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UNIVERSITI TEKNOLOGI MALAYSIA
BORANG PENGESAHAN STATUS TESIS♦
JUDUL : SIMULATION OF INDUSTRIALISED BUILDING SYSTEMCOMPONENTS PRODUCTION
SESI PENGAJIAN : 2005 / 2006
SayaNG SOON CHING(HURUF BESAR)
mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah)* ini disimpan di PerpustakaanUniversiti Teknologi Malaysia dengan syarat-syarat kegunaan seperti berikut:
1. Tesis adalah hakmilik Universiti Teknologi Malaysia.2. Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan
pengajian sahaja.3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi
pengajian tinggi.4. ** Sila tanda ( √ )
SULIT (Mengandungi maklumat yang berdarjah keselamatan ataukepentingan Malaysia seperti yang termaktud di dalamAKTA RAHSIA RASMI 1972)
√ TERHAD (Mengandungi maklumat yang TERHAD yang telah ditentukan olehorganisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkan oleh
(TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)
Alamat Tetap:PROF. MADYA DR. ABDUL KADIR
1291, JALAN BESAR, MARSONOSUNGAI BAKAP, Nama Penyelia
14200 SUNGAI JAWI.
Tarikh: April 2006 Tarikh: April 2006
CATATAN: * Potong yang tidak berkenaan.** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULITatau TERHAD.
♦ Tesis dimaksudkan sebagai tesis bagi ijazah Doktor Falsafah dan Sarjana secara penyelidikan,atau disertai bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek SarjanaMuda (PSM).
Status Declaration Letter
Date : April, 2006
LibrarianPerpustakaan Sultanah ZanariahUTM, SkudaiJohor
Sir,
CLASSIFICATION OF THESIS AS RESTRICTED
SIMULATION OF INDUSTRIALISED BUILDING SYSTEMCOMPONENTS PRODUCTION
NG SOON CHING
Please be informed that the above mentioned thesis entitled “SIMULATION OFINDUSTRIALISED BUILDING SYSTEM COMPONENTS PRODUCTION” beclassified as RESTRICTED for a period of three (3) years from the date of this letter.The reasons for this classification are
(i) COMMERCIALIZATION OF RESEARCH PRODUCT(ii) NEGOTIATION STAGE WITH UTSB SDN. BHD. AS BUSINESS
CONSULTANT(iii) NICHE IBS PRODUCT COMPONENTS ARE WAITING TO BE
MANUFACTURED
Thank you.
Sincerely yours,
ASSOC. PROF. DR. ABDUL KADIR MARSONOM46-23807-5531606013-7257737
“We hereby declare that I have read this project and in my opinion this project is
sufficient in terms of scope and quality for the award of the degree of Master of Science
(Construction Management) by taught course.”
Signature : ………………………………………
Name of Supervisor I : ASSOC. PROF. DR. ABDUL KADIR
MARSONO
Date : April 2006
Signature : ………………………………………
Name of Supervisor II : DR. MASINE MD TAP
Date : April 2006
Signature : ………………………………………
Name of Supervisor III : ASSOC. PROF. DR. AHMAD MAHIR
MAKHTAR
Date : April 2006
SIMULATION OF INDUSTRIALISED BUILDING SYSTEM
COMPONENTS PRODUCTION
NG SOON CHING
A project report submitted in partial fulfillment of the
requirements for the award of the Degree of
Master of Science (Construction Management)
Faculty of Civil Engineering
Universiti Teknologi Malaysia
APRIL 2006
“I declared that this project report entitled “Simulation of Industrialised Building
System Components Production” is the result of my own research expect as cited in
references. This report has not been accepted for any degree and is not concurrently
submitted in candidature of any degree”.
Signature : ……………………
Name : NG SOON CHING
Date : APRIL 2006
To my beloved family and fiancée
ACKNOWLEDGEMENT
I would like to express my deepest gratitude to my supervisor, Associate
Professor Dr. Abdul Kadir Marsono, for his enthusiastic assistance and guidance
throughout the work. His admirable endeavor on the front line of education and research
work is gratefully appreciated. It is indeed to work with such a dedicated lecturer and
researcher.
Special thanks are due to Dr. Masine Md Tap and Associate Professor Dr.
