab
S.No

Oneway Slab

Twoway Slab

1

If L/b
the ratio is greater than or equal 2 or then it is considered a oneway slab.

If L/b the ratio is less than 2 then it is considered a twoway slab.

2

In
oneway slab, the main reinforcement is provided in short span and
distribution reinforcement is provided in a long span.

In
twoway slab, the main reinforcement is provided in both directions.

3

In
oneway slab, the crank is provided in two directions.

In
twoway slab, the crank is provided in four directions.

4

The
oneway slab is supported by a beam on two opposite side only.

The
twoway slab is supported by the beam on all four sides.

5

In
oneway slab, the load is carried in one direction perpendicular to the
supporting beam.

In
twoway slab, the load is carried in both directions.

6

The
deflected shape of the oneway slab is cylindrical.

Whereas
the deflected shape of the twoway slab is dish or saucerlike shape.

7

Chajja
and Varandha are practical examples of oneway slab

Whereas
twoway slabs are used in constructive floors of the Multistorey building.

8

While
designing oneway slab we provide less steel hence the depth of the slab
increases, as a result, the thickness of the oneway slab is more as compared
to the twoway slab.

While
designing twoway slab we provide more steel hence the depth of slab decreases, as a result, the thickness of twoway slab is less as compared to the twoway slab.

9

The
oneway slab is economical up to a span of 3.6 meters.

Whereas the twoway slab is economical for the panel sizes up to 6m × 6m.

10

In
oneway slab quantity of steel is less.

In
twoway slab quantity of steel is more as compared to the oneway slab.

11

In
oneway slab, bending is only in one direction i.e. in a shorter span.

In a
twoway slab, bending is in both directions.

In practices, the choice of the oneway slab and twoway slab for a particular structure will largely depend upon the
 Economy
 Buildability
 Loading condition and
 length of the span
Also, read How to calculate unit weight of steel bar
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