This document discusses different types of slabs used in construction. It defines slabs as structural members that provide flat horizontal surfaces. The main types discussed are one-way slabs, which are supported by beams on two sides, and two-way slabs, which are supported on all four sides. The document provides details on the load transfer and reinforcement of each type of slab, and compares the key differences between one-way and two-way slabs. It also briefly discusses grid slabs and defines mechanisms of load transfer in slabs.

1. amirbaloch

2. Table Of Contents
P.03:
Figure of Slab in a construction site
P.04:
What is Slab?
P.06:
Types Of Slab
P.07:
What Is a One-way slab?
P.09:
What is a Two-Way Slab?
P.13:
What is Grid Slab?
P.14:
Difference Between One-way Slab and Two-way
Slab
P.15:
Mechanism of load Transfer in Slab
P.16:
Quick FAQ's on each topic
About the Presentation
This Presentation will Explain you
What is slab and difference between
types of slabs. After reading all the
slides I'm definitely sure your slab
concept is fully solved.
In this civil experience, I will explain
the difference between one way slab
and two way slab (One way slabs vs
Two way slabs) in detail also provide
one way slab and two way slab Table.
Before going on a particular type of
slab take an eye on what is slab and
understand its mechanism.
NOTE : Feel free to share with civil engineers,
Structural engineers and follow me for more
important learning.
amirbaloch

3. Fig 1. The above figure is the representation of a slab in construction Site
amirbaloch

4. 1) WHAT IS SLAB?
A slab is a structural member to provide flat horizontal surfaces in luxury building
floors, roofs, bridges, and other types of structures.
Fig 1. Graphical Representation Of Slab. Fig 2. Graphical Representation Of Slab, Column, Beams & Roof.
amirbaloch

5. A) MORE DETAILS ON SLAB
• The slab rest on walls, by reinforced concrete beams normally cast monolithic
ally with the slab, by structural steel beams, either by columns or from the
ground.
• A slab thickness and it is supported by other structural elements like RC
columns, RC beams, walls, or the ground surface.
• The cement concrete slab with top and bottom surfaces are parallel. The depth
of a concrete slab is very small compared to its span or length.
• In the building component, there are two major types of slabs used in building
construction one-way slabs and two-way slabs.
• In the building component, there are two major types of slabs used in building
construction one-way slabs and two-way slabs.
amirbaloch

6. 2) TYPES OF SLABS BASED ON SUPPORT CONDITIONS
1. One-way Slab
2. Two-Way Slab
3. Flat Slab ( Resting Direction on a Column without Beam
4. Grid Slab or waffle Slab
5. Circular Slab and Other Shapes
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7. 3) WHAT IS A ONE-WAY SLAB?
One-way slab is supported by only two parallel beams or walls.
A one way slab is defined as a flexural member with thickness small relative to other slab dimensions, gravity loads applied normal
to and directly above slab surface, a span in one direction between parallel supports, and fortified for flexure in this direction only.
Fig 1. Graphical Representation Of One-Way Slab. Fig 2. Graphical Representation Of One-Way Slab Explained.
EDGE 01
EDGE 02
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8. ONE WAY SLAB DEFINITION:
The one-way slab is a slab, which is supported by parallel walls or beams, and
whose length to breadth ratio is equal to or greater than two and it bends in only
one direction (spanning direction) while it is transferring the loads to the two
supporting walls or beams, because of its geometry. Simply stating it spans and
bends in only one direction.
ONE WAY SLAB REINFORCEMENT DETAILS :
• Commonly a One-Way Slab, as one side is greater than the other one, the
utmost load will be transmitted by the larger side. Accordingly, it is necessary to
contribute sufficient support to the larger side.
• To provide sufficient support to the extended side, the main reinforcement bars
are placed parallel to the shorter side and the distribution bars are placed on
the longer side which does not support transmitting the load.
• So, a one-way slab is chosen where main bars or cranked bars are provided on
the shorter side of the slab due to bending. Distribution bars (straight bars) are
provided on the longest side as shown in the figure.
amirbaloch

9. 4) WHAT IS A TWO-WAY SLAB?
A two-way slab is a street that allows the load to travel in both directions. The design
considerations of wall-supported two-way slabs are similar to one-way slabs.
Fig 1. Graphical Representation Of Two-Way Slab. Fig 2. Graphical Representation Of Two-Way Slab Explained.
EDGE 01
EDGE 02
EDGE 03
EDGE 04
amirbaloch

10. A) DETAILS ON TWO-WAY SLAB
• The thickness of the slab is generally based on deflection control criteria, and
the reinforcements in the two orthogonal directions are designed to resist the
calculated maximum bending moments in the respective directions at the
critical sections.
• Additional reinforcement may be required at the corners of two way slabs in
some cases, as explained later.
• You can recognize the main bars are placed on both sides. The RCC slab is held
up by beams on every four sides and the loads are upheld by structural
components such as beams along with both directions.
• The slab thickness should be sufficient against shear, although shear is usually
not a problem in two way slabs subjected to uniformly distributed loads.
• If the slab is supported at all four edges and if Ly/Lx < 2, (two way slab formula)
• The tendency of the slab is to bend in both directions. Such slab is called two
way slab.
• In two way slabs, main reinforcement is provided along with Lx as well as Ly
direction
amirbaloch

