Reports on Precast System

1
A
MAJOR PROJECT REPORT
ON
PREFABRICATED RCC STRUCTURES
SUBMITTED IN THE PARTIAL FULFILLMENT OF THE REQUIREMENT
FOR THE AWARD OF DEGREE
OF
BACHELOR OF TECHNOLOGY
IN
CIVIL ENGINEERING
SUBMITTED TO: SUBMITTED BY:
DEPARTMENT OF CIVIL ENGINEERING SHER BAHADUR BUDHA (4914768)
NAVIN ACHARYA (4914756)
GYANENDRA SAH (4914754)
SHARWAN ADHIKARY (4914727)
PANKAJ DALIYA (4915817)
SHAMBHU YADAV (4914434)
DEPARTMENT OF CIVIL ENGINEERING
GEETA ENGINEERING COLLEGE, PANIPAT
BATCH 2014-2018

2
This is to certify that the minor project report on “PREFABRICATED RCC STRUCTURES
” which is submitted by Sher Bahadur Budha (4914768), Navin Acharya (4914756), Gyanendra
Sah (4914754), Sharwan Adhikari (4914727) and Pankaj Daliya (4915817) for partial fulfillment
for the award of degree of Bachelor of Technology in Civil Engineering to Geeta Engineering
College, Panipat. It is record of student’s own work carried by them under my supervision and
guidance during academic session 2014-2018. This work is approved for submission.
Supervisor:
Mr.Sravjeet Singh
Date: Assistant Professor
Place: Panipat

3
ACKNOWLEDGEMENT
This project work would not have been possible without the guidance and help of
several hands who in one way or another contributed and extended their valuable
assistance in the preparation and completion of this report. It is our privilege to
extend our heartfelt gratitude and indebtedness to our supervisors, Mr. Sravjeet
Singh, Mr. Aman Bathla and Mr. Ujjwal Goel, Assistant professor, Department of
Civil Engineering, Geeta Engineering College, Naultha, Panipat, Haryana, for their
guidance in providing the visual inputs and seeing the major project report work
through to completion. We wish to thank them for their invaluable insight and wise
counsel during every stage of project work for their attention to the important details
in writing process. We also extend our deep thanks to Mr. Manjeet Ghangas
(HOD), Department of Civil Engineering, Geeta Engineering College, for his
immense concern throughout the project work and for providing us the laboratory
facilities. We extend warm thanks to Mr. Anand Sir& Mrs. Jyoti mam, Assistant
Professor, Department of Civil Engineering, Geeta Engineering College, providing
for moral support throughout the project work. A special thanks to Dr.B.S. Chahal
Sir Professor of Department of Civil Engineering, Geeta Engineering College, who
motivated to achieve our goal & enlightened us with the touch of his knowledge &
constant encouragement. It also gives great pleasure to express our gratitude
towards Mr. Deepak Sir (lab in-charge). The words are insufficient to express our
feelings & we feel incomplete without the company of friends & batch mates, who
always give us moral support and help where ever we needed. We shall ever remain
thankfully indebted to all those learnt souls, our teachers, friends, teaching & non-
teaching staff, known and unknown hands who motivated to achieve our goal &
enlightened us with the touch of their knowledge & constant encouragement. We
are really grateful for the help rendered by all faculty of Civil Engineering
Department at GEC, Panipat (Haryana) who were always there for making us
understand the minor details of the work. Finally, we wish to extend a warm thanks
to everybody involved directly or indirectly with our work. The whole credit of our
achievements goes to our parents and our friends who were always there for us in
our difficulties. It was their unshakable faith in us that has always helped us to
proceed further

4
TABLE OF CONTENTS
Chapters Page no.
1. Introduction 9
2. Principles: (Aims) 10
3. Needs for prefabrication 10
4. Features 11
5. Comparison 12
6. Prefab materials available in market 13
6.1 Structural Insulated Panels 13
6.2 Insulating Concrete Forms 13
6.3 Color Coated Galvalume Sheets 14
6.4 Zincalume Steel 15
6.5 Colorbond Steel 15
6.6 PUF Panel 16
6.7 Sandwich Panel 17
6.8 Aerocon Panels 17
6.9 FRP Corrugated Sheets 18
7. Design concept of precast system 20
8. Types Of Precast system 22
8.1 Large panel system 23
8.2 Framed System 23
8.3 Slab column system with shear wall 23
8.4 Mixed systems 24
9. Precast structural element 25
9.1 Foundation 25
9.2 Columns 25
9.3 Beams 25
9.4 Slabs 26
9.5 Precast wall 27

5
9.6 Concrete precast stair 28
9.7 In-fill Terrace Units precast bearing façade panels 29
10. Stages of precast concrete block 30
11. Typical connection of precast concrete elements 33
11.1 Column to column Connection 35
11.2 Beam to column connections 35
11.3 Beam to slab joint 36
11.4 Wall to slab connection 36
11.5 Slab to slab connections 37
11.6 Panel to panel connections 38
11.7 Column to foundation connections 39
12. Connection details 39
13. Location of joints 41
14. Recommendation for the erection 43
15. Design consideration 44
16. Equipments 46
16.1 Cranes 47
16.2 Lifting tools 48
16.3 Rigging tools 49
17. Cost benefits analysis 50
17.1 Cost of Construction of Conventional Structures in Railway 50
17.2 Cost of Construction using Prefab Structures 51
18. Advantages, disadvantages & limitation 57
18.1 Advantages 57
18.2 Disadvantages and Limitations 58
19. Conclusion 59

6
LIST OF FIGURES
Name of Figures Page no.
1. Prefabricated building 11
2. Structural Insulated panels 13
3. Insulating concrete farms 14
4. Color coated Galvalume sheets 15
5. Colorbound steel sheets 16
6. PUF panels 16
7. Sandwich panels 17
8. AEROCON panels 18
9. FRP corrugated sheets 19
10. Exploded view I 20
11. Exploded view II 21
12. Exploded view III 21
13. Large panel system 22
14. Framed system 23
15. Mixed system 24
16. Foundation of prefabricated structure 25
17. Columns 26
18. Beams 27
19. Precast slab 28
20. Precast wall 29
21. Concrete precast stairs 30
22. In-fill terrance units 31
23. Precast non-load bearing panels 32
24. Column to column connection 35
25. Beam to column connection 36
26. Wall to slab connection 37
27. Slab to slab connection 38
28. Panel to panel connection 39

