Learn about the Difference the Main Bar and Distribution Bar

Two sizes of bars are used in slab for any reinforcement detailing. The two are the main reinforcement bars and the distribution bars. You will learn the difference between main reinforcement bar and distribution bar in this article.

The bending moment of a slab is when a load is applied to a slab, a positive moment will be experienced by the bottom of the slab and with this the support will experience a negative moment. A high tension will be experienced by the bottom and the top of the slab at the same time.

There will be a high deflection in short span and a low deflection in longer span.

Function of Main Reinforcement Bars

In a shorter span direction, the main reinforcement bars will be provided so as to transfer the bending moment that is developed at the bottom of the slab. To transfer the bending load main bar is provided which develops at the bottom of the slab to the beams.

1. At the bottom of the slab in the shorter direction the main reinforcement bar is provided.

2. As main bar stronger dimension bar is used.

In one way slab the main reinforcement bar is provided and the slab is supported by beams on two opposite sides. Whereas, in two-way slab, on all four sides beams are present to support the slab. Therefore, there will be no difference in bar size as each of the sides will have to transfer load evenly.

Function of Distribution Bars

1. To resist shear stress distribution bars are provided, in longer span cracks starts developing.

2. Perpendicular with the top of the main bar distribution bars are provided.

3. Lesser dimension bars are used.

4. In the longer span direction distribution bars are provided.

Difference between Main Bars and Distribution Bars

1. Usually, the main reinforcement bars are placed at the bottom of the slab. On top of the main bar distribution bars are placed.

2. In shorter direction main bar is used whereas in longer span distribution bar is used.

3. As main reinforcement bar higher dimension bar is used. As distribution bar lower dimension bar is used.

4. To transfer the bending moment to beams main reinforcement is used.

To reduce shear stress distribution bars are used and the cracks develop at the top of the slab.

Video Source: Civil Engineering