Prefabricated structures

BY:
VASUNDHRA SINGH
AISHWARYA DEOPUJARI
SRIDEVI
NISHTHA DUGGAL
PRERANA DAS
NAKUL SHARMA
SECTION - B
1
B.M.C.T – VII
PRE FABRICATED
MODULAR STRUCTURES

CONTENTS
 Introduction
 Features
 Comparison
 Design concept
 Components
 Types of precast system
 Design consideration
 Equipments
 Assembling
 scheduling
 Advantages
 Limitations
 Conclusion
 references
2

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.
3

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.
4

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
5

DESIGN CONCEPT FOR PRECAST CONCRETE
BUILDINGS
• The design concept of
the precast buildings
is based on
• 1.build ability.
• 2.economy
3.standardization
of precast
components.
6

PRECAST CONCRETE STRUCTURAL ELEMENTS
7
Precast slabs
Precast Beam & Girders

8
Precast Columns
Precast Walls

9
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)
10

TYPES OF PRE CAST SYSTEM
1. Large-panel systems
2. Frame systems
3. Slab-column systems with walls
4. Mixed systems
11

• 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.
12
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.
13

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.
14

LIFT-SLAB PROCEDURE
15
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

EQUIPMENTS
cranes:
• mobile crane
• tower crane (above
3stories)
lifting tools:
• spreader beams
• wire rope slings
rigging tools:
• eye bolt
• shakles
• hooks
16

ASSEMBLING
17
Column to column connection

20
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
21

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.
22

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
23

CONCLUSION
24
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%20Mater
ials/Concrete/Precast%20
Concrete%20for%20Building%20Systems.pdf 2012.10.10
• [6] Lift slab
systemhttp://webs.demasiado.com/forjados/patologia/lift_slab
/aspect/index.htm2012.10.23
• [7] http://www.liftplanner.net/steamdrum.html 2012.10.23
25

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