11. A) TWO-WAY SLAB REINFORCEMENT DETAILS
• In the 2 way slab, as the loads are acting in both direction i.e. longer and shorter
directions.
• In this type of slab, the main reinforcement bars are laid in both directions. The
loads held up by two sides in this type of slabs are equal.
• You can recognize the main bars are placed on both sides. The RCC slab is held
up by beams on every four sides and the loads are upheld by structural
components such as beams along with both directions.
• Slab with reinforcement steel in both directions is more practicable and
supportive than one-way reinforcement slabs.
amirbaloch

12. B) TYPES OF TWO-WAY SLAB
1. Interior panel
2. One short edge discontinuous
3. One long edge discontinuous
4. Two adjacent edges discontinuous
5. Two short edges discontinuous
6. Two long edges discontinuous
7. Three edges discontinuous(one long edge continuous)
8. Three edges discontinuous(one Short edge continuous)
9. Four edges discontinuous
amirbaloch

13. 5) WHAT IS GRID SLAB?
• When the slab is supported on beams with column only on the periphery of the
hall, the slab is called a grid slab. Sometimes, in large halls, public places,
marriage halls, auditoriums, etc. a large column free area is required.
• In these cases, large deep beams may be permitted, but the columns are
permitted only on the periphery.
amirbaloch

14. 6) DIFFERENCE BETWEEN ONE-WAY SLAB AND TWO-WAY SLAB?
amirbaloch
One Way Slab Two Way Slab
The one way slab is supported
by a beam on two opposite
side only.
The two way slab is supported
by the beam on all four sides.
The utmost load is carried by
the larger side.
The loadings are imposed and
held up in both directions
i.e. longer and shorter
directions.
Ly/Lx ≥ 2 one way slab
spanning.
Ly/Lx < 2 two way slab
spanning
In one way slab, the load is
carried in one direction
perpendicular to the supporting
beam.
In two way slab, the load is
carried in both directions.
If L/b the ratio is greater than or
equal to 2 or then it is
considered a one-way slab.
If L/b the ratio is less than 2
then it is considered a two-way
slab.
One way slab two opposite
side support beam /wall
Two Way Slab four side mins
all side supported beam /wall
One way slab is bent only in
one spanning side direction
while load transfer
In two-way slab, the crank is
provided in four directions.
One Way Slab Two Way Slab
In one-way slab, the load is
carried in one direction
perpendicular to the supporting
beam.
In two-way slab, the load is
carried in both directions.
The deflected shape of the
one-way slab is cylindrical.
Whereas the deflected shape
of the two-way slab is a dish or
saucer-like shape.
In one-way slab quantity of
steel is less.
In two-way slab quantity of
steel is more as compared to
the one-way slab.
Main Reinforcement is in
provide short span due to
banding.
Main Reinforcement is in
provide short span due to
banding
One way slab near about
100mm to 150mm based on
the deflection.
Two way slabs are in the range
of 100mm to 200mm
depending upon
One way slab economical near
about 3.5 m.
Two way slab may be
economical for the panel sizes
near about 6m x 6m.
Chajja and Varandha are
practical examples of the one
way slab.
Whereas two-way slabs are
used in constructive floors of
the Multistorey building.

15. 7) MECHANISM OF LOAD TRANSFER IN SLAB
• The forces transfer from slab to beam occur in one way or two ways. The whole
system completely depends on the geometrical dimensions of the slab.
• If slabs may be supported by columns only, in this case, two-way action will
prevail.
• If the ratio of long side / short side > 2 it is considered as one-way slab, and if
longer side to shorter side ratio < 2 then it is considered as a two-way slab.
• The load transfer mechanism from concrete slab floor to supporting elements
for one-way slab and two-way slab is shown in the figure.
Reinforcement Details In Slab :
Reinforcement arrangement in a slab is the main parameter to understand the system of forces and safely distribute the loads coming
on the slab.
amirbaloch