Ahmad Mahir Makhtar for their ideas and helps. Besides, I would like to acknowledge
the helps of everyone that contributing to the success of this study either directly or
indirectly.
Finally, appreciation is also acknowledged to my family and fiancée for their
moral supports and concerns.
ABSTRACT
The construction of IBS building starts with the production of the IBS
components and the production process is the main activity concern in the IBS
production plant. Having an optimum production line to manufacture the required IBS
elements within targeted time and limited number of reusable steel mould is very
important. In this study, workstation organization method has been adopted in the
production of IBS beam and column. Witness 2001 simulation software has been used
to model and simulate the most optimum production line set up. Basically, two
production lines set up have been proposed to complete the production of IBS beam and
column between two and three months time with limited number of reusable steel mould
to supply for the construction of medium size single storey IBS housing project ranging
from 100 to 300 units. A contingency production line set up which able to complete the
production of required IBS components within a month time with increased number of
reusable steel mould has also been proposed. Number of resources such as workstation,
tool, storage area and labour has been determined from the proposal. The proposed
production line can be applied in the planning and cost estimating of IBS production
plant set up.
ABSTRAK
Pembinaan IBS bermula daripada operasi pembuatan komponen IBS di loji.
Susunatur dan talian pengeluaran yang optima di sesebuah loji adalah penting dalam
menghasilkan komponen IBS dalam masa yang tertentu serta dengan bilangan acuan
yang terhad. Dalam kajian ini, kaedah pembuatan yang diaplikasikan ialah kaedah
pengkhususan dan jumlah bilangan komponen IBS yang perlu dihasilkan adalah
berdasarkan projek sederhana dalam lingkungan 100 hingga 300 rumah satu tingkat
yang menggunakan komponen IBS sepenuhnya dalam pembinaan. Perisian komputer
Witness 2001 telah digunakan untuk kerja memodel dan simulasi untuk menentukan
talian pengeluaran yang optima. Terdapat dua cadangan talian pengeluaran yang
berupaya untuk menghasilkan bilangan komponan rasuk dan tiang IBS dengan bilangan
acuan yang terhad dalam masa dua dan tiga bulan untuk memenuhi keperluan projek
sederhana. Selain itu, talian pengeluaran yang dapat menghasilkan komponen IBS yang
diperlukan dalam masa satu bulan dengan peningkatan bilangan acuan turut dicadangkan.
Bilangan mesin, peralatan, tenaga perkerja dan tempat simpanan sementara turut
ditentukan berdasarkan talian pengeluaran yang dicadangkan. Perancangan dan
penganggaran kos penubuhan loji pembuatan komponen IBS dilakukan berlandaskan
cadangan talian pengeluaran tersebut.
TABLE OF CONTENTS
CHAPTER ITEM PAGE
TITLE i
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xii
LIST OF FIGURES xiv
LIST OF APPENDICES xvi
CHAPTER 1 INTRODUCTION 1
1.1 Introduction 1
1.2 Problem Statement 3
1.3 Aims and Objectives of Study 3
1.4 Scope of Study 4
1.5 Importance of Study 5
CHAPTER 2 LITERATURE REVIEW 6
2.1 Introduction 6
2.2 Precast Building System in Malaysia 7
2.2.1 Barriers to the Adoption of IBS
in Malaysia 8
2.2.2 Government and CIDB Initiative 10
2.3 Types of IBS System 11
2.3.1 Essential Characteristic of IBS 15
2.3.1.1 Closed System 16
2.3.1.2 Open System 17
2.3.1.3 Modular Coordination 17
2.3.1.4 Standardisation and
Tolerances 18
2.3.1.5 Mass Production 19
2.3.1.6 Specialisation 19
2.3.1.7 Good Organisation 19
2.3.1.8 Integration 20
2.3.1.9 Production Facility 20
2.3.1.10 Transportation 20
2.3.1.11 Equipment at Site 21
2.3.2 Benefits of IBS Component 21
2.3.2.1 High Quality and Aesthetical
Value of Products 21
2.3.2.2 Cleaner and Safer
Construction Site 22
2.3.2.3 Faster Construction 22
2.3.2.4 Greater Unobstructed Span 22
2.3.2.5 Lower Total Construction
Cost 23
2.4 Production of IBS Element 23