7
29. Column to foundation connection 40
30. Cranes 47
31. Spreaders beams 48
32. Wire rope stings 48
33. Eye bolts 49
34. Shakles 49
35. Hooks 49

8
ABSTRACT
This project deals with the prefabrication techniques for residential building using
a system of precast units for columns, beams, roof and walls. Precast R.C.C. planks
and partially Precast R.C. joists are considered for flooring/roofing system in this
paper and special types of precast wall panels are recommended. Prefabricated
columns with a specific configuration, beams and staircase units are considered in
this paper. Special emphasis has been made with respect to the various joints and
connections and the details of these are discussed. A comparison of the cost of
construction of precast system with that of a conventional construction unit has also
been made. Finally, identified that large scale adopting of such a precast systems
will eventually result in considerable cost reduction with the added advantages of
execution speed.

9
CHAPTER I
INTRODUCTION
PREFABRICATION
Prefab is related to prefabricated construction. The word "Prefab" is not an industry
term like modular homes, manufactured homes, panelized home, or site-built home.
The term is an amalgamation of panelized and modular building systems which is
well planned & designed before the initiation of construction and placement of
structure as per detailed design at work site. In industry these are called Pre
Engineered Building (PEB). Prefabricated homes and modular homes are dwellings
manufactured in a factory in advance, usually in sections that can be easily
transported to the site and integrated. Prefabs are made of composite materials
which are manufactured by combination of materials containing different properties
such as plastics, concrete and steel. These are specifically designed for longer
period of applications or usage.
Pre Engineered Buildings (PEBs) are extremely durable, weather as well as termite
proof. Due to their longer life of utility and affordable cost, manufactured homes
can be used for permanent, semi-permanent or temporary applications.
Prefabrication is the practice of assembling components of a structure in a factory
or other manufacturing site and transporting complete assembles to the construction
site where the structure is to be located. Prefabricated building is the completely
assembled and erected building of which the structural parts consist of prefabricated
individual units or assemblies using ordinary or controlled materials.
Prefabricated construction is a new technique and is desirable for large scale
housing programmes.

10
CHAPTER 2
PRINCIPLES: (AIMS)
1. To effect economy in cost
2. To improve in quality as the components can be manufactured under controlled
conditions.
3. To speed up construction since no curing is necessary.
4. To use locally available materials with required characteristics.
5. Workability, thermal insulation and combustibility etc.
CHAPTER 3
NEED FOR PREFABRICATION
Prefabricated structures are used for sites which are not suitable for normal
construction method such as hilly region and also when normal construction
materials are not easily available.
PFS facilities can also be created at near a site as is done to make concrete blocks
used in plane of conventional knick.
Structures which are used repeatedly and can be standardized such as mass housing
storage sheds, go downs, shelter, bus stand security cabins, site offices, fool over
bridges road bridges. Tubular structures, concrete building blocks etc., are
prefabricated structures

11
CHAPTER 4
FEATURES
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.
Fig.1 Prefabricated building

12
CHAPTER 5
COMPARISION
5.1 PREFAB VS CONVENTIONAL STRUCTURE
 Prefab structures are designed lighter section in comparison to conventional
structure.
 Prefab structures are fabricated in workshop which reduces the required
construction time. However, in case of conventional structure there is no
precise control over construction time.
 In prefab structure there is more accuracy in construction as the fabrication
of the structure is done in workshop by the skilled worker as per approved
quality assurance plan (QAP). However in case of conventional building,
there is not much control over accuracy as the same is done by skilled/ semi
skilled workers at site.
 In case of prefab structures, cost is analyzed at the stage of design itself and
therefore chances of fluctuation of cost are very less. However the
construction cost of conventional structure depends upon time and market
fluctuations.
 In the PEBs, ready-made components are used, so the need for formwork,
shuttering and scaffolding is greatly reduced. However in conventional
construction, building components constructed at site requiring formwork,
shuttering and scaffolding. There is minimal effect of climatic or weather
conditions in case of PEBs while in conventional construction, time spent
due to bad weather or hazardous environments at the construction site
increases the construction cost and project completion time.
 In the PEBs, fabrication unit can be located where skilled labour is readily
available and costs of labour, power, materials, space and overheads are
lower. However in conventional construction, construction cost depends
upon location, zone, climatic condition & availability of material & man
power.

13
CHAPTER 6
PREFAB MATERIALS AVAILABLE IN MARKET
6.1 Structural Insulated Panels:
These are composite building material consisting of an insulating layer of rigid
polymer foam sandwiched between two layers of structural board. One of the main
advantages of SIPs is their insulating value, which depends on the thickness of the
foam core. The foam core forms a continuous energy barrier, and the smaller
number of studs leaves less opportunity for heat conduction. One of the biggest
concerns about SIPs is their resistance to insects. While the EPS foam core provides
no nutrition to insects, it offers an easy way for them to tunnel into the structure.
Borate additives can be mixed into the foam during manufacture, providing some
amount of insect resistance.
Fig2. Structural Insulated Panels
6.2 Insulating Concrete Forms:
It is a system of formwork for RCC that stays in place as a permanent interior and
exterior for walls, floors, and roofs. These are interlocking modular units that are
filled with concrete. ICFs are really a hybrid prefab material, since installing rebar
and pouring concrete is done on-site, they offer many of the cost and environmental
benefits of pure prefab.