16. •
Quick FAQ's on Each topic
1) WHAT IS SLAB?
A slab is a structural member to provide flat horizontal surfaces in
luxury building floors, roofs, bridges, and other types of structures.
2) WHAT ARE THE TYPES OF SLABS BASED ON SUPPORT
CONDITIONS?
1. One way Slab
2. Two Way Slab
3. Flat Slab ( Resting Direction on a Column without Beam
4. Grid Slab or waffle Slab
5. Circular Slab and Other Shapes
3) WHAT IS A ONE-WAY SLAB?
One way slab is supported by only two parallel beams or walls.
4) DEFINE ONE-WAY SLAB?
The one-way slab is a slab, which is supported by parallel walls or
beams, and whose length to breadth ratio is equal to or greater than
two and it bends in only one direction (spanning direction) while it is
transferring the loads to the two supporting walls or beams,
because of its geometry. Simply stating it spans and bends in only
one direction.
5) WRITE DOWN THREE REINFORCEMENT DETAILS OF ONE-WAY
SLAB?
1) Commonly a One-Way Slab, as one side is greater than the other
one, the utmost load will be transmitted by the larger side.
Accordingly, it is necessary to contribute sufficient support to the
larger side.
2) To provide sufficient support to the extended side, the main
reinforcement bars are placed parallel to the shorter side and the
distribution bars are placed on the longer side which does not
support transmitting the load.
3) So, a one-way slab is chosen where main bars or cranked bars are
provided on the shorter side of the slab due to bending. Distribution
bars (straight bars) are provided on the longest side as shown in the
figure.
6) WHAT IS A TWO-WAY SLAB?
A two-way slab is a street that allows the load to travel in both
directions. The design considerations of wall-supported two-way
slabs are similar to one-way slabs.
7) WRITE DOWN 5 DETAIL POINTS ON TWO-WAY SLAB?
1) The thickness of the slab is generally based on deflection control
criteria, and the reinforcements in the two orthogonal directions are
designed to resist the calculated maximum bending moments in the
respective directions at the critical sections.
2) Additional reinforcement may be required at the corners of two
way slabs in some cases, as explained later.
3) You can recognize the main bars are placed on both sides.
The RCC slab is held up by beams on every four sides and the loads
are upheld by structural components such as beams along with both
directions.
4) The slab thickness should be sufficient against shear, although
shear is usually not a problem in two way slabs subjected to
uniformly distributed loads.
5) If the slab is supported at all four edges and if Ly/Lx < 2, (two way
slab formula)
8) WRITE DOWN 4 REINFORCEMENT DETAILS OF TWO-WAY SLAB?
1) In the 2 way slab, as the loads are acting in both direction i.e.
longer and shorter directions.
2) In this type of slab, the main reinforcement bars are laid in both
directions. The loads held up by two sides in this type of slabs are
equal.
3) You can recognize the main bars are placed on both sides.
The RCC slab is held up by beams on every four sides and the loads
are upheld by structural components such as beams along with both
directions.
4) Slab with reinforcement steel in both directions is more
practicable and supportive than one-way reinforcement slabs.
9) WHAT ARE THE TYPES OF TWO-WAY SLAB?
1. Interior panel
2. One short edge discontinuous
3. One long edge discontinuous
4. Two adjacent edges discontinuous
5. Two short edges discontinuous
6. Two long edges discontinuous
7. Three edges discontinuous(one long edge continuous)
8. Three edges discontinuous(one Short edge continuous)
9. Four edges discontinuous
10) WHAT IS GRID SLAB?
When the slab is supported on beams with column only on the
periphery of the hall, the slab is called a grid slab. Sometimes, in
large halls, public places, marriage halls, auditoriums, etc. a large
column free area is required.
11) MAKE A TABLE AND WRITE 7 DIFFERENCE BETWEEN ONE-WAY
SLAB AND TWO-WAY SLAB?
12) WHAT ARE THE MECHANISM OF LOAD TRANSFER IN SLABS?
1) The forces transfer from slab to beam occur in one way or two
ways. The whole system completely depends on the geometrical
dimensions of the slab.
2) If slabs may be supported by columns only, in this case, two-way
action will prevail.
3) If the ratio of long side / short side > 2 it is considered as one-way
slab, and if longer side to shorter side ratio < 2 then it is considered
as a two-way slab.
4) The load transfer mechanism from concrete slab floor to
supporting elements for one-way slab and two-way slab is shown in
the figure.
THANK YOU NOTE :
Thank you for reading all my slides. I hope you enjoyed my presentation about “What Is slab?” And
understood the topic very well. If you have any questions regarding my slides make sure you write it
down in the comments below. I would love reply there. Most important thing do share this with your
fellow Civil engineers, Structural engineers & architectures.
amirbaloch
One-Way Slab Two-Way Slab
The one way slab is supported by
a beam on two opposite side only.
The two way slab is supported by
the beam on all four sides.
The utmost load is carried by
the larger side.
The loadings are imposed and
held up in both directions
i.e. longer and shorter directions.
Ly/Lx ≥ 2 one way slab spanning. Ly/Lx < 2 two way slab spanning
In one way slab, the load is
carried in one direction
perpendicular to the supporting
beam.
In two way slab, the load is carried
in both directions.
If L/b the ratio is greater than or
equal to 2 or then it is considered
a one-way slab.
If L/b the ratio is less than 2 then it
is considered a two-way slab.
One way slab two opposite side
support beam /wall
Two Way Slab four side mins all
side supported beam /wall
One way slab is bent only in one
spanning side direction while load
transfer
In two-way slab, the crank is
provided in four directions.