2.4.1 Principle of IBS Production Planning 24
2.4.2 IBS Components Production Process 25
2.4.2.1 Reinforcement Fabrication 25
2.4.2.2 Mould Assembly 26
2.2.4.3 Placing and Compaction 26
2.2.4.4 Stripping and Demoulding 28
2.2.4.5 In-process Checks 28
2.2.4.6 Lifting and Handling 30
2.4.3 Casting Technique 30
2.4.3.1 Wet Casting 30
2.4.3.2 Flat Casting 31
2.4.3.3 Gang Casting 32
2.4.3.4 Stack Casting 32
2.4.3.5 Battery Casting 33
2.5 Prefabrication Plant 34
2.5.1 Types of Prefabrication Plant 34
2.5.1.1 Permanent Plant 35
2.5.1.2 Field Plant 36
2.5.1.3 Fabrication on Building
Site 37
2.5.2 Design of Plant Facilities 39
2.5.3 Plant Layout Design 40
2.5.4 General Layout Pattern 42
2.6 Work Organisation 44
2.6.1 All-purpose Team Method 44
2.6.2 Workstation Method 45
2.7 Simulation Overview 47
CHAPTER 3 METHODOLOGY 49
3.1 Introduction 49
3.2 Data Collection 50
3.2.1 Production Time 50
3.2.1.1 Preparation Stage 51
3.2.1.2 Casting Stage 52
3.2.1.3 Inventory Stage 52
3.2.2 Number of IBS Components 53
3.2.3 IBS Production Plant 54
3.3 Modeling and Simulation 55
3.4 Data Analysis and Discussion 56
3.5 Research Methodology Flowchart 57
CHAPTER 4 DATA AND RESULTS 58
4.1 Introduction 58
4.2 Precast Plant Layout 59
4.3 Activity Duration and Resources 59
4.3.1 Parts Preparation 60
4.3.2 Fixing of Reinforcement Bars 61
4.3.3 Degreasing 62
4.3.4 Concreting 62
4.3.5 Demoulding and Inspection 63
4.3.6 Cleaning and Reassembling of Mould 63
4.4 IBS Beam and Column Required 63
4.5 Working Time and Constraint 65
4.6 Modeling 66
4.6.1 IBS Production Modeling 72
4.7 Results 74
4.7.1 Two Months Production Time 75
4.7.2 Three Months Production Time 76
4.7.3 Contingency Plan 77
CHAPTER 5 DISCUSSION 78
5.1 Introduction 78
5.2 Discussion 79
5.2.1 Time 79
5.2.2 Resources 81
5.2.3 Inventory Storage Area 87
5.3 Contingency Plan 89
5.3.1 Time 90
5.3.2 Resources 91
5.3.3 Inventory Storage Area 94
CHAPTER 5 CONCLUSION AND RECOMMENDATION 96
6.1 Conclusion 96
6.2 Recommendation 97
REFERENCES 98
Appendix A – C3 100 - 105
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Building system classification according to relative
weight of component 12
4.1 Parts Preparation Time 61
4.2 The Duration of Every Activity 64
4.3 Total Amount of IBS Element 65
4.4 Effective Working Hour 65
4.5 Number of Steel Mould Available 66
4.6 Part Detail 69
4.7 Buffer Detail 70
4.8 Conveyor Detail 71
4.9 Machine / Workstation Detail 72
4.10 Two Months Production Resources and Time 75
4.11 Three Months Production Resources and Time 76
4.12 Contingency Plan Resources and Time 77
5.1 Two Months Targeted Production Time 80
5.2 Three Months Targeted Production Time 81
5.3 Two Months Beam Production Line Resources 82
5.4 Two Months Column Production Line Resources 83
5.5 Three Months Beam Production Line Resources 83
5.6 Three Two Months Column Production Line Resources 84
5.7 Two Months Production Line Overall Resources 85
5.8 Three Months Production Line Overall Resources 86
5.9 Storage Area Required for Two Months Production Line 88
5.10 Storage Area Required for Three Months Production Line 88
5.11 One Month Targeted Production Time 90
5.12 One Month Beam Production Line Resources 91
5.13 One Month Column Production Line Resources 92
5.14 One Month Production Line Overall Resources 93
5.15 Storage Area Required for One Month Production Line 94
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Industrial Hall 13
2.2 Panel system solutions applied to a typical 14
residential building
(a) room-size slabs on cross walls
(b) modular slabs on cross walls
(c) modular slabs on exterior walls
(d) slabs on beams and columns
2.3 Arrangement of box units into position onsite 15
2.4 Main stages of concrete flow through a prefabrication 40
plant
2.5 (a) Concrete centre, production area and storage area 43
in direct continuation
(b) Common concrete centre curing chamber and storage
area for two departments
2.6 Production with all-purpose team method (two teams) 45
2.7 Production with workstation method (three shifts) 46
3.1 Production Stage 51
