Prefabrication
Name : Isar kotur
USN No :2IG19AT010
Subject : MMBC Sem :7th
INTRODUCTION
•Prefabrication is the practice of 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.
•It is combination of good design with modern high performance components and quality controlled manufacturing
procedures.
•This work is carried out in two stages, manufacturing of components in a place other than final location and their erection in
position.
•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.
•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
ABOUT PREFABRICATION
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
1. Casting.
2. Curing.
3. 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. 6
•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.
•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
Casting
Curing
Transportation and erection.
PREFABRIC BUILDING COMPONENET
• Some of them prefabricated components are as explained
below
• 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 Column to
connections is to ensure continuity and this can be achieved Column Connection
by a variety of methods.
• Beams: - Beams can vary in their complexity of design and
reinforcement from the very simple beam formed over an •Column to Column Connection
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
• A precasting concrete haunch is cast on to the column 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.
•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 18
GLANCE AT BUILDING
PROCESS
SLAB TO BEAM CONNECTION
•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.
•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.
Advantages Disadvantages:
•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
•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.
