• The basis on which something is grounded
• A lower support of a structure
• The foundation of a building is the soil or rock on
which it sits.
• The footing is that portion of its structure that
serves to transfer the weight of the building
into the ground itself.
• Most foundations extend underground, and the
foundations of large buildings often penetrate to
The design of foundations consists
of 3 essential operations:
• calculating the loads that must be transferred
from the structure to the strata supporting it;
• determining the exact character of subsurface
conditions; groundwater conditions, to a depth
of at least twice the width of the structure; and
• designing a foundation structure that will safely
transfer the loads from the structure to the
foundation beds that have been found at the
Variations in Site Conditions
Subsurface conditions at any building site
can be grouped into three main types:
1. Solid rock - may exist either at ground surface or so
close to it that buildings may be founded directly upon it;
2. Bedrock - may exist beneath the surface but at such a
depth that building loads may, if necessary, be transferred
indirectly to it;
3. Bedrock - may be so far beneath the ground surface
that it is neither practicable nor economical to transfer
building loads to it, the loads having to be carried by the
Material of Foundations
Usually foundation is
made from concrete
TYPES OF FOUNDATION
• Cost (affordable)
• Construction procedure (simple)
• Material used (mostly concrete)
• Workers (doesn‟t need experience)
• Limit capacity „soil‟ structure
• Irregular ground surface (slope,
• Foundation subjected to pullout,
• As a foot of a column/bearing wall
• Under the column and bearing wall
located a layer of concrete slab.
• Only column and bearing wall have
their own individual footing.
• Small area of footing
• Used when surface soils are
sufficiently strong and stiff to support
the imposed loads.
• For the good strength soil, pad
foundation most suitable used to
reduce cost & ease of construction.
• The system: structural load spread
out over a broad area under the
Shape of spread/pad foundation
• Square spread footing
• Rectangular spread footing
• Circular spread footing
• Continuous spread footing
• Combined footing
• Ring spread footing
Square spread footing
• Located a single column & support at
• Concrete mix
• Used to support an individual point load
such as that due to a structural column.
• Usually consist of a block or slab of
• Usually shallow, but deep foundation
also can be used.
Rectangular Spread footing
• Footing with large area
• Especially design for column/bearing
wall which present large load at a
• Rectangle shape.
Circular Spread footing
• Circle shape from plan view but most
to a cylinder with low high.
• Used for light standard, flag poles,
and power transmission lines.
• Especially used for bearing wall which
support large load.
• Long area of footing
• Not for all bearing wall but only for
certain wall according to avoid from
• Design for more than one column
• Column axis is located too close for
each –other-need combine footing.
• Ease of construction.
Ring spread footing
- continuous footings that have been wrapped into
- commonly used to support the walls above-
ground circular storage tanks.
- The contents of these tanks are spread evenly
across the total base area and this weight is
probably greater that the tank itself
A foundation (usually on soft ground)
consisting of an extended layer of
• 1 layer concrete slab that strengthen with
• Used to spread the load from a structure
over a large area.
• Normally consist of concrete slab
which extend over the entire loaded
• Maybe stiffened by ribs or beams.
• Advantage: reduce differential
• Often needed on soft/loose soil with
low bearing capacity as they can
spread the load over a larger area.
To design mat foundation
1. Determine the capacity of the foundation
2. Determine the settlement of foundation
3. Determine the differential settlement
4. Determine the stress distribution beneath
5. Design the structural component of the
mat foundation using the stress
distribution obtain from 4.
• Deep foundations are those founding too
deeply below the finished ground surface
for their base bearing capacity to be
affected by surface conditions, this is
usually at depths >3 m below finished
• Similar in form to pile foundations, but are
installed using a different method.
• Caissons are created by auguring a deep hole
into the ground, and then filing it with
• Drilled either to bedrock or deep into the
under laying soil
• Special drilling bits are used to remove the soil
for these “belled caissons”
• Diaphragm walls are underground
structural elements commonly used for
retention systems and permanent
• Diaphragm walls are constructed using the
slurry trench technique. The technique
involves excavating a narrow trench.
• Slurry trench excavations can be
constructed in all types of soil.
Diaphragm wall construction
begins with the trench being
excavated in discontinuous sections
Panels are usually 8 to 20 feet
long with widths varying from 2 to
Diaphragm walls are commonly
used in congested areas
The picture above shows a Diaphragm wall excavation.
Diaphragm walls are constructed using the slurry trench
A grab used
Once the excavation
Diaphragm of a panel is complete, a
wall steel reinforcement cage
reinforcement is placed in the center of
& concreting the panel.
Concrete is poured in
operation through one or
more tremie pipes that
extend to the bottom of
The tremie pipes are
extracted as the
concrete rises; however,
the discharge end of the
tremie pipe always
remains embedded in
the fresh concrete.
The finished wall after
Long, slender members that transmit
foundation loads through soil strata of
low bearing capacity to deeper soil or rock
strata having a high bearing capacity.
