building component and structures
TRANSCRIPT
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Structure consists of two parts
Sub Structure
Super Structure
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Which is below the Plinth level
Otherwise known as Foundation
Which forms the base for any structure
About 30% of the total construction cost isspent on the foundation
FOUNDATION: Lower part of a structure
which transmits the load, weight of the
superstructure to the subsoil
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Support the structures
Prepare a level surface for Concreting and
Masonry work
Distribute the total load coming on thestructure on a larger area.
Give enough stability to the structures
against various disturbing forces such as wind
and rain.
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Should be designed to take up the future
extension of the building Should provide a level surface for building
operations
Should be stable or safe against any possible
failure Should give stability to the supported
structure
Load should be evenly distributed to
substratum, so that unequal settlement is
prevented
Safety against undermining
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Dead Load
Live Load
Wind Load
Bearing Capacity of Soil:
The ability of the soil to support the loadcoming on it without failure.
It is also known as bearing power of Soil.
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Ultimate Bearing Capacity:
It is the maximum load supported by soil before it
fails
Ultimate load
Ultimate Bearing capacity= ------------------------------
Area
Safe Bearing Capacity:
Maximum pressure a which the soil can carry safely
without risk of shear failure.
Ultimate bearing capacity
Safe Bearing capacity= ------------------------------
Factor of Safety
FOS adopted is 2 to 3.
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By increasing the depth of foundation
By draining the sub soil water By compacting the soil
By confining the soil mass
By cement grouting
By chemical treatment
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Shallow Foundation(Depth < Width)
Deep Foundation (Depth is very large)
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Isolated Column Footing
Simple Footing
Stepped Footing
Sloped Footing
Wall Footing
Combined Footing
Continuous Footing
Cantilever Footing Inverted arch Footing
Raft (or) Mat Foundation
Stepped Foundation
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Provided under the column to transfer the
load safely to the soil bed. If the column loaded is lightly a spread is
given under the base of the column. The
spread is known as Footing.
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Stepped Footing:
For heavy loaded columns the total width of
footing may be very high.
This is attained in three or four steps and is
called stepped footing.
Sloped Footing:
If total width of the footing is attained by
gradually increasing the width towards the
bottom.
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If footing is provided throughout the length
of the wall in the case of load bearing walls. It may be either simple or stepped
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If footing is constructed for two or more
columns
Rectangular or Trapezoidal
In rectangular combined footing the columns
carry equal loads
In trapezoidal combined footing the columncarry unequal loads ,with the outer column
carrying heavier load.
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A single continuous R.C.slab is provided as
foundation for three or more columns in a
row.
It is more suitable to prevent the differential
settlement in the structure
Safety against Earthquake
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Where the distance between the column is so
great It consists of spread footings of two columns
,connected by a strap beam
Strap beam does not remain in contact with
soil, and thus does not transfer any pressure
to the soil
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Constructed between the two walls at the
base
Suitable for low bearing capacity and depth
of the foundation is to be kept less
Bridges,reservoirs,tanks etc
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When the load of the structure is very heavy
and the bearing capacity of soil is very low Load is transmitted to the soil by means of a
continuous slab that covers the entire area
of the bottom of a structure similar to a floor
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When the ground is sloping it becomes
uneconomical to provide foundations at samelevel
Overlap between two layers of foundation
concrete slab is equal to the depth of
concrete slab or two times the height of thestep
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Pile Foundation
Pier foundation
Well or Caisson Foundation
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Based on function (or) Use
End Bearing Piles
Friction Piles
Compaction Piles
Under ream Piles Sheet Piles
Based on materials and Composition
Concrete piles
a)Cast-in-situ piles
(i)Cased cast-in-situ-piles
(ii)Uncased cast-in-situ- piles
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(Continued)
(b) Pre-Cast Concrete Piles
Timber piles Steel piles
(a) H-Pile
(b)Pipe Pile
(c) Sheet Pile
Composite Piles
(a)Concrete and Timber pile
(b)Concrete and Steel Pile
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End Bearing Piles
o Penetrate through the soft soil and their
bottom rest on a hard bed.o These piles acts as columns or piers
o Soft ground through which the piles pass also
give some lateral support to the piles.
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Friction Piles:
o Used to transfer loads to a depth of a friction
load carrying material by means of skin
friction along the length of the piles.
Compaction Piles:
o Used to compact loose granular soils, thus
increasing their bearing capacity.o The compaction piles themselves do not
carry load. Hence may be of weaker
materials.
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Under Ream Piles:
o Piles with one or more bulbs in its vertical
shaft
o These bulbs are known as Under ream
o They increase the bearing capacity of the
pile considerably and also resist the uplift.
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Sheet Piles:
o Thin member of steel or timber is used
o Commonly used as in pervious cut off to
reduce seepage and uplift under hydraulic
structures
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Cast-in-situ piles:
Piles are casted in the site itself.
A bore is dug into the ground by inserting acasting.
After placing reinforcement, this bore is
filled with cement concrete.
If the casing is kept position after placing theconcrete then it is called cased cast-in-situpiles.
If the casing is withdrawn after placing
concrete then it is called uncased cast-in-situ concrete piles.
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Pre Cast Concrete Piles:
Which are manufactures in factory or at a
place away from the construction site, thendriven into ground at the place required.
It may be square, octagonal or round in
shape.
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Timber Piles:
Trunks of trees are used as pile.
Wood should be free from any defect May be circular or square.
Steel Piles:
Rolled steel sections and fabricated sections
are used as pile.
Types: H-Beam, Box ,Tube Piles
Composite Piles:
Made up of two portions of differentmaterials one above the other
Types: Timber and Concrete, Steel and
Concrete
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Pier Foundation:
Consists of a cylindrical column of large
diameter to support the load through bearing
only.
W ll F d ti
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Well Foundation:
Used for foundations under water such as
bridges.
The load is transferred through the wallaround called staining.
The well is constructed and brought to the
site.
Types: Circular,Twin circular,Twinhexagonal,Twin octagonal,Double D, Dumb
well, Rectangular