14
Compared with traditional concrete construction, it is faster to stack ICF foam
blocks than to build a wood form, and since the foam blocks are not removed, there
is much less waste. ICFs provide much better thermal insulation than conventional
framed construction.
Since the wall is solid, there is no possibility of convection within the wall. Sound
transmission is also much lower than conventional frame walls with fiberglass
insulation. One of the disadvantages of ICFs is the potential for improper
installation due to problems with the concrete. The concrete must be fluid enough
to fill the foam blocks without leaving air pockets, which would severely detract
from the structural integrity of the finished wall, yet must be solid enough not to
exert too much horizontal pressure on the foam, which can cause the forms to fail.
Fig3. Insulating Concrete Forms
6.3 Color Coated Galvalume Sheets:
These sheets are preferred material for roofing and wall cladding. They combine
the strength of steel and corrosion protection of zinc or zinc/aluminum alloy
coatings. These are available in various colors, have appealing aesthetics, long life,
durability and easy installation.
Color coated Galvalume sheets of AZ150 class (aluminum zinc coating of 150
grams per sq. meter) with coated alloy of 55% Aluminum, 43.5% Zinc and 1.5%
Silicon and of approved color with top surface coated with 20-25 microns of

15
polyester coating and bottom service coat with 5-10 microns over and above epoxy
primer, basic steel conforming to IS -513, ASTM A 792 M / AS 1397 –
GALVALUME COATING, ASTM A 924 for mechanical properties and ASTM
755 for paint coating.
Overall width of 1120 mm and laid width of 1060 mm, with six crests of 25 mm,
spaced at 206 mm center to center, and with a stiffening rib (28mm) of 3mm height
at the centre of each valley of the sheet, with two anti–capillary grooves with long
return leg on either side of each crest.
Fig4. Color Coated Galvalume Sheets
6.4 ZINCALUME Steel :
This is a product of TATA BlueScope Building materials used for regular and
complicated roll formed roofing, walling, garage door, tubing, gutter, manufactured
goods.
This product is high corrosion resistant and thermal efficient hot dipped zinc-
aluminum alloy (55% Al - Zn) coated steel with spangled surface conforming to AS
1397 available in Grade 300 & 550. Thickness of coating conforms to AZ 150 / AZ
200 (AZ 150 - 55% Al-Zn alloy coating of 150 g/m2 minimum).
6.5 COLORBOND Steel:
This is a product of TATA Bluescope Building materials, pre-painted steel for a
high durable premier roofing, wall cladding, rain water goods and accessories.
ZINCALUME® substrate conforms to AS 1397 and Paint Coating conforms to
AS/NZS 2728 Type 4. The COLORBOND steel is comprising of ZINCALUMER
steel substrate as base material and coatings of Zn-Al alloy Coating, Conversion
Coating , Universal Corrosion Inhibitive Primer (Nominal 5µm) and Finish Coat
(Nominal 20µm) on the front side and similarly with Backing Coat (Nominal 5µm)
on the back side.

16
Fig5. COLORBOND Steel
6.6 PUF Panel:
It is Polyurethane foam, a combination of elastomer and plastic having superior
insulation properties besides other properties such as crack bridging, chemical
resistant, weather tightness and low maintenance cost. These panels are available
with cam lock system.
Fig.6 PUF Panel

17
6.7 Sandwich Panel:
These are used for insulation of roofing and walling in the building. It has one or
both side metal Galvalume sheet and PUF insulation in between. These have high
thermal efficiency and significant mechanical strength, which makes it possible to
go for larger spans as well as large partition walls.
Fig.7 Sandwich Panel
6.8 AEROCON Panels :
Aerocon panels are slim, lightweight wall panels that perfectly substitute
plasterboard, plywood, particleboard and brick wall because of their sheer strength.
Their low weight, ductility, fire and moisture-resistance properties make them
hardy survivors of climatic and accidental disasters. Being pre-fabricated, they are
also easy to install and reduce construction time by 80%. Aerocon panels are
certified Green product by Indian Green Building Council.
The Aerocon panels help to conserve natural resources. Fly ash, which is recycled
waste, is utilised in making these panels.
No wood is used in the manufacture of this product and little water is required
during construction. These panels are also poor conductors of heat, therefore
making a building energy-efficient.

18
Aerocon Panels are ideal as walls, partitions, mezzanine flooring, ceilings and
prefab structures for low cost housing. Aerocon Panels are bringing about a
revolution in building construction, making it green, sturdy, quick and cost-
effective. Aerocon panel is a product of M/s HIL Limited (formally Hyderabad
Industries Limited), Hyderabad. Aerocon panels are available in the following
sizes:
Fig. 8 AEROCON Panels
6.9 FRP Corrugated Sheets:
Fibre-reinforced plastic (FRP) (also fibre-reinforced polymer) is a composite
material made of a polymer matrix reinforced with fibres. The fibres are usually
glass, carbon, basalt or asbestos. The polymer is usually an epoxy or a polyester
thermosetting plastic. FRPs are commonly used as roofing material as it is light
weight, strong and resistive to deforming forces. They are usually rust and termite
proof. They have good impact resistance, possess fire retardant properties and
resistant to external weather conditions.

19
Fig.9 FRP Corrugated Sheets
These are normally available in 0.4 mm to 5.0 mm thickness. They are also available
in transparent & opaque varieties. These are extensively used in parking sheds,
shelters warehouses and residential and industrial roofing etc. where weight saving
is an essential criteria.
6.10 Precast concrete frame
Precast concrete frames involve an entire structure being fabricated off-site. In
addition, structural components can be supplied for incorporation into a structure
on-site. Frames can simultaneously achieve both structural and decorative design
requirements - a wide variety of mixes, colours and finishes can be accommodated.

