PRBAFABRICATED
STRDCTURES
PRESENHED BY:
R DVYA VISHNOI
ASSSTANE PRORESSOR
CVLENGG DEPER P
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CONTENTS
INTRODUCTION.
PREFABRIC CONCEPT.
>
PREFABRICATION.
PREFABRIC COMPONENTS.
ADVANTAGES AND DISADVANTAGES.
CONCLUSIONS.
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INTRODUCTION
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PREFABRICATIONCONCEPT
What is prefabrication?
Prefabrication is the practice of assembling components
of a structure in a factory or other manufacturing site,
and transporting complete assemblies or sub-ašsemblies to
the construction site where the structure is to be located.
a
It is combination of good design with modern high
performance compoents and quality controlled
manufacturing procedures.
Thiswork is çarried out in two stages, manufacturing of
components in a place other than inal location and their
erection in position.
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PREFABRICATION CONCEPT
Prefabricated sections are produced in large quantities in a
factory and then shipped to various construction sites.
This procedure may allow work to continue despite poor
weather conditions and should reduce any waste in time
and material at the site.
o
Precast concrete units are cast and hardened before being
used for construction
Sometimes builders cast components at the building site
and hoist them into place after they harden.
This technique permits the speedy erection of structures.
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PRE FABRICATION
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.
Casting: - 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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PRE FABRICATION
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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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PRE FABRICATION
a
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.
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PRE FABRICATION
For Indian conditions partial prefabrication is well
suited.
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PREFABBUILDING
COMPONENTS
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PREFAB BUILDING
COMPONENTS
Some of the prefabricated components are as explained
below
Columns: - A column is a vertical member carrying the
beam andfloor loadings to the foundation.
It is a compression member and therefore the column
connection is required to be proper.
a
The main principle involved in making column
connections is to ensure continuity and this can be
achieved by a variety of methods.
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Shirre
Tbe sotire
drp-peched
ater
aignet
Belre Asebiy Assenbsed Grouted
Column toColumn Connection 15
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PREFAB BUILDING
COMPONENTS
Beams: - Beams can vary in their complexity of design and
reinforcementfrom 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.
Methods of connecting beams and columns are
precasting concrete haunch is cast on to the column
A
with a locating dowel or stud bolt to fix the beam.
A
projecting metal corbel is fixed to the column and the
beam is bolted to the corbel.
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.
This is as shown in the figure.
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column connection BEAM TO COLUMN CONNECTION Page 16 of 29
bearing plate
precast concrete
column projecting tie bars
for floor units
"U' bolt cast into
column for edge
beam connection -Colaose tre
nut and washer
recess
tie
bars
p.c.c. edge coisYs
dowel
beam rebated
to provide
bearing for cross beam recessed
reinforced at end to receive tie
floor units haunch bars and location dowel
NB beam recess filled with cement grout to complete connection
p.c.c. rebated edge beam
p.c.c. column
bearing plate
bolted to bracket
tie bars for
floor units
connection Adcod
completed with
in situ concrete
angle bracket -Bnidoraog -Bang padr
bolted to column alternative 'tee' bars
cast into column and
bolted to projecting
plate cast into beam
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PREFAB BUILDING COMPONENTS
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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50 mm thick in situ topping Page 18 of 29
reinforced with welded fabric
R.C. edge beam
in situ ribs
at 800 c/c
Typical waffle
floor mould
plan size 800 x 800
depths 225, 300 & 375
honeycomb
indents left rib reinforcement
by moulds to design
Linsitu ribs at 800 c/e
R.C. edge beam
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Untopped hollow-core slab
Grout
Welded agle
contedor
Reinforcing bar ties are
grouted into keysbetween
slab elements
Bearing pad
SLABTO BEAM CONNECTION
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GLANCE AT BUILDINGPROCESS
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ADVANTAGES AND
DISADVANTAGES
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ADVANTAGES AND DISADVANTAGES
Advantages:
Saving in cost, material, time & manpower.
Shuttering and scaffolding is not necessary.
Installationof building services andfinishes can be done
immediately.
Independent of weather condition.
Components produced atclose supervision .so quality is
good
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ADVANTAGES AND DISADVANTAGES
Advantages:
Clean and dry work at site.
Possibility of alterations and reuse
Correct shape and dimensions and sharp edges are
maintained.
Very thin sections can be entirely precast with precision.
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ADVANTAGESAND DISADVANTAGES
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.
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ADVANTAGES AND
DISADVANTAGES
Disadvantages:
High transport cost
Need of erection equipment
Skilled labour andsupervision is required.
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CONCLUSION
The prefab components and prefab structures eliminate
space and time over conventional constructions.
Although prefabrication is employed to a large extent in
a wide variety of countries, in India, construction
industry, in spite of its expansion continues to adopt
same conventional methods.
The root of the economic problem is the fact that the
majority of the households do not have the confidence
needed to construct prefab houses.
be
These structures are easy to erect as it is light material.
This type of prefab buildings were constructed in
earthquake prone areas of Lature and Gujarat.
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REFERENCES
Google.com
Britanica.com
www.dictionaryofconstruction.com
bkaviani. wordpress.com
www.concrete.org.uk
- IE (I) Journal-AR
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THANK YOU
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