3.2 Single Storey 100% IBS House Drawing 53
3.3 Witness 2001 Software Start Up Window 56
3.4 Research Flowchart 57
4.1 IBS Precast Plant Layout 59
4.2 (a) Part Element 67
(b) Buffers Element
(c) Integer
(d) Conveyor Element
(e) Machine Element
4.3 Part Detail Dialog Box 68
4.4 Buffer Detail Dialog Box 69
4.5 Conveyor Detail Dialog Box 70
4.6 Machine / Workstation Detail Dialog Box 71
4.7 Dialog Box of Integer 72
LIST OF APPENDICES
APPENDIX TITLE PAGE
A Production Line Modeling 101
B Production Line Modeling (Run) 102
C1 One Month Production Line Set Up 103
C2 Two Months Production Line Set Up 104
C3 Three Months Production Line Set Up 105
CHAPTER 1
INTRODUCTION
1.1 Introduction
Housing is a major concern for all people in every corner of the world as the well
being of a country is reflected in its people enjoying a certain standard of living. With
the increasing number of population in Malaysia, the government housing policy is
geared toward meeting the objective of ensuring access to adequate and decent shelter to
all citizens, particularly the low-income groups. In implementing this policy, the
quantitative and qualitative aspects of housing development are taken into account.
Therefore, Industrialised Building System (IBS) is the best method and solution
to fulfill the government policy. IBS which enables off-site prefabricated or precast
building components manufactured at factories will enable cost saving and quality
improvement through construction standardisation and reduction of labour intensity. On
top of that, minimal wastage, less site material, a cleaner and neater environment as well
as superior quality controlled will lead to lower total construction costs. Mass production
and shorter construction time are the additional points in helping the government to
achieve its housing policy. There are numerous of advantages of using IBS method in
construction to the contractor as well as the end user if it is proper planned and effective
management in its implementation.
IBS is not new in the Malaysian construction industry, particularly the usage of
steel structures and precast concrete for the construction of bridges, drains and other
infrastructure projects. The success of precast, steel and hybrid construction contributed
to the rapid creation of numerous beautiful and quality structures particularly during
the1995-1998 period. These include the construction of the Bukit Jalil Sports Complex
and Games Village, the Petronas Twin Towers and the LRT lines and tunnels.
Nevertheless, the usage of IBS in housing project is still very low if compared to the
conventional method.
The heart of IBS construction starts with the production of the components by
the precaster. In fact, it is a high risk investment for the precaster to venture in producing
IBS components due to large capital IBS precast plant set up cost and the instability of
construction demand. Hence, it is very challenging as the precasters compete among
themselves for business opportunities, technology and quality in production and market
reputation. They have to maintain a good reputation in the market by fulfilling the
requirements and specifications set by the client in terms of cost, quality, time and
consultation. Therefore, a highly structured planning and operation system is required to
manage the production of IBS components in order to optimize the profit and
productivity as well as to survive in the global market.
1.2 Problem Statement
IBS components such as beam and column are produced in the precast plant with
superior quality control and supervision. There are a few important aspects that the
precaster needs to consider before venturing into this business. The precaster needs to
properly plan the layout of the precast plant, equipments and machineries needed, hiring
of skilled labours as well as general workers, having enough capital to run the operation
and so on. A good planning on resources will enable the precaster to meet the supply of
IBS elements to their client in time.