20
CHAPTER 7
DESIGN CONCEPT FOR PRECAST SYSTEM
Based on considerations of buildability, economy and standardisation of precast
components, the structural concept developed consists of:
 Conventional foundations comprising footings, raft slab or piles and pile
caps.
 Cast in-situ first storey, typically reinforced concrete beam and slab system
 . Precast concrete load bearing walls.
 Precast concrete non-load bearing façade panels.
 Precast concrete floor system, either: - Precast concrete beams and precast
slabs (reinforced concrete or prestressed) with a composite in-situ topping or
Precast concrete walls with precast concrete slab system.
Fig. 10 Exploded view I

21
Fig. 11 Exploded view II
Fig. 12 Exploded view III

22
CHAPTER 8
TYPE OF PRECAST SYSTEM
Depending on the load-bearing structure, precast systems can be divided into the
following categories:
 Large-panel systems
 Frame systems
 Slab-column systems with walls
 Mixed systems
8.1 Large Panel System:
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.
Fig.13 Large Panel System
Depending on wall layout, there are three basic configurations of large-panel
buildings:
 Cross-wall systems
 Longitudinal wall systems
 Two-way systems

23
8.2 Framed System:
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. 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. The
components of a precast reinforced concrete frame are shown in Figure
Fig.14 Framed System
8.3 Slab column system with shear wall
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
• Prestressed slab-column system In the Lift .
slab system, the load-bearing structure consists of precast reinforced concrete
columns and slabs,. Precast columns are usually two stories high. All precast
structural elements are assembled by means of special joints. Reinforced concrete

24
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.
8.4 Mixed systems:
They are compatible with various types of building architecture and they can be
used both for new constructions and for renovations.ARVAL is often cited as a
prime example in all spheres of construction in France and abroad, thus confirming
their rating as leader. Full technical assistance, advice on technical reports, design
notes, as well as the Cofra 4 software sent on request, reinforce this position. Today,
we can see there are three types of slabs that use steel floor profiles : composite
floors, formwork floors and prefabricated composite floors.
The mixed system is also used in precast system as in figure:
Fig.15 Mixed systems

25
CHAPTER 9
PRECAST STRUCTURAL ELEMENT
9.1 FOUNDATIONS
The foundation loads for the precast structural system will be similar to those for
conventional design. However, the arrangement of the foundations below the load
bearing walls will be different to those normally adopted for a column and beam
structural system. The desirable arrangement should provide a relatively uniform
support along the length of the wall and minimize the eccentricity effects due to any
possible misalignment of the walls relative to the foundations.
In the case of a footing foundation system, the recommended solution is a
continuous strip footing below the load bearing walls, as shown in Figure.
Fig.16 Foundation of prefabricated structure
9.2 COLUMNS
Columns are available in a range of shapes, sizes and finishes, can be circular or
square and are designed to incorporate any additional features or fittings. Single
story columns are generally 2.5m - 4m high. Beams bear directly on top of these
units with a dowelled connection between them.
Multi story columns are cast with corbels or alternative connections at locations to
suit the beams at intermediate levels. Projecting rebar can be provided for tying in
to in situ floors. Options for foundation connections include cast in base plates,
dowel tubes or projecting bars.

26
Fig.17 COLUMNS
9.3 BEAMS
The cross-sections of a precast concrete beam will depend on its location within a
structure, its purpose and how it is connected to other members. The simplest will
be rectangular, probably with reinforcement links projecting out of the top around
which in situ concrete can be cast.
Alternatively, beams may have projections, on one or both sides to support
secondary members, such as floor slabs or staircases, or to carry brickwork or
cladding. The beams will be provided with recesses at the ends that fit over corbels
or steel sections projecting from the columns.

27
Fig.18 BEAMS
9.4 PRECAST SLABS:
Precasting is a process in which the slabs are casted under controlled factory
conditions (i.e., not at the exact site of construction).
This precast slab is assembled at the site of construction with other structural
members such as beams and columns.

28
Fig.19 PRECAST SLABS
9.5 PRECAST WALL:
Aesthetics, cost and speed of installation – pick any two. That’s the usual choice
owners and architects face when considering building materials for their
construction projects.
Precast concrete wall panels, however, make all of these available by offering
design flexibility, time savings and improved profitability.

29
Fig.20 PRECAST WALL
9.6 Concrete precast stair:
Precast stairs are manufactured from bespoke moulds and can be produced as
straight flights with separate or attached landings. Curved, upstands and insert
nosings are also available and stairs can also include provision for progressive
collapse. Stairs are manufactured with the ability to allow for temporary handrails.
With the market continuing to move away from wet trades, precast offers finished
landings and hidden connections with their products subject to design practicability.
Installation of precast staircases is efficient and ready to use with immediate access
improving site safety.

30
Fig.21 Concrete precast stair
9.7 In-fill Terrace Units:
In the case of in-fill terrace units, it is unlikely to be acceptable to provide a new
full wall panel system, since usable area will be sacrificed. In these types of
projects, the wall panel is recommended to be modified as shown in Figure 3.8. For
this type of arrangement, it is likely that design as a plain concrete member will not
be possible and lapping of some vertical bars would be required. A thickness of
180mm is recommended for these panels, to enable consistency and hence economy
of the precast production.

31
Fig.22 In-fill Terrace Units
9.8 PRECAST NON-LOAD BEARING FAÇADE PANELS
Typically, the wall panels for the front and rear elevations are non-load bearing
façade elements. Support of these panels is achieved by any of the following
methods:
 The façade panel is connected to main load bearing walls and is designed to
carry its own weight between support.
 The façade panel is connected to the floor slab or beam, which is then
designed to provide support to the wall.

