Description of precast universe in the construction field. (Emerging methodologies in the field of construction)

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2. PRESENTED BY:-
NAME: GEDALA JAIRAM
BRANCH: CIVIL ENGINEERING
6th SEMESTER
REGD. NO. : F13011001012
GUIDED BY:-
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Er. MALBIKA PATRA

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INTRODUCTION
 PRECAST VS CAST IN-SITU
TYPES OF PRECAST CONSTRUCTION
ELEMENTS IN PRECAST CONSTRUCTION
CONNECTIONS IN PRECAST CONSTRUCTION
BENEFITS OF PRECAST CONSTRUCTION
DISADVANTAGES OF PRECAST CONSTRUCTION
 MARKETING OF PRECAST CONSTRUCTION
CONCLUSION

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5. TRANSPORTATION COMMUNICATION
DIESEL ENGINE TRAIN
VS
BULLET TRAIN
KEYPAD MOBILE
VS
TOUCH SCREEN
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6. CAST IN-SITU VS PRECAST
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Precast concrete is a construction product produced by casting concrete in a
reusable mold or "form" which is then cured in a controlled environment, transported
to the construction site and lifted into place. In contrast, standard concrete is poured
into site-specific forms and cured on site. Precast stone is distinguished from precast
concrete by using a fine aggregate in the mixture, so the final product approaches the
appearance of naturally occurring rock or stone.
Ancient Roman builders made use of concrete and soon poured the material into moulds
to build their complex network of aqueducts, culverts, and tunnels. Modern uses for pre-
cast technology include a variety of architectural and structural applications featuring
parts of or an entire building system. In the modern world, precast panelled buildings
were pioneered in Liverpool, Engl and, in 1905. A process was invented by city
engineer John Alexander Brodie, whose inventive genius also had him inventing the
football goal net. The tram stables at Walton in Liverpool followed in 1906. The idea was
not taken up extensively in Britain. However, it was adopted all over the world,
particularly in Eastern Europe] and Scandinavia.
In the US, precast concrete has evolved as two sub-industries, each represented by a major
association. The Precast Concrete Products industry focuses on utility, underground, and
other non-prestressed products, and is represented primarily by the National Precast
Concrete Association (NPCA). The Precast Concrete Structures industry focuses on
prestressed concrete elements and on other precast concrete elements used in above-
ground structures such as buildings, parking structures, and bridges. This industry is
represented primarily by of the Precast/Prestressed Concrete Institute (PCI).

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 The concept of precast (also known as “prefabricated”) construction includes
those buildings, where the majority of structural components are standardized and
produced in plants in a location away from the building, and then transported to the
site for assembly.
 These components are manufactured by industrial methods based on mass
production in order to build a large number of buildings in a short time at low cost.
 The main features of this construction process are as follows:
 The division and specialization of the human workforce .
 The use of tools, machinery, and other equipment, usually automated, in the
production of standard, interchangeable parts and products .
 Compared to site-cast concrete, precast concrete erection is faster and less affected
by adverse weather conditions.
Plant casting allows increased efficiency, high quality control and greater control on
finishes.
This type of construction requires a restructuring of entire conventional
construction process to enable interaction between design phase and production
planning in order to improve and speed up construction.

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TIME
MONEY
LABOUR

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 Large-panel systems
 Frame systems
 Slab-column systems with walls
 Depending on the load-bearing structure, precast systems
can be divided into the following categories:

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The designation “large-panel system” refers to multistory structures composed
of large wall and floor concrete panels connected in the vertical and horizontal
directions so that the wall panels enclose appropriate spaces for the rooms
within a building. These panels form a box-like structure. Both vertical and
horizontal panels resist gravity load. Wall panels are usually one story high.
Horizontal floor and roof panels span either as one-way or two-way slabs.
When properly joined together, these horizontal elements act as diaphragms
that transfer the lateral loads to the walls.
 Large-panel systems
Depending on wall layout , there are three basic
configurations of large-panel buildings:
• Cross-wall systems
• Longitudinal wall systems
• Two-way systems

