A Flat Slab can also be refers to as Beamless Slab, It is a reinforced concrete slab supported directly by concrete columns without the use of beams. A plain ceiling is obtained thus giving attractive appearance from an architectural point of view.
Flat slab is defined as one sided or two-sided support system with sheer load of the slab being concentrated on the supporting columns and a square slab called ‘drop panels’. The Drop panels play a significant role here as they augment the overall capacity and sturdiness of the flooring system beneath the vertical loads thereby boosting cost effectiveness of the construction. Usually the height of drop panels is about two times the height of slab.
The flat slab is easier to construct and requires less formwork. This is one of the types of concrete slabs. If possible, try to do away with drop panels as much as possible and try to make the best use of thickness of flat slabs. The reason is to permit the benefits of flat soffits for the floor surface to be maintained, ensure drop panels are cast as part of the column.
The thickness of the Flat slab is minimum of 0.2m / 200mm
TYPES OF FLAT SLAB
[1] SIMPLE FLAT SLAB
This is a type of flat slab that doesn’t have either the column heads or the Drop Panels
[2] FLAT SLAB WITH DROP PANELS
This is a type of flat that have a drop panel between the column and the slab.
Uses of Drop Panels
- It increase shear strength of slab
- It increase negative moment capacity of slab
- It stiffen the slab and hence reduce deflection
[3] FLAT SLAB WITH COLUMN HEADS
This is a type of flat slab that have a column head between the column and the slab
Uses of Column Heads
- It increase shear strength of slab
- It reduce the moment in the slab by reducing the clear or effective span
[4] FLAT SLAB WITH BOTH DROP PANELS AND COLUMN HEADS
This type of flat slab comprises both the drop panels and the column Head. Combining the two increase more shear strength of the slab and same time reduce deflection.
ADVANTAGES OF FLAT SLAB
[1] Flexibility in Layout.
[2] Reinforcements placement is Easier.
[3] Ease of Formwork Installation.
[4] Reduce Building Heights.
[5] Less Construction Time.
[6] Auto Sprinkler is Easy.
DISADVANTAGES OF FLAT SLAB
[1] Span Length is Medium (No Large Span).
[2] Flat Slab is not suitable for support Brittle / Masonry Partitions.
[3] Critical Middle Strip Depletion may Occur.
[4] Higher Slab thickness compare to typical reinforced concrete Two way slab.
AREA OF APPLICATION OF FLAT SLAB
[1] To provide plain ceiling surface giving better diffusion of light.
[2] Easy constructability with the economy in the formwork.
[3] Larger headroom or shorter storey height & pleasing appearance.
[4] This kind of slabs are provided in parking.
[5] Flat slabs are generally used in parking decks, commercial buildings, hotels or places where beam projections are not desired.
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