Basically, there are two alternatives of work organization available for the
production of IBS component which are all-purpose team method and workstation
method. The precaster has to carefully consider on which work organization method to
be applied in the production of IBS component as each of these work organizations has
their own advantages and disadvantages. However, the appropriateness and efficiency of
these two work organization methods is highly depends on the volume of production,
number of workers engaged, facilities used and time.
1.3 Aim and Objectives of Study
The aim of this study is to propose the set up of IBS production line and the
number of resources required in the production line set up. This study concentrates on
the management of IBS components production in the precast plant by adopting
workstation organizations method.
There are three specific objectives of this master project:
(i) To propose the optimum production line set up to manufacture the
amount of IBS beam and column required for the construction of a
medium size single storey IBS housing project within two months and
three months time and with limited number of reusable steel mould.
(ii) To propose a contingency production line set up to produce the amount of
IBS beam and column required for the construction of a medium size of
single storey IBS housing project in one month time with increased
number of reusable steel mould.
(iii) To determine the number of resources such as labour, machinery, tool
and storage area required in the proposed production line set up.
1.4 Scope of Study
The scope of work is mainly limited to the production of IBS components
namely beams and columns required for the construction of single storey IBS housing
project ranging from 100 to 300 units. The production process that highlighted in this
study begins from the preparation of parts until the curing process. Limited number of
reusable steel mould available during the production plant is the only constraint in the
production plant. The number of mould used for the production is 125 units for beam
and 75 units for column while the number of reusable steel mould increase to 300 units
for beam and 100 units for column for contingency plan.
The number of workers involved and the time used to produce the IBS
components were observed at the pilot plant and the time required was clocked using
stopwatch. The total amount of IBS components needed for this medium size single
storey IBS housing project was extracted from a 100% IBS house. There are some
assumptions made in this study such as the production will not be interrupted due to
machine breakdown, lack of labours and insufficient supply of raw materials or parts.
The effective working hour for the production plant is six hours per shift and the
production plant is operated in a minimum of one shift and maximum of three shifts per
day.
1.5 Importance of Study
The proposed production line suggested from this study can be applied in the
planning of IBS pilot plant set up. The cost of the production line can be calculated from
the proposal which includes the number of workstations or machineries as well as
labours required. This study also testifies that Witness 2001 simulation software can be
used in to model and simulate an optimum production line set up for IBS production.
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Industrialised Building System (IBS) may be defined as building systems in
which structural components are manufactured in a factory, on or off site, transported
and assembled into a structure with minimal additional site works (Shaari, 2003).
Another definition by Lew et al (2003), IBS is a system in which concrete components,
prefabricated at site or in factory are assembled to form the structure with minimum in-
situ construction. Industrialised System means to build on-site with elements or
components produced by series in plant (Yousre et al, 2002). There is another definition
of IBS suggested by Trikha (1999), IBS may be defined in which all building
components such as wall, floor slab, beam, column and staircase are mass produced
either in factory or at site under strict quality control and minimal site activities. All the
definitions of IBS mentioned about the prefabrication, off-site production and mass
production of building components. According to Richard (2005), industrialisation has
demonstrated a high capacity to reduce the costs, improve the quality and get complex
products available to the vast majority of people.
2.2 Precast Building System in Malaysia
Malaysia first experimented with the idea of precast was in early 1960’s.
Government officers and subsequently the then Minister of Housing and Local
Government visited several European countries to study and evaluate their precast
construction. All of them were impressed by the potential benefits of precast concrete
such as time and eventually cost saving, good quality control and potential transfer of
management as well as technical skills.
In 1964, the government has identified two pilot projects to try out the precast
construction. The first project was in Kuala Lumpur to construct a 7 blocks of 17 storey
flats and 4 blocks of 4 storey shop lots. The second pilot project was located in Penang
with the construction of 6 blocks of 17 storey flats and 3 blocks of 18 storey flats.
After the completion of these two pilot projects, an evaluation was done to
compare the advantages and disadvantages between the IBS with the conventional
systems. The comparisons were focused in terms of cost, speed of construction, labour
requirement and quality control.