End bearing piles
End bearing piles are those which
terminate in hard, relatively impenetrable
material such as rock or very dense
sand and gravel.
• Friction piles obtain a greater part of
their carrying capacity by skin friction or
adhesion. This tends to occur when
piles do not reach an impenetrable
stratum but are driven for some
distance into a penetrable soil.
Settlement reducing piles
Settlement reducing piles are
usually incorporated beneath
the central part of a raft
foundation in order to reduce
differential settlement to an
acceptable level. Such piles
act to reinforce the soil
beneath the raft and help to
prevent dishing of the raft
in the centre.
• Structures such as tall chimneys,
transmission towers and jetties can be
subject to large overturning moments
and so piles are often used to resist the
resulting uplift forces at the
foundations. In such cases the resulting
forces are transmitted to the soil along the
embedded length of the pile.
Piles in fill
• Piles that pass through layers of moderately- to poorly-
compacted fill will be affected by negative skin friction,
which produces a downward drag along the pile shaft and
therefore an additional load on the pile. This occurs as the
fill consolidates under its own weight.
TYPES OF PILES
• Steel piles
• Concrete piles
• Timber piles (wood piles)
• Steel piles withstand driving pressure well and
very reliable end bearing members.
• Pipe piles are normally, not necessarily filled with
concrete after driving.
• Strength, relative ease of splicing and economy
are some of the advantages cited in the selection.
• Corrosion (salt, acid, moisture and oxygen) >
restricted use for marine installations.
• Much more resistance against
• Concrete is available in most parts of
the world than steel.
• Concrete piles may be pre-cast or
Pre-cast concrete piles
Formed, cast to specified lengths and shapes and cured at pre
casting stations before driven in to the ground.
Their shape and length are regulated at the prefab site.
Usually came in square, octagonal or circular cross-section.
The diameter and the length of the piles are mostly governed
by handling stresses.
Limited to less than 25 m in length and 0.5 m in diameter.
Some times it is required to cut off and splice to adjust for
different length. Where part of pile is above ground level, the
pile may serve as column.
Cast-In-Place Concrete Piles
• Made at the construction
• Steel shell is grounded to the soil to as container
to allow the concrete filled in it
• Not contribute load capacity to the pile
Timber piles (wood piles)
• Timber piles are frequently used as
cohesion piles and for pilling under
• Made from tree trunks with the branches
and bark removed.
• Normally wood piles are installed by
driving. Typically the pile has a natural taper
with top cross-section of twice or more than
that of the bottom.
• To avoid splitting in the wood, wood piles are
sometimes driven with steel bands tied at
the top or at the bottom end
Can be form of >>>>>>>
When dry conditions prevail, soils consistently lose
moisture and shrink. When moisture levels are high, the
opposite is true, and soils swell
It will most likely manifest itself in the form of visible
cracks in the foundation walls, exterior brick walls, or
interior sheetrock or plaster walls. Officially, any
structure movement is known as differential settlement.
• Poor drainage
• Moisture around the foundation
• Plumbing leaks
• Bad Design
• Faulty Construction
• Extraordinary Loads
Yard and gutter
the base of the
Moisture around the foundation can
cause the soils to become over-
saturated and lose the strength to
support weight. When this happens,
structures “settle” or sink into the
During an active season, roots
extending beneath and around the
footings of the house can remove
moisture from the soil, causing it to
become desiccated. Again, where
expansive soils exist this removal of
moisture will cause soil shrinkage and
• Material used
• Construction workers
• Failure to take into account the loads the
structure will be called upon to carry,
• erroneous theories,
• inaccurate data,
• ignorance of the effects of repeated or
• improper choice of materials or
misunderstanding of their properties.
• The use of salty sand to make
• Bad riveting or even improper
tightening torque of nuts,
• bad welds,
• Extraordinary loads are often natural,
such as repeated heavy snowfalls, or
• the shaking of an earthquake, or
• the winds of a hurricane. A building
that is intended to stand for some
years should be able to meet these
The picture on the right
shows a building which
has lost the ground
This house will
probably have to be
Do New Houses Have Foundation
Unfortunately, for many
homeowners, problems may develop
relatively soon after the house has been
completed. While older homes
experience some settling over time,
serious foundation failures occur more
frequently in homes less than ten years
When the ground shakes,
lose particles (i.e. soil)
moves in a fashion similar
to a liquid (i.e. water).
When the soil (which is
lose) surrounding it is
shaken the foundation in
effect sinks. This is often
uneven and the building
Doors that won't close
The problem occurs when only part of the
foundation heaves or settles, causing cracks and
other damage. This differential movement is
largely caused by differences in soil moisture.
Settlement cracks are nearly always vertical.
Exterior Warning Signs :
Separation around garage door, windows and/or
Broken and/or cracked foundation
Interior Warning Signs
Misaligned Doors and Windows
Cracks in Floor
Misaligned Doors and Windows