__One-Way Slab__
As per is
456-2000, in case of one-way slab the ratio of longer span to shorter span is
equal or greater than 2.

That is –
L/W ≥ 2

**Example:**

Consider
is a slab of 8m X 3m

(8m is the longer span & 3m
is the shorter span).

So, 7m /
3m = 2.666m

؞ 2.666m ˃
2

This is called a one-way slab.

**Bending Moment:**

In the case of a one-way slab,
the slab bends in only one direction. That is in the direction along its
shorter span.

**Deflected Shape:**

The deflected shape of a one-way
slab is cylindrical.

**Support:**

In a one-way slab, the slab is
supported by the beams on two opposite sides.

Example: Chajja, Veranda

**Load Carrying Direction:**

In one way slab the loads are
carried along one direction.

**Reinforcement:**

In a one-way slab, slab bends in
one direction. And it’s to counter on the bending in main steel, cranked bar or
extra bar are provided in the shorter direction.

**Slab Thickness:**

When designing a one-way slab, we
provided less steel. Hence the depth of slab increases. As a result, the
thickness of the one-way slab is more as compact as a two-way slab.

**Use:**

The one-way slab can be
economical up to a span of 3.6m.

__Two-Way Slab__
As per IS
456-2000, in the case of the two-way slab the ratio of longer span to shorter
span is less than 2.

That is - L/W < 2

**Example:**

Consider is a slab of 5m X 5m

(5m is the longer span & 5m
is the shorter span).

So, 5m / 5m = 1.0m

؞ 1.0m <
2

This is
called a two-way slab.

**Bending Moment:**

In the case of a two-way slab,
the slab bends in both directions.

**Deflected Shape:**

The deflected shape of the
two-way slab is a dish.

**Support:**

In a two-way slab, the slab is
supported by the beams on all four sides.

Example: The two-way slab is used in the floor of a multi-story
building.

**Load Carrying Direction:**

In two way slab the loads are
carried along with both directions.

**Reinforcement:**

In a two-way slab, slab bends in
both directions. And the main steel cranked bar or extra bar is provided on
both directions to counter this bending.

**Slab Thickness:**

When designing a two-way slab, we
provided more steel. Hence the depth of slab decreases. As a result, the
thickness of the two-way slab is less as compact to a two-way slab.

**Use:**

The two-way slab can be economical
for the panel sizes up to 6m X 6m.

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