Building Component and Structures

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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-situpiles


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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

Building Component and Structures

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