1. BUILDING COMPONENTS
Sub structure
Super structure

2. Sand Filling
Brick Masonry
Floor Finish
Foundation concrete
Ground Level
Step
Plinth
Floor Concrete
Basement
Door
Lintel
Roof Slab
Parapet
Weathering Course
COMPONENTS OF A BUILDING
Damp Proof Course
Foundation

3. FOUNDATION

4. Foundation is the part of the structure which is in direct contact with the ground to which loads are transmitted.

5. A weak foundation destroys the work which is built upon it.

6. Functions of foundation
Even distribution of load
Reduction of load intensity
Reduction of differential settlement
Safety against sliding and overturning
Safety against undermining
Provide firm and level surface
Protection against soil movement

7. Requirements of a good foundation
Constructed to sustain dead load and imposed load and transmit them to underlying soil
Rigid-to avoid differential settlement
Taken to sufficient depth
Performance should not be affected due to any unexpected future influence

8. Factors for the design Ultimate bearing capacity
Safe bearing capacity
Allowable bearing capacity
Uniform settlement
Differential settlement
Bearing capacity of the soil
2. Settlement of foundations

9. BEARING CAPACITY Supporting power of soil without any failure
Depends on :
Properties of soil
Position of water table
Physical features of foundation like type, size & shape
Ultimate Bearing Capacity : minimum gross pressure intensity at the base of foundation that the soil fails in shear
Net Ultimate Bearing Capacity : minimum net pressure intensity at which the soil fails in shear
Net safe bearing capacity : obtained by dividing the net ultimate bearing capacity of the soil with a suitable factor of safety
Safe bearing capacity : Maximum pressure the soil can carry safely without the risk of shear failure

10. Settlement of foundations
No settlement
Total settlement
Differential settlement
Uniform settlement is usually of little consequence in a building, but differential settlement can cause severe structural damage.

11. Settlement of foundation means the sinking of foundation as a consequence of compression or deformation of the soil under the foundation
Equal Settlement :
The structures settles by uniform amount at each and every portion of the structure
Unequal Settlement:
The amount of settlement is different at different parts of the building

12. Causes of differential settlement:
Causes of settlement:
Due to weight of the structure transmitted to the soil
Due to increased load on the surrounding soil
Due to excavation near the foundation
Lowering of water table
Vibrations from moving machineries
Deterioration of concrete by the chemical action of soil, seawater etc…
Due to mining and tunnelling operations
Causes of differential settlement:
Non uniform load distribution on foundations
Non uniformity of soil types
Percolation of water
Overlap and concentration of stresses due to presence of adjacent foun dations

13. Causes of foundation failure
Unequal settlement of subsoil under the foundation
Unequal settlement of the masonry
Lateral movement of earth
Shrinkage of soil bed due to seasonal variation of moisture content
The penetration of the roots of trees
Atmospheric action
Lateral escape of the soil beneath the foundation
Horizontal movement of the soil adjacent to the structure

14. Types of Foundations Shallow Foundations D<=B
Deep Foundations D>B
D - Depth of foundation
B – Width of foundation

15. Shallow foundations Types of shallow foundations
Isolated or column footing
Wall or strip footing
Combined footing
Continuous footing
Cantilever footing
Raft or mat foundation

16. Isolated or column footing
When the load on the column is less, a spread is given under the column

18. Wall or strip footing
The foundation which is provided through out the length of a continuous structure is called strip footing.

20. Combined footing
When a foundation or footing is constructed for two or more columns is called as combined footing
Two individual footings overlap
When bearing capacity is less
when footings are constructed
near boundaries of the plot
Trapezoidal footing – when column
loads vary considerably

22. Continuous footing
A single continuous reinforced concrete slab is provided as foundation for three or more columns in a row. Continuous footing is more suitable to prevent the differential settlement in the structure and for the safety against earthquake.

23. Continuous footing

24. Cantilever Footing (Strap)
Consists of an eccentric footing for the exterior column and a concentric footing for the interior column.
A strap or a cantilever beam connects them.

25. Strap footing

27. Raft or mat foundation
A raft foundation is a combined footing which covers the entire area beneath a structure and supports all the walls and columns

28. Raft or mat foundation

29. Mat foundation

30. Raft or Mat Foundation

33. Raft foundations are suitable when
The building loads are heavy
The allowable soil pressure is small
Individual footings would require more than half the building area
In highly compressible soil
Weak spots and loose pockets in soil mass are suspected

34. Deep Foundation
The foundations having very large depth compared to width are called deep foundations
E.g. Pile foundations
Well foundations

36. Pile Foundation
Piles are long slender members driven into ground or cast at the site. Pile foundations are common where the soil conditions are unfavorable for the use of shallow foundations

37. Suitability of pile foundations
Loose foundation soil but hard strata is available at a depth of m
Heavy dead and live loads
Near seashore or riverbed where scouring action of water occurs
Position of water table is likely to fluctuate appreciably
Canals or deep drainage lines near by

38. Classification of Piles
Method of load transfer
Function or action
Composition and material
Installation

39. Classification based up on method of load transfer
End bearing Piles
Friction Piles

40. End bearing piles
End bearing piles-Used to transfer load to a suitable bearing stratum

41. Friction piles
Friction Piles- used to transfer the loads to a depth by friction along the surface area of the piles.

