Building Components and Structures

1. UNIT 5 BUILDING COMPONENTS AND
STRUCTURES
Department of Mechanical Engineering
Prepared By
Mr. S.Maniraj M.E.,(Ph.D)
Assistant Professor
Paavai Engineering College

2. BUILDING
COMPONENTS
1. Sub structure
2.Super structure

3. 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

4. FOUNDATION
 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
1. Bearing capacity of
the soil
2. Settlement of
foundations
 Ultimate bearing
capacity
 Safe bearing capacity
 Allowable bearing
capacity
 Uniform settlement
 Differential settlement

9. BEARING CAPACITY
• Supporting power of soil without any failure
• Depends on :
1. Properties of soil
2. Position of water table
3. 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
Uniform settlement is usually of little
consequence in a building, but differential
settlement can cause severe structural damage.
No settlement Total settlement Differential settlement
Settlement of foundations

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 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 foundations

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

28. Raft or mat foundation

29. Mat foundation

30. Raft or Mat Foundation

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

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

34. 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

35. Classification of Piles
1. Method of load transfer
2. Function or action
3. Composition and material
4. Installation

36. Classification based up on method of load
transfer
1. End bearing Piles
2. Friction Piles

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

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

39. Classification based up on material and
composition
1. Timber Piles
2. Steel Piles
3. Concrete Piles
4. Composite Piles

40. Timber Piles
 Timber Piles perform well both in dry condition and
in submerged condition

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

42. Concrete Piles

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

44. 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

45.  The bottom edge of the well foundation consists of
a cutting edge. The different c/s adopted for well
foundations are
1. Circular
2. Twin circular
3. Double D
4. Dumb bell
5. Twin hexagonal
6. Rectangular

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

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

48.  Well curb
 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

51.  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
Machine foundation

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

53. BLOCK TYPE BOX TYPE
WALL TYPE FRAMED TYPE

54. THANK YOU