Construction industry is growing day by day, whereas free space for material is reducing dayby day. Prefabricated structure provide a way through. Prefabrication is method in which structural members are built at industry and then transferred to site.

1. PRE-FABRICATED
STRUCTURES
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2. What We Are Going To Learn
• What is mean by Prefabricated structure?
• Concept of prefabricated structure.
• Prefabrication & its components.
• Advantage and disadvantage of prefabrication.

3. What is prefabrication?
• Assembling components of a structure in
a factory or other manufacturing site,
and transporting complete assemblies or sub-
assemblies to the construction site where the
structure is to be located.
• The work is carried out in two stages,
manufacturing of components in a place other
than final location and their erection in position.
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4. Stages of pre fabrication
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• The Prefabrication as defined will be done in
two stages
• Manufacturing at factory condition and erection
of components at the required location.
• This requires certain stages of preparation.
They are
Casting.
Curing.
Transportation and erection.

5. Casting
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• Precast components are casted with controlled
cement concrete in moulds of required shape
and sizes.
• The vibrator is used to vibrate concrete and
this removes any honeycombing inside the
components.

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7. Curing
• After 24 hours of casting, the casted components
are released from the mould and transported to
curing tanks.
• Certain special components like railway sleepers
where high strength is required are steam cured.
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9. Transportation and erection
• After complete curing is done the components
are transported to the site with heavy trucks and
erection will be done using cranes with skilled
labour force.

11. Prefab building components
Columns:
• A column is a vertical member carrying the beam and
floor loadings to the foundation.
• It is a compression member and therefore the column
connection is required to be proper.
• The main principle involved in making column
connections is to ensure continuity and this can be
achieved by a variety of methods. 11

12. Column to Column Connection

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Beams: -
• Beams can vary in their complexity of design and
reinforcement from the very simple beam formed
over an isolated opening to the more common
encountered in frames where the beams transfer
their loadings to the column.
• Column and beam reinforcement, generally in the
form of hooks, are left exposed. The two members
are hooked together and covered with insitu concrete
to complete the joint.

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Waffle unit for flooring / roofing: -
• These are suitable for roofs / floors spanning in
two directions.
• They are laid in a grid pattern.
• These units are cast in moulds.
• The saving achieved is not much. Also Shuttering
are complicated and costly.
• Time consumption for construction is less

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SLAB TO BEAM CONNECTION

18. Advantages
• Saving in cost, material, time & manpower.
• Shuttering and scaffolding is not necessary.
• Installation of building services and finishes can
be done immediately.
• Independent of weather condition.
• Components produced at close supervision .so
quality is good
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19. Disadvantages
• Handling and transportation may cause breakages of
members during the transit and extra provision is to
be made.
• Difficulty in connecting precast units so as to produce
same effect as monolithic. This leads to non-
monolithic construction.
• They are to be exactly placed in position, otherwise
the loads coming on them are likely to get changed
and the member may be affected. 19

20. This Presentation is Brought to you
by
An Civil Engineering Blog