The document describes different types of shallow foundations, including spread footings, combined footings, and raft/mat foundations. Spread footings include wall footings, reinforced concrete footings, inverted arch footings, and column footings. Combined footings are used when columns are close together or near a property line. Raft foundations consist of a thick concrete slab covering the entire structure area and are used when soil capacity is low or loads are large. The document also discusses advantages, limitations, and construction procedures of shallow foundations.

3. GROUP NO.01
Name Roll No.
(1) Raktim Barua 10.01.03.123
(2) Farjana Akter 10.01.03.140
(3) Fatema Sultana 10.o1.03.159
(4) Md.Shahadat Hossain 10.01.03.154
(5) Raiyan Fardous Ratul 10.01.03.153
(6) Sajjad Hossain 10.01.03.152
(7) Mehrana Rashid Noor 10.01.03.162
(8) Tuhin 10.01.03.156
(9) Bushra Tasnim 09.02.03.002

4. Foundation:
Foundation is the lowest part of a structure which
provides a base for the super‐structure and transmit the loads
(live load, wing load) on the structure including the dead weight
of the structure itself to the soil below.
Types of Foundation:
Foundation can be broadly classified into two types–
1. Deep Foundations
2. Shallow Foundations

5. Shallow foundations:
Foundation is placed immediately lowest part of the
super structure, is termed as Shallow foundation.
Why we use shallow foundation?
‐ To distribute the structural loads over a wide
horizontal area at a shallow depth below the ground
level.

6. The various types of shallow foundations are :
(a) Spread footing
(b) Combined footing
(c) Mat or Raft foundation.
(d) Grillage footing
(e) Eccentrically loaded footing

7. Spread footings
Spread footings are
structural members used
to support columns and
walls and to transmit and
distribute their loads to
the soil.

8. Types of spread footing
 Wall footings
 Reinforced concrete
footings
 Inverted arch footing
 Column footings

9. Wall Footing

10.  Support walls that
may be either bearing
or nonbearing walls.
 Commonly required
to support direct
concentric loads.
Why Wall Footing?

11. Footings carry
relatively light loads on
well drained cohesive
soil.
A wall footing under
concentric load behaves
similarly to a cantilever
beam.
Used in low rise
buildings.
Why Wall Footing?

12. Reinforced
concrete
footing

13. Why Reinforced concrete
footing?
Relatively heavy loading
than wall footing.
Bearing capacity of the
soil is low.

14. In a reinforced concrete
wall footing, the
behavior is identical to
that of wall footing.
Reinforcing steel is
placed in the bottom of
the footing in a direction
perpendicular to the wall
like a reinforced concrete
beam or slab.
Why Reinforced concrete footing?

15. Inverted arch
footing

16. When a wall is
composed of
isolated piers, it
is well to
combine all their
footings into
one, and to step
the piers down .
Inverted arch footing

17. COLUMN
FOOTINGS

18. WHY COLUMN
FOOTINGS?
 This is one of the most
economical types of
footings.
 Used when columns are
spaced at relatively long
distances.

19. WHY COLUMN
FOOTINGS?
 Low bending
strength.
 When bearing
capacity of soil is
good.
 Carry heavy loads.
 Used to support
single columns.
To distribute the load
uniformly.

20. CHARACTERISTICS
OF COLUMN
FOOTINGS
 Constructed with brick,
stone or plane
concrete.
 Circular, rectangular or
square in plan.

21. PROCEDURE OF COLUMN FOOTINGS
EARTHWORK LEVELING

22. Support
Brick flat soling
9’X9’ Wooded Frame
3”BRICK FLAT SOLING

23. Joint of rod
Wires
BINDING
THE RODS

24. Upper rod
Inner rod
6” interval
POSITION OF RODS
PLAN

25. 3”Clear cover
6”Block
CLEAR COVERS
&
BLOCKS

26. Centering with plumb bob
Ring
Centre point of column
CENTERING THE COLUMN

27. 6” Interval ring
PREPARED COLUMN
REINFORCEMENT

28. Length 17”
Width 9”
LENGTH & WIDTH OF RING

29. PUTTING THE COLUMN INTO THE FOOTING

30. Load bearing support
CAVING TENDENCY

31. LEVELLING THE COLUMN
SUPPORTING THE COLUMN

32. Vibrating
PORING CEMENT CONCRETE

33. A
COMPLETE
COLUMN
FOOTING

34. Combined
footings
Combined footings
usually support two
columns, or three columns
not in a row.
Combined footings are
used when tow columns
are so close that single
footings cannot be used or
when one column is
located at or near a
property line.

35. When two columns
are close together,
causing overlap of
adjacent isolated
footings.
When soil bearing
capacity is low, causing
overlap of adjacent
isolated footings.
WHY COMBINED
FOOTINGS?

36. PROCEDURE OF COMBINED FOOTINGS

37. A COMPLETE
COMBINED FOOTING

38. Foundation which consists of
thick reinforced concrete slab
covering the entire area of the
bottom of the structure like a floor.
This foundation was invented by
John Root at Chicago in 19th
century.
Raft Foundation

39. Why Raft Foundation?
Base soil has low bearing
capacity or the column loads are
so large that more than 50% of
the area is covered by
conventional spread footings.
Resist unequal settlement due to
earthquake.
 Quickness of the construction
work.

40. Figures of the Different Types of Raft

41. PROCEDURE OF MAT FOUNDATION
Plan
Shoring
Excavation of soil
Brick flat soling
or C.C. casting
Formwork &
Placing of
reinforcement
Casting
Curing

42. Before earth can be excavated to make the foundation
certain precaution has to be taken to stop the outside soil
from caving in the excavated area. These precautions are
called shoring , the purpose of which is to anyhow retain
the surrounding soil.
Shoring
process

43. Excavation
Excavate earth
according to design
specification

44. Reinforced chair
Bottom rebar
Top rebar
POSITION OF
REBARS

45. PREPARED COLUMN
REINFORCEMENT
SUPPORTING THE COLUMN
Extra top
rebar

46. Position of column on foundation
Support
Column

47. Formwork for casting
Wooden frame
Support

48. Pouring cement
concrete &
compacting

49. Spread footers being installed too
shallow, oftentimes just 2‐3 feet below
a foundation, which does not eliminate
the effects of expansive soils.
Foundation repair will last longer
than a week as the excavations are
made and the concrete will have to
be cured before the holes can be
refilled.
Limitations of shallow foundation

50. A huge amount of earthwork is to be
done in Mat foundation.
If the shoring system can not resist
the pressure of outside land, then the
structure surrounding the area may be
damaged by deflection of soil.
Ground water may come out when
the earthwork is done.
Limited to dealing with point loads.
Limitations of shallow foundation

51. It is a quick process compared to others in
the construction work.
This type of foundation is also
economically cheaper than any other
foundations.
Though there are some limitations in mat
foundation still it is economical in some
cases.
Advantages of shallow foundation

52. It can resist ground water absorption.
The damage due to earthquake is
lesser than any other type of
foundation.
It consists of a reinforced concrete slab
which is more thicker than footing
foundation.
It prevents unequal settlements.
Advantages of shallow foundation

53. We know shallow foundations are not applicable
for high rise structures, but we saw a lot of high
rise structures which are building upon raft
foundation!
Generally Raft is used when the bearing capacity
of soil is low, but in some sites, we saw raft
foundation is used instead of having a good
bearing capacity!
Conflicts of Our Knowledge
with Our Experiences

55. Questions ? ?