Difference Between One Way and Two Way Slab

What is the RCC slab :

Slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs, bridges, and other types of structures. The slab may be supported by walls, by reinforced concrete beams usually cast monolithically with the slab, by structural steel beams, by columns, or by the ground.

Slabs are classified into two types:

1. One Way Slab
2. Two Way Slab

#1 ONE WAY SLAB:

One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction.The ratio of longer span (l) to shorter span (b) is greater than 2, considered as One way slab because this slab will bend in one direction i.e in the direction along its shorter span

Due to the huge difference in lengths, load is not transferred to the shorter beams. Main reinforcement is provided in shorter span and distribution reinforcement in longer span.

Example: Generally all the Cantilever slabs are one Way slab. Chajjas and verandahs are an practical example of one way slab.

2 TWO WAY SLAB:

Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. In two way slab, the ratio of longer span (l) to shorter span (b) is less than or equal to 2.

In two way slabs, load will be carried in both the directions. So, main reinforcement is provided in both direction for two way slabs.

The Hands on and Basic Differences between One way and Two way Slab is shown below :

S.No	One-way Slab	Two-way Slab
1	If L/b the ratio is greater than to 2 then it is considered a one-way slab.	If L/b the ratio is less than or equal to 2 then it is considered a two-way slab.
2	In one-way slab, the main reinforcement is provided in a short span and distribution reinforcement is provided in a long span.	In two-way slab, the main reinforcement is provided in both directions.
3	In one-way slab, the crank is provided in two directions.	In two-way slab, the crank is provided in four directions.
4	The one-way slab is supported by a beam on two opposite side only.	The two-way slab is supported by the beam on all four sides.
5	In one-way slab, the load is carried in one direction perpendicular to the supporting beam.	In two-way slab, the load is carried in both directions.
6	The deflected shape of the one-way slab is cylindrical.	Whereas the deflected shape of the two-way slab is a dish or saucer-like shape.
7	Chajja and Varandha are practical examples of one-way slab	Whereas two-way slabs are used in constructive floors of the Multistorey building.
8	While designing one-way slab we provide less steel hence the depth of the slab increases, as a result, the thickness of the one-way slab is more as compared to the two-way slab.	While designing two-way slab we provide more steel hence the depth of slab decreases, as a result, the thickness of two-way slab is less as compared to the one-way slab.
9	The one-way slab is economical up to a span of 3.6 meters.	Whereas the two-way slab is economical for the panel sizes up to 6m × 6m.
10	In one-way slab quantity of steel is less.	In two-way slab quantity of steel is more as compared to the one-way slab.
11	In one-way slab, bending is only in one direction i.e. in a shorter span.	In a two-way slab, bending is in both directions.