What Is Slab?

Function of Slab

1. The slab provides a platform to work on the structure.
2. The one-way slab or two-way slab method is properly used to transfer the load on the slab.
3. The slab provides a flat surface to work with easily.
4. The design of the multi-story building has been made possible by slabs.
5. The slab can be used as a sound, heat as well as a fire insulator.
6. The slab helps to keep the room private.

Type of Slabs

• One Way Slab
• Two Way Slab
• Flat Slab Resting Direction on a Column Without Beam
• Grid Slabs or Waffle Slab

1. One-Way Slab

1. The supported slab on each of the two walls is always supported by one slab.
2. A slab supported by less than four sides in a slab Structure in a building can be designed as a one-way slab.
3. All cantilever slabs are simple examples of a one-way slabs.

2. Two Way Slab

3. Flat Slab

1. The flat slab can be properly planned for partition walls.
2. Using a flat slab for a building can give the owner the opportunity to choose a room layout as needed.
3. Using a flat slab in a building eliminates the need for false ceilings.
4. The floor height can be increased as no beams are used in the flat slab.

4. Grid Slab

Analysis of Slab

1. Elastic Analysis

2. Code Coefficients:

3. Yield Line Theory

Reinforcement Details In Slab

1. One Way Slab Reinforcement Details

• In a one-way slab, the load is transferred from one side to the other. In this type of slab, the maximum load will be transmitted over a long span. Therefore it is necessary to give proper reinforcement on the long-span side.
• So in a one-way slab to provide adequate support to the long-span side, the main reinforcement is placed parallel to the short span by proper spacing, and the distribution reinforcement is placed on the long side according to the correct spacing.
• Therefore, one-way slabs are preferred over the short span of the slab. Where main reinforcement is given on long-span due to bending. Reinforcement of one Way Slab is given as shown in the figure.

2. Two Way Slab Reinforcement Details

• In a two-way slab, the applied external load is transferred to both sides in a long span and short span.
• In two way slab, the main reinforcement is laid on both sides. In this type of slab, the load on both sides is evenly distributed.
• In RCC two Way slab, each of the four sides is held on the beam by main reinforcement. A load of a two-way slab is transferred through structural elements such as beams.

Types of Loads Acting on Slab

• Wind load
• Live load
• The dead load of the slab
• Earthquake loads
• Snow load

Difference Between One Way Slab and Two Way Slab

1. One Way Slab Vs Two Way Slab: Definition

• In a one-way slab, the length of the long span is greater than the ratio of the short span to two.
• In a two-way slab, the length of the long span is less than or equal to the ratio of the short span.

2. One Way Slab Vs Two Way Slab: Support

• One-way slab Only two opposite sides are supported by a beam or wall.
• The two-way slab is supported from all four sides.

3. One Way Slab Vs Two Way Slab: Transfer load

• One Way Slab, the utmost load is transmitted by long span.
• In Two Way, Slab load is transferred in both spans (long span and short span).

4. One Way Slab Vs Two Way Slab: Require Reinforcement

• A one-way slab requires less reinforcement than a two-way slab.
• Two-way slabs require more reinforcement than one-way slabs.

5. One Way Slab Vs Two Way Slab: Bending Moment

• In one way slab, a bending moment occurs in a short span in only one direction one-way slab, a bending moment occurs in a short span in only one direction.
• The bending moment in a two-way slab occurs in both directions, a longer span and a shorter span.

6. One Way Slab Vs Two Way Slab: Shape

• The shape of a one-way slab is usually rectangular.
• The shape of a two-way slab is usually square.

7. One Way Slab Vs Two Way Slab: Direction of Load Transfer

• In one way slab, the load is transferred in one direction.
• In a two-way slab, the load is transferred in both directions.

8. One Way Slab Vs Two Way Slab: Cost

• One-way slabs are economically less expensive than two-way slabs.
• Two-way slabs are economically more expensive than one-way slabs.

9. One Way Slab Vs Two Way Slab: Deflection

• Deflection in a one-way slab gives it a cylindrical shape.
• Deflection in a two-way slab makes it look like a bowl.

10. One Way Slab Vs Two Way Slab: Thickness

• One-way slab thickness can be designed from 4 inches to 6 inches (100 mm to 150 mm) depending on deflection and span.
• The thickness of the two-way slab can be designed from 4 inches to 8 inches (100 mm to 200 mm) depending on the deflection and span.

11. One Way Slab Vs Two Way Slab: Reinforcement Placing

• In one way slab, main reinforcement is placed in a short span, and distributions reinforcement is placed in a long span.
• In two way slab, the main reinforcement is placed in a short span and a long span.

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What Is a Slab in Building Construction?

What Are the Functions of a Slab in Construction?

What Are the Different Types of Slabs Based on Support Conditions?