32
Fig.23 PRECAST NON-LOAD BEARING FAÇADE PANELS

33
CHAPTER 10
STAGES OF PREFABRICATED CONCRETE PRODUCT

35
CHAPTER 11
TYPICAL CONNECTION OF PRECAST CONCRETE
ELEMENTS
Component or end item comprising of a number of parts or subassemblies put
together to perform a specific function, and capable of disassembly without
destruction. What may be an assembly at one point, however, may be a subassembly
at another. In the case of prefabricated RCC structures there are various structural
element such as column, beam, slab etc. are assembled together. There is assemble
of the same elements also like column to column or different elements like beam
and slab. There are three kinds of connections or joints are provided on the
prefabricated structures.
11.8Column to column Connection
Column-column connections may be by threaded rods joined with an appropriate
connector; with concrete subsequently cast round to the dimensions of the cross-
section of the column. Alternatively, bars in grouted sleeves, as described above,
may be used. This results in a thin stitch between columns while the previous
approach requires a deeper stitch. Connections may be located between floors, at a
point of contra-flexure, or at floor level. Columns are provided with necessary
supports for the ends of the precast beams (corbels or cast-in steel sections). There
will also be some form of connection to provide beam-column moment connection
and continuity. For interior columns this may be by holes through which reinforcing
bars pass from one beam to another.
Fig.24 Column to column connections

36
11.2 Beam to column connections
An experimental investigation was conducted to study the behavior of semi rigid
precast beam-column connections subjected to simulated seismic forces. Four full-
scale interior beam-column assemblies representing a portion of a frame subjected
to simulated seismic loading were tested, including one monolithic specimen and
three precast specimens. The behavior differences of these types of connections
with respect to strength, ductility, stiffness, energy dissipation, and deterioration at
the joint core are presented and discussed. Test data showed that properly designed
precast beam-column connections maintained ductility and strength and exhibited
excellent energy-dissipating capacity when subjected to large inelastic
deformations under load reversals.
Fig.25 Beam to column connections
11.3 Beam to slab joint
In the beam to slab joint, the slab is placed with the connection of the beam. It is properly
attached with the beam. It is also known as column-beam-slab connection.
The hollow core slab is used as prefebricated slab because is easily attached to the beam.

37
Fig.26 Beam to slab joint
11.4 Wall to slab connection
Slab to Wall Connections Projections in precast concrete walls to support the inverted-tee
beams or the double-tee floor slabs. Beam to Column Connections Projecting Bracket.

38
Fig.27 Wall to slab connection
11.5 Slab to slab connections
Slab to Slab Connections Grout keys provide structural continuity between floor slab
units. Connections between hollow-core slabs and supporting members are made using
site-cast concrete fill and reinforcing steel. In addition to the concrete fill used for
connections, a site-cast concrete topping is generally used over the slabs. The topping
provides structural integration of slab units and increases the floor’s fire resistance and
sound insulation. It also functions as a leveling bed, particularly with units with uneven
camber.
Fig.27 Slab to slab connections

39
11.6 Panel to panel connections
Panel to Panel Connections Precast panels are connected to each others or to floor and
roof elements by using metal plates and angels, they are fastened by welding or bolting.
Connections may be projected or recessed to provide flush finishing surface. Different
cases of precast panel to panel connections. Column to Column Connections Precast
concrete columns are connected together through bolting, the top of a lower-floor
column contains threaded bolts projecting out, while the bottom of an upper-floor
column has an embedded base plate containing holes to engage the bolts.
Fig.28 Panel to panel connections
11.7 Column to foundation connections
The method of connection to the foundation and to the column above will vary with
manufacturer. Foundation connection may be via a base plate connected to the
column or by reinforcing bars projecting from the end of the column passing into
sleeves that are subsequently filled with grout. Alternatively, a column may be set
into a preformed hole in a foundation block and grouted into position. Column to
base connections may be by threaded rods joined with an appropriate connector;
with concrete subsequently cast round to the dimensions of the cross-section of the
column. Precast Concrete Extra Details Partial precast concrete hollow core slab
over metal hanger to provide an opening. Lifting hooks are very important
component in precast concrete units.

40
Fig.29 Column to foundation connections

41
CHAPTER 12
CONNECTION DETAILS
12.1 Choice of connections
In precast concrete construction the connections between the elements are of utmost
importance. There are two types of connections, one "Wet" connections (with motor
or in-site concrete), second is 'Dry' connections (with welding on bolting). While
choosing a connection, so many factors we have to consider. The connection should
satisfy in technical, economical, and if required - aesthetical respect, the following
considerations shall be taken into account.
12.2 Structural requirements:
The connection must comply with all requirements regarding the transmission of
forces and moments, and permissible deformation or rotation.
12.3 Tolerances:
The measure to which deviations must be taken up in the connection.
12.4 Aesthetical requirements:
The connection remains completely or in part exposed.
12.5 Mode of erection:
With regard to available erection equipment (cranes etc.) fastest possible erection
(short crane times), and avoidance or minimizing of bracing, supporting etc ..
12.6 Necessity of checking and adjusting:
The connection and/or the elements.
12.7 Finishing requirements:
With regard to corrosion protection, fire resistance, appearance and maintenance.
12.8 Manufacture:
Manufacture of the elements and the connecting parts should be technically and
economically justifiable.

42
12.9 Transportation and storage:
The shape of the elements (including the provisions for the connection) as related
to problems during transportation or storage at plant and/or building site.
12.10 Costs:
These are mainly detennined by the structural requirements and the number of
connections. For an economic choice, the costs of the connection proper (inc!. its
finishing) should be weighed against the costs of manufacturing, transportation,
storage and the erection of the elements.
12.11 Designing the connection
While designing the connection following points must be considered. Design of
connection must be based on the relevant standard specifications, codes of practice,
rules or by-laws and any other special requirement or recommendation which might
be relevant
12.12 Loading under working conditions
The entire structure, as well as each unit units own, must be designed to resist all
loads, forces and moments, acting there on when the structure is in use. Eccentric
load on an internal column, torsion of main beam.
12.13 Stability of the structure
The overall stability of the structure must be warranted during each phase of
construction. This might require special provisions.
12. 14 Load conditions during construction
Load conditions during construction may cause higher stresses than those through
normal usage. Temporary eccentric loading of an internal column. temporary
additional loads due to erection materials and temporary supports.
12.15 Effects of shrinkage, creep and temperature
With fixed-end beam connections the stresses and moments due to shrinkage, creep
and temperature drop of the beams must be considered for the connection proper
and for the structure as a whole.