According to Harun (1984), the first pilot project which located in Kuala Lumpur
was more expensive than the conventional system for about 8.1%. However, the other
pilot project that located in Penang was cheaper for approximately 2.6% compared to the
conventional system housing project completed around that time. In term of speed, both
pilot projects took 27 months to complete inclusive of the time taken in setting up of the
precast factories. The construction period was comparable to the fastest conventional
construction. From the evaluation of implementing IBS in these two pilot projects, it has
advantages in saving of time and materials involved in the erection of scaffoldings,
shorter construction time and the construction process was not affected by weather
condition as the is no on-site concreting.
Precast construction enabled the saving 30% to 40% of labour requirement to
execute these two pilot projects compared to conventional practice. It has a great saving
of labour especially in the field of brick layers, plasterers and carpenters. In terms of
quality, the finished appearance of the buildings was of a much higher quality than that
achieved in comparable conventionally built low cost housing units. In particular, the
finish of interior walls was much superior to the finish achieved using cement-sand
hollow blocks.
2.2.1 Barriers to the Adoption of IBS in Malaysia
IBS is not new in the Malaysian construction industry, particularly the usage of
steel structures and precast concrete for the construction of bridges, drains and other
infrastructure projects. Nevertheless, the usage of IBS in the Malaysian building industry
is still very low if compared to the conventional methods. The construction industry has
been slow in adoption of IBS due to several reasons:
Wide swings in houses demand, high interest rate and cheap labour cost,
make it difficult to justify large capital investment. Contractors prefer to use
labour intensive conventional building system because it is far easier to lay
off workers during slack period.
Fully prefabricated construction system requires high construction precision.
Malaysian labour forces still lack of skilled workers. Many of foreign skilled
workers had left the country after the widespread crackdown on illegal
foreign workers in recent years. The new batches of foreign workers do not
possess the required skill and have to be retrained.
The construction industry is so fragmented, diverse and involves many
parties. Consensus is required in the use of IBS during planning stage.
However, the owners, contractors and engineers still lack of scientific
information about the economic benefits of IBS.
Lack of research and development in the area of novel building system that
uses local materials. Majorities of IBS in Malaysia are imported from
developed countries, thus driving up the construction cost. Engineering
degrees in local universities seldom teach about the design and construction
of IBS.
The economic benefits of IBS are not well documented in Malaysia. Past
experiences indicated IBS is more expensive due to fierce competition from
conventional building system. Furthermore, there is an abundance of cheap
foreign workers in Malaysia.
The use of IBS in Japan and Sweden are so successful due to high quality and
high productivity. But, in Malaysia, the scenario different, most projects
constructed with IBS were low quality and high construction cost.
Lack of incentive and promotion from government in the use of IBS. Many
architects and engineers still unaware of the basic element of IBS such as
modular coordination (MC).
2.2.2 Government and CIDB Initiative
The usage of IBS in building is still low in our country. From a survey conducted
by Construction Industry Development Board (CIDB) Malaysia, the usage level of IBS
in the local construction industry stands at only 15% (IBS Survey, 2003). The early
efforts of the Government to encourage the use of IBS in the construction sector has yet
to garner a good response and this sector is still practicing conventional construction
methods that have proven time and again to be wasteful, dangerous and messy.
The industry needs one fundamental plan that involves all the important aspects
in this evolution process. In this respect, the IBS Roadmap 2003-2010 is formulated as a
reference for all parties in implementing all programs towards the modernization of the
Malaysian construction sector. IBS Roadmap 2003-2010 is to ensure that its programs
are implemented to meet the total industrialisation of Malaysia’s construction industry
by the year 2010.
The Malaysian Government is also currently very active in promoting the usage
of prefabricated materials, particularly IBS components. The Public Works Department
(JKR), CIDB as well as the Ministry of Housing and Local Government are among the
leaders in championing its usage in the construction industry. JKR has also produced a
new set of drawings utilizing IBS components for its standard quarters. More hostels,
schools, colleges and low cost houses are also now being designed and constructed using
IBS elements. It is hoped that more clients, designers and contractors in the local
construction industry heed to government’s call for the industrialisation of the
construction sector and opt for precast or IBS construction as an alternative to the in-situ
method. The commitment and cooperation between the government and private sector
are crucial in ensuring the success of the program. In order to survive in the era of
globalization, it is important for local players in construction industry change their
perception and begin to use new techniques to produce better quality, productivity and
safety in construction.
