# Introduction of Two Way Slab

There are various types of slab used in construction, out of which two way slab is the most commonly used slab. It is referred to as a two way slab because the weight of the slab is borne equally by two supporting beams. Following are the key points that should be kept in mind while designing a two way slab.

## What is Two Way Slab

• Two way slab is a type of slab which is supported by beams on all the four sides and the loads are carried by these beams to the columns
• Two way slab is classified as a simply supported beam
• There are two types of two way slab, waffle slab and flat slab
• Waffle slab has a series of troughs and beams in both directions while the flat slab has no beams or troughs.

## Types of Two Way Slab

• A two-way slab is a slab that is supported by beams on all four sides and reinforced in both directions with steel rebar
• The weight of the slab is evenly distributed across the beams, and the beams distribute the weight to the supporting columns
• Two-way slab construction is most common in medium to high-rise buildings, where the added strength and stability of the beams is necessary to support the weight of the structure.

## Reinforcement Detailing of Two Way Slab

• When two way slab is supported on both sides then it is called two way slab
• If a slab is supported on all the four sides then it is termed as four way slab
• Two way slab is basically of following two types:

1

• One way slab
2
• Two way slab

One way slab is supported on only two opposite sides while a two way slab is supported on all the four sides.

The main criterion for the design of two way slab is the loads which it has to bear

• Two way slab is subjected to both dead and live loads
• Dead loads are those which are permanent in nature like self weight of slab etc
• On the other hand, live loads are those which are changeable in nature like human occupancy, wind load, snow load etc.

Based on the loads, two way slab is designed for different span lengths

• Slab with shorter span to depth ratio is called shallow slab while slab with larger span to depth ratio is termed as deep slab.

Reinforcement Detailing of Two Way Slab:

1

• Short span slab: In case of short span slab, the dangerous conditions arise at the supports only
• So, the arrangements of reinforcement are to be made at the supports only
• The reinforcement should be placed in the form of beam at the corners and edges of the slab.

2

• Deep slab: In case of deep slab, the dangerous conditions arise at the middle of the span as well

## Steps in Two Way Slab Design

• There are several steps that must be completed in order to properly design a two way slab
• First, the designer must determine the loads that will be applied to the slab
• Next, the soil conditions must be evaluated to determine the soilâ€™s bearing capacity
• Once the loads and soil conditions are known, the designer can select the appropriate thickness and reinforcement for the slab
• Finally, the dimensions of the slab must be determined in order to properly place the reinforcement.

## Conclusion

Two-way slab is a reinforced concrete slab supported by beams on all four sides. It is usually used for floors in office buildings, apartment buildings, and hotels. Two-way slab young’s modulus calculator is a tool to help determine the necessary thickness of the slab. The Two-way slab may be considered as a beam-and-slab system with the slab spanning in two directions and the beams spanning in the other two directions.