foundations

1. TYPES OF FOUNDATIONS
BY:
DEENA THAYALAN T
( 15TA2212 )

2. CONTENTS :
Definition.
Functions & Types of foundations.
Classifications & Materials used.
Suitable foundation for the various type of soils.

3. FOUNDATION :
Foundation is the lowest part of building.
Used to Distributes the weight of Super-Structure
to the soil.
Also called as Sub - Structure.

4. FUNCTIONS :
 Distribution of loads.
 Stability against sliding and overturning.
 Minimize differential settlement.
 Safe against undemining.
 Provide level surface.
 Minimize distress against soil movement.

6. TYPES OF SHALLOW FOUNDATION :
1. Isolated Footing
2. Combined Footing
3. Mat (or) Raft Footing
4. Strap Footing

7. 1. ISOLATED FOOTING
 Used to support a single column
 It is an independent footing.
 It consists of Bottom slabs.
 It is suitable for loose sand
and gravel.
 Cover should not be less
than 50mm.
 Dia of main reinforcement
shall not less than 10mm.

8. STRIP FOOTING :
 A continuation of pad footing is called
strip footing (or) wall footing.

9. 2.COMBINED FOOTING
It is constructed for two (or) more
columns when close to each other.
Number of columns carries a single
spread footing.
Used when SBC is low.
It may be rectangular,
trapezoidal & Tee -shaped.
Trapezoidal footing is
provided when one
column load is greater than
other.

10. 3. MAT (OR) RAFT FOOTING
It is preferable in low
bearing soils (clay,
loose sands).
Types -Flat plate mat,
1. Plate thickness under
column, 2. Two-way beam
and slab, 3. Plate with
pedestals, 4. Rigid frame
mat & 5. Piled raft.
Used in Silo's, chimney, tower structures, etc.

11. 4. STRAP FOOTING
Also it called as Cantilever
footing.
Connects two (or) more
column footings by a
concrete beam.
Used to transfer the
column loads on to the
soil with equal & Uniform
soil pressure under both
footings.

12. GRILLAGE FOOTING

13. STANCHIONS

15. GRILLAGE FOOTING
A Foundation where iron rails &
structural beams are combined
in a Crisscross pattern.
Used in huge loaded structures
on a soil has low bearing
capacity.
A type of Shallow foundation.
TYPES:
1. Steel grillage foundation.
2. Timber grillage foundation.

16. TYPES OF DEEP FOUNDATION :
1. Pile Foundation.
3. Well Foundation (or) Caissons.
2. Pier Foundation (or) Drilled caisson.
4. Diaphragm Foundation.

17. PILE FOUNDATION:
1. Classification Based On Functions.
2.Classification Based On Materials.
It is an Columnar structure used to transfer the
loads from superstructure at where the
required bearing capacity is available.
It is used where there is a danger of scouring
action of water.
TYPES OF PILE FOUNDATION:

18. Pile Classification Based On Functions.
1. End Bearing Pile. 2. Friction Pile.
4. Tension Pile.
3. Compaction Pile.
6. Fender Pile.
5. Anchor Pile.
8. Sheet Pile.
7. Batter Pile.

19. 1. End Bearing Pile.
 Used to transfer the load
through water (or) soft
soil at the toe of the pile
to a suitable hard bearing
stratum .

20. 2. Friction Pile.
 Also it called as Floating
pile (or) Cohesion pile.
 Used to transfer loads to
a depth through Skin
friction along the length
of pile.
 Used in Low-Medium
dense sand at where hard
strata is available.

21. 3. Compaction Pile.
 Used to compact loose
granular soil to increase their
bearing capacity.
 Compaction pile donot carry
load and hence they are
weaker material.

22. Pile Classification Based On Materials.
1. Concrete Pile.
3. Steel Pile.
2. Timber Pile.
4. Composite Pile.

23. 1. Concrete Pile.
Cast - in - situ
Pre - Cast
Bored Piles
( Pressure piles ,
under reamed piles )
Driven Piles
( Cased or Uncased )

24. 3. Steel Pile.
Pipe Pile
H - Pile
Screw Pile

25. 4. Composite Pile.
Concrete And Steel
Concrete And Timber

26. 3. Well Foundation (or) Caissons.
 It is more suitable to
the deep foundation
under water.
 Used to construction
marine structures,
bridges,abutment in
lakes/river,etc.
 Occasionally used for
Multi-storey buildings
and other structures .

27. Types of Caissons
Box Caisson
Open Caisson
Pneumatic caisson