43
CHAPTER 13
LOCATION OF JOINT
The location of joints between external wall panels should be selected based on
careful consideration of the following factors:
Structural Considerations External wall panels may be load bearing (e.g. side walls
of corner terrace, semi-detached or detached) or non-load bearing (e.g. front and
rear façade panels). In selecting panel joint locations, it is important to consider the
panel stability (i.e. ability to resist horizontal loads such as wind pressure or loads
specified in the Building Regulations Fourth Schedule).
1. Aesthetics Whilst in general, panel joints are not highly visible, locations
should be selected which minimize any potential impact on the external
façade aesthetics. In general, vertical joints should align for the full height
of the building and would preferably be located symmetrically with respect
to adjacent features.
2. Panel Weight The weight of panels will dictate the crane capacity required
for installation of the wall panels. Apart from the disadvantage of higher
cost, larger capacity cranes may not be able to access the site. For typical
conditions, a weight limitation of approximately 4 tones is considered likely
to be applicable. In general, the panel size should be maximized, leading to
increased speed of construction and reduced number of panel joints to be
treated.
3. Transport Limitations for transportation purposes, it is necessary to limit one
of the panel dimensions to 3.6m. In general, panel heights will be less than
3.6m and panel length is based on weight or other considerations. When the
required panel height exceeds 3.6m, the length of panel will be reduced to
3.6m or less. Early planning for site access must be undertaken, particularly
when houses are built along Category 5 road.
4. Internal Crack Control To minimize the risk of cracks appearing at the
internal face of wall panel joints, the following considerations are relevant:
If possible, locate panel joints at internal wall intersections, inside service
ducts or wardrobes and at other non-visible locations. - Avoid panel joints

44
towards midspan of floors, where beam or slab deflections could lead to joint
opening.
CHAPTER 14
RECOMMENDATIONS FOR THE ERECTION
14.1 Setting out and marking
Prior to erection, all measurements must be checked and sufficient marks set out to
enable fast and accurate erecting.
14.2 Anchor bolts and dowel bars
In placing groups of bolts or dowel bars, one bolt (dowel bar) in each group should
be getting out to facilitate location of the member, or even better the tops of all bolts
(dowel bars) should be so defined that even the shortest bolt is sufficiently long to
allow minor adjustments.
14.3 Mortar or Cast -in-place Joints
The performance of these joints depends on the strength of the hardened mortar or
in-situ concrete. The mix should be aimed at achieving full compaction with the
available means, and on the other hand at keeping shrinkage to a minimum. This
latter requirement also called for extensive curing. Since hardening of the motor
(concrete) is influenced by the ambient temperature, such measures as the use of
rapid hardening or Ultra rapid hardening cement, heating of the mortar or the.
Concrete and even heating of the adjacent precast concrete might be required during
the cold season.
14.4 Dowel holes
For grouting dowel holes the following possibilities may be considered.
14.5 Upward dowel holes
It can be grouted either by injecting or by pouring a sand-cement grout containing
a cement grout containing a cement not susceptible to bleeding, or by a pure cement
grout with an injection agent.
14.6 Downward dowel holes

45
Which are cast in, can be grouted similarly. If they are drilled, these should be filled
either with a grout to which a synthetic resin dispersion agent is added, or with a
synthetic resin with a quartz filler. In any case these holes must be filled just prior
to placing the dowel bars and must then be clean and air-day.
14.7 Recesses, pockets
Depending on the size, these should be filled with a dry to half plastiC sand-cement
mortar or in-situ concrete to which a synthetic resin dispersion agent might be added
for better bonding.
14.8 Welding of reinforcing bars
Welds between reinforcing bars, pertaining to the same joint, should be as nearly
identical as possible. To attain this each pair of bars to be welded in the same joint
should be so bent, and if necessary cut, that the distance between the welding faces
are equal to that of the other pairs. Furthermore there must be sufficient room
between the concrete faces for laying the welds, and the bars should have sufficient
projection to prevent overheating of the concrete. A minimum distance of five times
the bar diameter between the edge of the weld nearest to the. Concrete and the
concrete face is in this respect considered to sufficient. Moreover, welding
operations should confinn to the relevant standard specifications, codes of practice
etc.
14.9 Stability measures during erection
The overall stability of the structure as well as the stability of each element should
be ensured by temporary supports, struts, braces etc. Until the connections are load
transferring. Erection equipment (cranes etc.) Should there by not be obstructed.
This may influence the order of erection.
14.10 Corrosion protection
Projecting reinforcing bars are for the same reason liable to corrosion at the
interface between the precast element and the in-situ concrete or mortar fill. For this
reason these bars should also be corrosion protected over a short distance from both
sides of the interface with a coating of epoxy, rustproof points. If they are welded
the same applies as set out for steel parts.

46
CHAPTER 15
DESIGN CONSIDERATION
There are various design consideration for the design of prefabricated RCC
structures which is as follows:-
1. final position and loads
2. transportation requirements – self load and position during transportation
3. storing requirements – self load and position during storing – (avoid or store
in the same position as it transported / built in)
4. lifting loads – distribution of lifting points – optimal way of lifting (selection
of lifting and rigging tools.
5. vulnerable points (e.g. edges) – reduction of risk (e.g. rounded edges) 10

47
CHAPTER 15
EQUIPMENT
There are various equipment used in prefabricated RCC structures.
15.1 Cranes:-
A crane is a type of machine, generally equipped with a hoist rope, wire ropes or
chains, and sheaves, that can be used both to lift and lower materials and to move
them horizontally. It is mainly used for lifting heavy things and transporting them
to other places. The device uses one or more simple machines to create mechanical
advantage and thus move loads beyond the normal capability of a human. Cranes
are commonly employed in the transport industry for the loading and unloading of
freight, in the construction industry for the movement of materials, and in the
manufacturing industry for the assembling of heavy equipment. Cranes also have
two types.
1. Mobile cranes
2. Tower cranes (above 3 stories)
Fig.30 Cranes