42. Classification based up on function or use
Compaction Piles
Tension or uplift piles
Anchor Piles
Fender Piles
Sheet Piles

43. Compaction Piles

44. Anchor Piles and Tension piles
Used to anchor structures subjected to hydrostatic pressure (against pilling or pushing forces)
Anchor Piles and Tension piles

45. To protect water front structures like docks, harbours etc… against impact from ships
Fender Piles

46. Used to retain the sides of excavation, to prevent seepage below dams, to construct retaining walls etc.
Sheet Piles

47. Classification based up on material and composition
Timber Piles
Steel Piles
Concrete Piles
Composite Piles

48. Timber Piles perform well both in dry condition and in submerged condition

49. Used to resist lateral or horizontal forces. More durable.
Steel Piles

50. Concrete Piles

51. Used when part of the pile is submerged under water
Used when part of the pile is submerged under water. Made up of concrete and steel
Composite Piles

52. Classification based upon installation
Precast Piles
Cast In Situ Piles

53. Precast Piles

54. CAST IN SITU PILES
CASED CAST IN SITU PILES
UNCASED CAST INSITU PILES

55. Well Foundations
A well foundation is a well type structure, which built at the ground level and sunk into the soil at the required level.
The bridge pier will be resting on the top of the well foundation.
The bottom of the well is plugged with concrete.
The top is covered with a well cap which is a thick concrete slab

56. The bottom edge of the well foundation consists of a cutting edge
The bottom edge of the well foundation consists of a cutting edge. The different c/s adopted for well foundations are
Circular
Twin circular
Double D
Dumb bell
Twin hexagonal
Rectangular

57. Components of well foundation
Well curb
Cutting edge
Steining
Bottom plug
Top plug
Well cap

58. WELL CAP
TOP PLUG
STEINING
SAND OR SOIL FILLING
WELL CURB
BOTTOM PLUG
CUTTING EDGE

59. Well curb Cutting edge Steining Bottom plug Top plug Well cap
Support the wt of the well
Cutting edge
Sharp angle for cutting the soil without making it too weak
Steining
Walls of the well
Bottom plug
Concrete plug provided to balance the soil pressure
Top plug
Concrete plug provided above the sand/soil filling
Well cap
Serves as platform for the supporting members of the superstructure

62. Well sinking operations
Laying the well curb
Construction of masonry in wall steining
Well sinking
Completion of well

63. Soil excavation

64. Construction of well cap

65. Machine foundation
To support the dynamic forces produced by the operation of the machine
To avoid large settlements at resonance, natural frequency of foundation should be different operating frequency of the machine

66. Types of machines Impact type Reciprocating type Centrifugal type
Presses, forge hammers
Reciprocating type
Compressors, engines
Centrifugal type
Motors, turbines
Miscellaneous types
Machine foundation

67. BLOCK TYPE
BOX TYPE
WALL TYPE
FRAMED TYPE

69. DETERMINATION OF
BEARING CAPACITY

70. Plate load test

71. Plate load test

72. PLATE LOAD TEST
It is a field test used to determine the ultimate bearing capacity of soil
A pit is dug up to the foundation level
A square plate of 300mm x 300mm & 25 mm is placed at the centre of the pit
A dial gauge is connected to the test plate
Now weights in the form of sand bags are placed on the platforms in equal increments.
The test is continued till the failure occurs or the plates settled by 25 mm whichever occurs earlier
The load settlement curve is then recorded.

73. Load v/s settlement graph

74. Standard Penetration Test

75. STANDARD PENETRATION TEST
Test is conducted in a bore hole 50 to 150 mm in diameter
Split spoon sampler (pipe-like weight) is driven into the ground by a weight of 65 kg
weight is repeatedly raised and dropped a distance of 750 mm to drive in sampler
number of blows required to drive the sampler for a penetration of 300mm is recorded
The number of blows is known as penetration number (N Value)
There are empirical charts from which the bearing capacity can be calculated based up on the N Value

76. Methods for improving Bearing Capacity
Compaction
Drainage
Vibratory methods
Chemical stabilisation
Grouting
Geotextiles