Main Bar and Distribution Bar in Slab

The bars with two different sizes are mainly applied in the slab for any reinforcement which range from main reinforcement bars and distribution bars.

But there are some basic differences among the main bar and distribution bar which are described below :-

To get more clear ideas, gather information on the bending moment on slab.

If there is any load on a slab the bottom of the slab undergoes positive moment (Sagging) and the supports undergo negative moments (Hogging). The bottom part together with the top part of the slab, will undergo extreme tension simultaneously.

The deflection becomes extremely very high in shorter period and low in longer period. High amount of tension will prevail in the support which is near than the other one.

Purpose Of Main reinforcement bars:

Main reinforcement bar is placed at the shorter span direction with the purpose of transforming the bending moment that is formed at the bottom of the slab. The prime objective of arranging main bar is to transmit the bending load to the beams.

1. Main reinforcement bar is placed at the bottom of the slab at the shorter direction.

2. Stronger dimension bar is utilized as main bar.

In one way slab, the beams provide support to the slab on the two opposite sides where main reinforcement bar is placed.

In two way slab, the beams provide support to the slab on all four sides. The size of the bar will be unchanged since each side has to transmit equal amount of stress uniformly.

Also Read: Importance of providing crank bars in slabs and beams

Function Of Distribution Bars:

1. The purpose of distribution bars is to defy the shear stress, cracks produced in the longer span.

2. Distribution bars are placed perpendicularly with the top of the main bar.

3. The bars with lesser dimension are provided.

4. Distribution bars are provided in the longer span direction.

Variation Among Main Bars And Distribution Bars:

1. Main reinforcement bar is generally applied at the bottom of the slab.

2. Distribution bars are provided on the top of the main bar.

3. Main bar is applied in shorter direction whereas distribution bar is applied in longer span.

4. Higher dimension bar acts as main reinforcement bar.

5. Lower dimension bar should be utilized as distribution bars.

6. Main reinforcement bar is applied to transmit the bending moment to beams.

7. The purpose of distribution bars is to withstand the shear stress, and cracks produced at the top of the slab.