48
15.2 Lifting tools:-
The erection of precast elements can be a stupendous and absorbing sight; it requires
a very careful choice of the right lifting devices, equipment, personnel, safety
measures and assiduous planning to ensure efficient and quality installation and to
reap the full benefits of Precast Construction. The erection of precast elements at
the right locations, with the correct levels and alignments with necessary grouting /
castings at all the intersection of the precast members plays the key role as the
complete precast structure designed has to fulfill the function of the building desired
by the Architect / Engineer. Therefore a clear process plan, with the exact sequence
of construction, the methodology of integration of elements, supporting systems,
lifting arrangements is all very much essential for a precast building. There are also
two types of lifting tools are used in prefabricated concert.
1. Spreader beams
2. Wire rope slings
Fig.31 Spreader beams

49
Fig.32 Wire rope slings
15.3 Rigging tools:-
A team of riggers design and install the lifting or rolling equipment needed to raise,
roll, slide or lift objects such as with a crane or block and tackle. Rigging comes
from rig, to set up or prepare. Rigging is the equipment such as wire rope,
turnbuckles, clevis, jacks used with cranes and other lifting equipment in material
handling and structure relocation. Rigging systems commonly include shackles,
master links and slings. Also, lifting bags in under water lifting. There are various
type of rigging tools are used in prefabricated structures.
1. Eye bolt
2. Shakles
3. Hooks
Fig.34 Shakles
Fig.33 Eye bolt

50
Fig.35 Hooks
CHAPTER 16
COST- BENEFIT ANALYSIS
16.1 Cost of Construction of Conventional Structures in Railways
The cost of construction of various conventional structures has been collected from
Railways, based on the constructions carried out in recent past. However in order
to keep uniformity with the offers received from prefab structure
manufacturer/supplier, the unit cost of construction per square meter has been
calculated below after excluding the cost of excavation & construction of
foundations, floorings, plumbing and sanitary fitting. The cost of electrical works
has also been excluded. Accordingly the average unit cost of various conventional
structures/buildings in Railways has been worked out as under.

51
16.2. Cost of Construction using Prefab Structures
For estimation of unit cost of various structures using Prefab, various construction
agencies engaged in prefab construction were contacted. M/s Everest Industries
Limited has provided the estimate for staff quarters and workshop building while
M/s Kirby Building Systems India Ltd. has provided the estimate for standard
platform shelter. Besides this, offered rates received from various prefab agencies
for construction of ROH depot shed at Gonda, NER and accepted rates of M/s
Metecno (India) Pvt. Ltd., Chennai, who have completed the construction of
prefabricated housing in the township of Rail Coach Factory at Raibareli have also
been considered.
In the estimate/offer submitted by M/s Everest Industries Limited & M/s Kirby
Building Systems India Ltd., following items/services will be provided by the firm:
1. Design and detailed drawings for steel frame work.

52
2. External and internal wall and roof truss steel structure.
3. Roof sheeting of coated galvalume sheet.
4. Roof and wall insulation including external and internal wall cladding.
5. False ceiling
6. Fabrication, Transportation from shop to site and Erection of the same.
However, the followings works are not included in their offer:
i) Foundations.
ii) Electrical fittings.
iii) Door/Windows.
iv) Plumbing.
v) Internal & external wall finishes including final painting, interiors etc.
A) Unit cost of Staff Quarter using prefab structure provided by M/s Everest
Industries Limited, New Delhi

53
B) Unit cost of Single and Double room Cabins/ Accommodation using Prefab Structure
provided by M/s Metecno (I) Pvt. Ltd. Chennai (Rates are based on their accepted
rates against tender No. IRCON/Civil/1029/RCF-RBL/10/Tender/3/LT-11 for the
Rail Coach Factory/ Raibareli):
S.N. Item Unit Rate
1. Single Room Accommodation (Total 40 units to be provided):
Each unit shall consist of following:
a) One room of size 4.78m x 3.6m and height 3.0m and 2.7m
with verandah 1.2m wide.
b) One no. door of size 2.1m x 0.9m with powder coated G.I.
frame and powder coated G.I. Flush doors, 44 mm thick, with
honey comb construction kraft paper/ mineral wool/PUF infill,
with reinforcements at hinges, door closer and lock case
fitments, in desired color and fittings.
c) Two windows of size 1.2m x 0.9m of powder coated
G.I.frame, fully glazed with two sliding shutters each 25mm
thick in desired colors and fittings.
sqm
Rs. 11305/-
2. Two room accommodation (Total 10 units to be provided)
Each unit shall consist of
a) living room size 3.5m x 4.0m
b) bedroom size 4.35m x 3.6m,
c) Toilet 1.80m x 2.0m,
d) kitchen 2.15m x 2.0m,
e) Verandah 1.2m wide.
f) Doors 3 nos. of size 2.1m x 0.9m and one no. of size 2.1m x
0.75m with powder coated GI frame and powder coated
G.I.flush doors 44 mm thick with honey comb construction ,
Kraft paper/Mineral wool/PUF infill, with reinforcement at
hinges, door closer and lock case fitment infill in desired colors
and fittings
g) Windows 4 nos. of size 1.2m x 0.9m of G.I. powder coated
fully glazed with two sliding shutters each 25mm thick in
desired colors and fittings.
h) Ventilator 1 no. of size 600mm x 600mm with powder coated
G.I. frame
sqm Rs. 17384/-

54
C) Unit cost of PF Shelter using Prefab Structure provided by Kirby Building Systems
India Ltd., New Delhi.
Technical specification for Pre-Engineered Platform Shelter is annexed as
Annexure- B and The rate details submitted by M/s Kirby Building Systems
India Ltd. is annexed as Annexure- B-1.
S.N. Description of Item for Platform shelter Cost per meter sq.
1. Designing, fabrication, supply & erection of pre-
engineered building for Railway’s standard platform
shelter having covered area of 108 sq. with galvalume sheet
roofing and two coats of synthetic enamel paint through
certified builder with separate work order.
Rs. 5555/-

55
D) Unit cost of PF Shelter using Prefab Structure provided by Kirby Building Systems
India Ltd., New Delhi.
Technical specification for Pre-Engineered Platform Shelter is annexed as
Annexure- C and The rate details submitted by M/s Kirby Building Systems
India Ltd. is annexed as Annexure- C-1.
E) Unit cost of Workshop using Prefab Structure received by Dy.CE/Con/Bridge
workshop Gorakhpur, for ROH depot shed at Gonda, NER:
Recently, a tender for ‘Construction of ROH shed at Gonda including Architectural &
steel Design, fabrication, supply and erection of Pre-Engineered Steel Building’ was
floated in NER. The offer details are as under
S.N. Description of Item of Workshop Building
with 10T EOT crane
Cost per
square meter
1. Design, engineering and detailing & erection of
structural steel in columns and rafters, providing
& commissioning of crane brackets, structural
steel in purlins, anchor bolts, nuts, washers and
templates, structural steel in gusset plates,
bracings and sag rods etc., structural steel in
gantry beams, roofing sheets in bare galvalume
0.47m TCT, Wall cladding in colored galvalume
0.50mm TCT, Gutters and downpipes with
accessories, Hardware of all kinds, painting of
enamel paint 2 coats at site.

