Prefabricated structures

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PRE FABRICATED
MODULAR STRUCTURES
GUIDED BY:
SOUMYA MISS
ASST PROFFESSOR,
UKFCET, KOLLAM
PRESENTED BY:
FAIZAL.A.M
7TH SEMESTER
CIVIL ENGINEERING
UKFCET, KOLLAM

Contents
 Introduction
 Features
 Comparison
 Design concept
 Components
 Types of precast
system
 Design
consideration
 Equipments
 Assembling
 scheduling
 Advantages
 Limitations
 Conclusion
 references
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Introduction
 The concept of precast structures also known
as prefabricated/ modular structures.
 The structural components are standardized
and produced in plants in a location away
from the building site.
 Then transported to the site for assembly.
 The 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.
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Features
 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.
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Comparison
Site-cast
 no transportation
 the size limitation is
depending on the
elevation capacity only
 lower quality because
directly affected by
weather
 proper, large free space
required
Precast at plant
 transportation and
elevation capacity limits
the size-
 higher, industrialized
quality – less affected by
weather
 no space requirement on
the site for fabrication
 unlimited opportunities of
architectural appearance
 option of standardized
components
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Design concept for precast
concrete buildings
 The design
concept of
the precast
buildings is
based on
 1.build
ability.
 2.economy
3.standardiz
ation of
precast
components.
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Precast concrete structural
elements
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Precast slabs
Precast Beam & Girders

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Precast Columns
Precast Walls

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Precast stairs
Precast concrete Stairs
Steel plates supported on 2 steel
beams

Design considerations
 final position and loads
 transportation requirements – self load and
position during transportation
 storing requirements – self load and position
during storing – (avoid or store in the same
position as it transported / built in)
 lifting loads – distribution of lifting points –
optimal way of lifting (selection of lifting and
rigging tools)
 vulnerable points (e.g. edges) – reduction of
risk (e.g. rounded edges)
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Types of pre cast system
1. Large-panel systems
2. Frame systems
3. Slab-column systems with walls
4. Mixed systems
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 box-like structure.
 both vertical and
horizontal elements are
load-bearing.
 one-story high wall panels
(cross-wall system /
longitudinal wall system /
two way system).
 one-way or two way
slabs.
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1. Large-panel systems

2. Frame systems
 Components are usually
linear elements.
 The beams are seated
on corbels of the pillars
usually with hinged-
joints (rigid connection
is also an option).
 Joints are filled with
concrete at the site.
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3.Lift-slab systems
 - partially precast in plant
(pillars) / partially precast on-
site (slabs).
 - one or more storey high
pillars (max 5).
 - up to 30 storey high
constructions.
 - special designed joints and
temporary joints.
 -slabs are casted on the
ground (one on top of the
other) – then lifted with crane
or special elevators.
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Lift-slab procedure
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1. pillars and the first package (e.g. 5 pieces) of slabs
prepared at ground level
2. lifting boxes are mounted on the pillars + a single slab
lifted to the first floor level
3-8. boxes are sequentially raised to higher positions to
enable the slabs to be lifted to their required
final position - slabs are held in a relative (temporary)
positions by a pinning system

Planning traffic route
 How long transporter
vehicle is required?
 What is the required
load capacity of the
transporter vehicle?
 What is the maximum
vertical extension of the
shipment
 Routs on the site
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• Is route permission
required?

Equipments
cranes:
 mobile crane
 tower crane (above
3stories)
lifting tools:
 spreader beams
 wire rope slings
rigging tools:
 eye bolt
 shakles
 hooks
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Assembling….
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Column to column connection

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Precast concrete structure consisting of
solid wall panels and hollow core slabs.
Wall to slab connection

Advantages
 Quick erection times
 Possibility of conversion, disassembling
and moving to another site
 Possibility of erection in areas where a
traditional construction practice is not
possible or difficult
 Low labor intensivity
 Reduce wastage of materials
 Easier management of construction sites
 Better overall construction quality
 Ideal fit for simple and complex structures
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Limitations
 size of the units.
 location of window openings has a
limited variety.
 joint details are predefined.
 site access and storage capacity.
 require high quality control.
 enable interaction between design
phase and production planning.
 difficult to handling & transporting.
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Scheduling
some approximate data for installation
 emplacement of hollow core floor slabs -
300 m2/day
 erection of pillars/columns - 8 pieces/day
 emplacement of beams - 15 pieces/day
 emplacement of double tee slabs - 25
pieces/day
 emplacement of walls - 15 pieces/day
 construction of stair and elevator shafts -
2 floors/day
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Examples….
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The hospital will feature multi-trade prefabricated racks in the corridors, an
approach that is still new in the U.S.

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Miami Valley Hospital Dayton,OH

Conclusion
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oThe use of prefabrication and preassembly is
estimated to have almost doubled in the last 15
years, increasing by 86%.
oThe use of precast concrete construction can
significantly reduce the amount of construction waste
generated on construction sites.
o Reduce adverse environmental impact on sites.
o Enhance quality control of concreting work.
o Reduce the amount of site labour.
o Increase worker safety .
o Other impediments to prefabrication and
preassembly are increased transportation
difficulties, greater inflexibility, and more advanced
procurement requirements.

References
 [1] Szőnyi L.: Construction of prefabricated reinforced concrete
buildings, 2011
 [2] Benett, D.: Concrete Elegance 2004. Concrete Centre, 2005
 [3] Precast Concrete Structures. www.paradigm.in 2012.10.10
 [4] S. Brzev, T. Guevara-Perez: Precast Concrete Construction.
http://business.management6.com/PRECAST-CONCRETE-
CONSTRUCTION-pdfe13174.
 [5] Sonjoy Deb: Precast Concrete for Building
Systemshttp://masterbuilder.co.in/Archives/Building%20Material
s/Concrete/Precast%20
Concrete%20for%20Building%20Systems.pdf 2012.10.10
 [6] Lift slab
systemhttp://webs.demasiado.com/forjados/patologia/lift_slab/as
pect/index.htm2012.10.23
 [7] http://www.liftplanner.net/steamdrum.html 2012.10.23
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Prefabricated structures

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