This is about slab and its types

1. PROJECT TITLE : SLAB

2.  SAJJAD ASLAM
 SABIR BALOCH
 MOHAMMAD ASIM
 WAHEED AHMED

3.  In reinforced concrete construction, slabs are used to
provide flat, useful surfaces.
 A reinforced concrete slab is a broad, flat plate, usually
horizontal, with top and bottom surfaces parallel or nearly so.
 It may be supported by reinforced concrete beams by
masonry or reinforced concrete walls, by structural steel
members, directly by columns, or continuously by the ground.

4.  A concrete slab is common structural element of modern
buildings. Horizontal slabs of steel reinforced concrete,
typically between 4 and 20 inches (100 and 500 millimeters)
thick, are most often used to construct floors and ceilings,
while thinner slabs are also used for exterior paving.

5. SLAB
ONE WAY
TWO WAY

6. 1. One way slab is supported by beams in only 2 side.
2. The ratio of longer span panel (L) to shorter span panel (B) is
equal or greater than 2. Thus, L/B >= 2.
3. Main reinforcement is provided in only one direction for one
way slabs.
4. One way slabs will behave in the same manner as a support
beam.
5. Main steel is only provided parallel to span

9.  Check whether the slab is one-way or two-way.
 Calculate h(min).
◦ Not less than 110 mm for rooms
◦ Not less than 75 mm for sunshades
 Calculate dead load acting on the slab
◦ Calculate dead load acting on the slab
 Calculate live load acting on the slab.
 Calculate total factored load per unit strip (KN/m)

10.  Calculate the moments either directly (simply supported) or by
using coefficient for continuous slabs
 Calculate effective depth.
d = h – (20 + (½)db)
db = 10, 13, 15 generally used

11.  Minimum Slab Thickness:
For solid nonprestressed slabs overall slab thickness h, shall
not be less than the limits in the table.
Support Condition Minimum h
Simply Supported l/20
One end continuous l/24
Both end continuous l/28
Cantilever l/10

12.  Two way slab is supported by beams in all four sides.
 The ratio of longer span panel (L) to shorter span panel (B) is less
than 2 Thus, L/B < 2.
 Main reinforcement is provided in both the directions for two
way slabs.
 Two way slabs will reduce bending and shifting.

15.  Flexibility in room layout
 Reinforcement placement is easier
 Ease of Framework installation
 Building height can be reduced
 Less construction time

16.  Span length is medium.
 Not suitable for supporting brittle (masonry) partitions
 Higher slab thickness
 Critical middle strip deflection

17. For each applicable factored load combination, design strength
at all sections shall satisfy:
1. ∅Sn≥U
2. ∅Mn≥Mu
3. ∅Vn≥Vu

18.  The Direct Design method consists of a set of rules for
distributing moments to slabs and beam sections to satisfy
requirements and most serviceability requirements
simultaneously. These fundamental steps are involved as
follows:
 Determination of the total factored static moment.
 Determination of the total factored static moment to negative
and positive sections
 Distribution of the negative and positive factored moments to
the column and middle strips and to the beams, if any.

19.  There shall be a minimum of three continuous spans in
each direction.
 Panels shall be rectangular, with the ratio of longer to
shorter span not greater than two.
 All loads shall be due to gravity only and uniformly
distributed over an entire panel. The unfactored live load
shall not exceed two times the unfactored dead loads.