56
• The size of ROH depot shed is 100 m x 62 m with clear height of 13.70 m. above tender is
under finalization.
• Civil foundation and flooring is not under the scope of work
F) Comparative unit cost of construction - Prefab Structures vis-à-vis Railway’s LARs:

57
CHAPTER 17
ADVANTAGES, DISADVANTAGES & LIMITATION
17.1 Advantages
1) Moving partial assemblies from a factory often costs less than moving
pre-production resources to each site
2) Deploying resources on-site can add costs; prefabricating assemblies
can save costs by reducing on-site work
3) Factory tools - jigs, cranes, conveyors, etc. - can make production faster
and more precise
4) Factory tools - shake tables, hydraulic testers, etc. - can offer added
quality assurance
5) Consistent indoor environments of factories eliminate most impacts of
weather on production
6) Cranes and reusable factory supports can allow shapes and sequences
without expensive on-site false work
7) Higher-precision factory tools can aid more controlled movement of
building heat & air, for lower energy consumption and healthier
buildings
8) Factory production can facilitate more optimal materials usage,
recycling, noise capture, dust capture, etc.
9) Machine-mediated parts movement, and freedom from wind & rain can
improve construction safety
10)Quick erection times
11)Possibility of conversion, disassembling and moving to another site
12)Possibility of erection in areas where a traditional construction practice
is not possible or difficult
13)Low labor intensively
14)Reduce wastage of materials
15)Easier management of construction sites
16)Better overall construction quality
17)Ideal fit for simple and complex structures

58
17.2Disadvantages and Limitations
1) Size of the units.
2) Location of window openings has a limited variety.
3) Joint details are predefined.
4) Site access and storage capacity.
5) Require high quality control.
6) Enable interaction between design phase and production planning.
7) Difficult to handling & transporting.
8) Transportation costs may be higher for voluminous prefabricated
sections than for their constituent materials, which can often be
packed more densely.
9) Large prefabricated sections may require heavy-duty cranes and
precision measurement and handling to place in position

59
CHAPTER 18
CONCLUSION
On the comparison of unit cost of conventional structures collected from zonal
railways on the basis of construction carried out in recent past and the estimates and
LARs obtained from reputed prefab construction agencies, it is observed that in case
of workshop sheds and platform shelters, the construction cost of prefab structure
is almost at par with Railway’s cost. However, for smaller structures like isolated
staff quarters etc., the cost of prefab structure is much higher than the conventional
structures. On interaction with the industry, it was informed that for bigger steel
structures like large maintenance sheds/depots and platform shelters having area
more than 10,000 sq.m., the construction cost using prefab structure is expected to
further reduce by 10-15%. Similarly for row housing projects, the cost of
construction may also get further reduced by 10-20%. For staff quarters, row
housing projects and construction of gate lodge and staff quarters for manning of
level crossings, use of prefab construction should be considered where saving of
time is of prime importance. Use of prefab structure will considerably reduce the
construction time and post construction maintenance requirements. Also many
readymade prefab structures/porta cabins are available in the market, which can be
transported and erected quickly. Portability of the structure is another important
aspect to be considered which is useful in case of construction of site office and
labor hutments etc. For bigger steel structures like workshop sheds and platform
shelters, prefab structure are designed as per site condition and their members are
lighter in comparison to conventionally designed steel structures. From the study it
is observed that the requirement of steel is reduced by 15-25% in case of pre-
engineered structures. Approximately 10% of the cost can also be saved in the
construction of foundations. The post construction maintenance requirement of
prefab structure is lower in comparison to conventional steel structures, which also
reduces the post construction expenses. As discussed with prefab structure
manufacturer, the construction of staff quarter/row housing is suitable only for
single floor. As the pre-engineered building construction is in their initial stage in
India, the in-service performance cannot be assessed.

60
BIBLIOGRAPHY
1. Ashok. K. Jain - "Reinforced concrete" (Limit State Design) New Chand &
Bros., Civil Lines, Roorkee.
2. Beton - Verlag, "Precast concrete connection details
3. "Building Research Note" - Central Building Research Institute, India.
4. IS; 456-1978 "Indian Standard Code of Practice for Plain and reinforced
concrete. Bureau of Indian Standards, New Delhi - 2.
5. IS: 800-1984 "Indian Standard Code of Practice for General Construction in
Steel, Bureau of Indian Standards, New Delhi - 2.
6. IS: 875-1987 (Part I), "Code of Practice for Design Loads in Buildings and
Structures Dead Loads, Bureau of Indian Standards, New Delhi - 2.
7. IS: 875-1987 (Part II), "Code of Practice for Design Loads in Buildings and
Structures Imposed Loads, Bureau of Indian Standards, New Delhi - 2.
8. IS: 2911-1978 (Part III) "Code of Practice for Design of Under reamed piles.
Bureau of Indian Standards, New Delhi - 2.
9. Krishna Raju. N., "Advanced Reinforced Concrete Design", CBS Publishers
& Distributors, Delhi - 32.
10. Wikipedia
11. Google

Reports on Precast System

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à Reports on Precast System

Similaire à Reports on Precast System (20)

Dernier

Dernier (20)

Reports on Precast System