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Precast frames can be constructed using either linear elements or spatial
beam column sub-assemblages. Precast beam-column sub-assemblages have
the advantage that the connecting faces between the sub-assemblages can
be placed away from the critical frame regions; however, linear elements are
generally preferred because of the difficulties associated with forming,
handling, and erecting spatial elements.
 Frame systems
The use of linear elements generally
means placing the connecting faces at the
beam-column junctions. The beams can
be seated on corbels at the columns, for
ease of construction and to aid the shear
transfer from the beam to the column.
The beam-column joints accomplished in
this way are hinged. However, rigid beam-
column connections are used in some
cases, when the continuity of longitudinal
reinforcement through the beam-column
joint needs to be ensured.

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These systems rely on shear walls to sustain lateral load effects, whereas the
slab-column structure resists mainly gravity loads. There are two main
systems in this category:
• Lift-slab system with walls
• Pre-stressed slab-column system
In the Lift –slab system, the load-bearing structure consists of precast
reinforced concrete columns and slabs.
 Slab-column systems with walls
Precast columns are usually two stories high. All
precast structural elements are assembled by means
of special joints. Reinforced concrete slabs are poured
on the ground in forms, one on top of the other.
Precast concrete floor slabs are lifted from the
ground up to the final height by lifting cranes. The
slab panels are lifted to the top of the column and
then moved downwards to the final position.
Temporary supports are used to keep the slabs in the
position until the connection with the columns has
been achieved.

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STAIRCASE FOOTING

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30. WEATHERPROOF PROTECTS AGAINST FIRE
 Precast concrete is resistant
to rain penetration, flood
damage and windblown
debris.
 Precast concrete is fireproof. It
protects against the spread of fire
between rooms or properties, and
it cannot catch fire, burn or drip
molten particles.
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31. WI-FI COMPATIBLE ACOUSTICALLY VERSATILE
 With homes and offices
increasingly wired for
information technology, it is
good news that precast
concrete buildings do not
interfere with radio, local
wi-fi or internet networks.
 Because precast can be formed in
any shape, size and texture, it can
be designed to deflect or absorb
sound.
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32. DURABLE DAMPENS VIBRATION
 Concrete buildings from
hundreds of years ago are still
in use today. Some say
concrete can last up to 2,000
years, and there are certainly
many structures around that
are well on their way to such a
ripe old age.
 Precast concrete can be used to
dampen these vibrations due to its
mass, which makes it the material
of choice for modern stadium and
concert hall construction.
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33. INTELLIGENT
QUALITY IN PRODUCTION
AND CONSTRUCTION
 It may be helpful to know how a
structure is performing over
time. Microchips can be
embedded in precast concrete to
log data on movement or stress.
Engineers then capture the data
on the chip by swiping a reading
device across the surface of the
element.
 Precast products are manufactured
in plants under strictly controlled
conditions. Precast manufacturers
can be teamed with engineers,
specifiers, installers and owners to
guarantee precise and reliable
workmanship.
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34. CAN BE REUSED SUSTAINABLE
 At the end of a structure’s life,
precast products can be
reclaimed as whole elements
such as floor slabs. These could
be reinstalled in the same
building or even transported a
short distance and used in a
comparable structure elsewhere.
 Precast is perfect for today’s focus
on preserving resources and
protecting the environment
through sustainable building
practices.
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 All the workers must be literates and technically educated .

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 If not properly handled, the precast units may be damaged
during transport.

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 It becomes difficult to produce satisfactory connections
between the precast members.

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 It is necessary to arrange for special equipment for lifting
and moving of the precast units.

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 The economy achieved in precast construction is partially
balanced by the amount to be spent in transport and handling of
precast members. It becomes therefore necessary to locate the
precast factory at such a place that transport and handling charges
are brought down to the minimum possible extent.

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