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What is Differences between One Way Slab and Two Way Slab

Differences between One Way Slab and Two Way Slab

In this Article we will discuss about Differences between One Way Slab and Two Way Slab But Most Civil Engineers students gets confused when asked about the questions related about the differences between one way slab and 2 way slab. If u want to know about their differences, this article we will explains it in detail with definitions & comparison chart.

Differences between One Way Slab & Two Way Slab

Slab

Slab is the horizontal member of structure the top & bottom surfaces of  the slab is parallel to each other. The depth of the slab is very small compared to its span. slab is constructed on top of the walls, beam or column of the structure. In multi-story building in the top slab is called roof slab and the lower slab are called floor slab. Slab may be constructed from different material such as steel, concrete, bricks etc. it creates flat horizontal surfaces like floors, roof decks & ceilings. Usually the depth of the slab is slightly thick & supported by beams, columns, walls, or the ground.

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Slabs are classified into 2 types.

  1. One Way Slab

  2. Two Way Slab

One Way Slab

According to the IS 456:2000 the slab in which the ratio between longer span ( L ) & shorter Span (B) is equal or greater than 2 is called  1 way slab. In case of 1 way slab the load is the carried in 1 direction and on that direction main bars are designed and on other direction thin bars are used compered to the main bars which are called distribution bars.

One way slab = Longer span / shorter span > 2

Differences between One Way Slab and Two Way Slab

Two Way Slab

The Slab in the ratio between the longer span ( L ) and the shorter span ( B ) is less than two is called 2 way slabs. In case of 2 way slab loads are the distributed in both direction & it is supported from all the sides which is why the load can be distributed on two direction in square shape area the main bars can be used on either side.

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but the main bars will always beneath the distribution bars but if the shape of the area is in rectangular shape then the main bars should be used in shorter direction and distribution bars should be used in the longer direction.

Two way slab = Longer span / shorter span < 2

2 way slab

The difference between One Way Slab And Two Way Slab are shown in the table which is the given below.

S. No

One Way Slab

Two Way Slab

1

The length of  longer span is 2 times equal or greater than the length of the shorter span.

The length of  longer span is equal or less than 2 times length of shorter span.

2

In IS code 456:2000, The ratio of the longer span ( L ) to shorter span ( b ) which is ( L / B) greater than two is known as 1 way slab.

In 2 way slab, the ratio of longer span to shorter span is less than two.

3

Based on the deflection & Considering the span the thickness of slab may vary from four inch to Six inch( 100-mm to 150-mm ).

Based on the deflection & considering the span the thickness of the slab may vary from Four inch to Eight inch ( 100-mm to 200-mm )

4

1 way slab is reinforced by beams on the Two shortest sides to transmit the load along one direction.

2 way slab is reinforced by beams on all the Four sides and the loads are transmitted by the supports along both directions,

5

1 way slab curves, deflect or bend in a direction vertical to the supporting ends.

2 way slab curves, deflect or bend in the both directions.

6

Bent shape of 1 way slab is cylindrical.

Bent shape of 2 way slab is dish-shaped.

7

1 way slab has strength in shortest direction.  

2 way slab has strength in both direction. These types of slabs are mostly used in the floor of the multistory buildings.

8

Main RCC is provided on shorter direction due to bending.

Main RCC is provided in both directions due to bending happens on both sides.

9

1 way slab is economical as compared to 2 way slab.

It’s more expensive compared to 1 way slab because steel bars are used more in it.

10

In 1 way slab the load is carried on one direction.

In 2 way slab the load is carried  on the both direction.

11

Beams  supported the 1 way slabs on two sides.

Beams  supported the 2 way slabs on four sides

12

Mostly the shape of 1 way slab is rectangular.

Mostly the shape of 2 way slab is square.

13

The design of 1 way slab is totally different from 2 way slab.

Design of 2 way slab there equations, steps of methods everything is different from 1 way slab.

14

In 1 way slab the extra bar or crank bar are provided on one direction or on the 2 sides.

In 2 way slab the extra bar or crank bar are provided on both direction or on four sides.

15

The Deflection of the 1 way slab looks like cylindrical.

The deflection of the 2 way slab looks like bowl.

Conclusion

The main objective of this article “What is the Differences between 1 Way Slab and 2 Way Slab” is that the ratio between longer span to shorter span will be greater than 2 in 1 way slab & carried the load on only 1 direction while in 2 way slab the ratio between longer span to shorter span will be less than ( 2 ) &  carried the load on both direction.


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