The Government is determined to ensure that every Malaysian will have access
to affordable homes. During the period 1971-2003, the Government constructed 490,000
units of low-cost houses while the private sector constructed 509,000 units for low-
income families. The Government intends to provide an additional 100,000 units of
affordable homes to be implemented through the industrialized building system. The
usage of IBS components in Government building projects will be increased from 30
percent currently to 50 percent commencing from year 2005. According to the Prime
Minister, housing developers who utilize IBS components exceeding 50 percent will be
given full exemption on levy imposed by CIDB (IBS Digest, 2005).
2.3 Types of IBS System
From the structural classification, there are three IBS main groups identified as
being used in this country. There are frame system, box system and panel system. Table
2.1 shows building system classification according to relative weight of component.
Table 2.1: Building system classification according to relative weight of component
(Majzub, 1977)
Frame system may be defined as those structures that carry the loads through
their beams and girders to column and finally to the footing or pilecap. Junid (1986) also
stated that, in such a system, the skeletal structures will help to reduce the number and
sizes of load carrying members. Their important feature is the capacity to transfer heavy
loads over large spans. Therefore, it is used in the construction of bridges, parking lots,
warehouses, industrial buildings and sport facilities.
No General System System Production Material
1 Frame system Light weight frame Wood, light gage metals
Medium light weight frame Metal, reinforced plastics,
laminated wood
Heavy weight frame Heavy steel, concrete
2 Panel system Light and medium weight
panel
Wood frame, metal frame
and composite materials
Heavy weight panel (factory
produced)
Concrete
Heavy weight panel (tilt up-
produced on site)
Concrete
3 Box system
(modules)
Medium weight box (mobile) Wood frame, light gage
metal, composite
Medium weight box (sectional) Wood frame, light gage
metal, composite
Heavy weight box (factory
produced)
Concrete
Heavy box (tunnel produced
on site)
Concrete
Typical systems of linear components for industrial buildings are composed of
structural frames, spaced at equal distances whereby it creates modular linear frame that
can be repeated at a desired number of times. Figure 2.1 shows the example of industrial
hall using frame system.
Figure 2.1: Industrial Hall
The second system is panel system which also known as planar system. Panel
system may be defined as those structures that carry the load through large floor and
wall panels (Junid, 1986). This system probably would be the most widely used
prefabricated system which employed planar or panel-shaped elements for floor slabs,
vertical supports, partitions and exterior wall. Concrete panel systems are extensively
used in Europe for high rise building for ease of construction purpose. In Malaysia, this
system is popularly used in high rise flats and low rise buildings.
Unlike frame system that mainly employed as structural framing, panel systems
also fulfil interior and exterior space enclosure functions. They may be prefabricated
with a considerable amount of finish with a considerable amount of finishing work such
as exterior finish, thermal insulation, electrical conduits and fixtures, plumbing and
window frames. Therefore, panel system will significantly reduce the content and
amount of skilled workers onsite. Hence, this system is widely used in residential
buildings, offices, schools, hotels and similar buildings with moderate loads and large
amount of finish works. Figure 2.2 shows the application of panel system in residential
housing.
(a) (b)
(c) (d)
Figure 2.2: Panel system solutions applied to a typical residential building: (a)
room-size slabs on cross walls; (b) modular slabs on cross walls; (c) modular
slabs on exterior walls; (d) slabs on beams and columns
According to Junid (1986), box system may be defined as those systems that use
three-dimensional modules (or boxes) for fabrication of habitat units. Box system is
useful and preferable because of its compatibility with a high degree of finish in the
factory and its lateral resistance (Bruggeling and Huyghe, 1991). The main features of
this system are in the internal stability as it can withstand load from various directions.
The box system components can be either cast in box-like moulds or assembled
it in the plant from panel form elements. The components may contain a large amount of
finishing works such as wall and floor finishing, electrical wiring and fixtures, kitchen
cupboard, plumbing pipes and windows. This will definitely speed up the construction
time at site. In the case of high rise construction, the degree of factory prefabrication is
reduced for economic reasons of avoiding doubling of wall, ceilings and floors.
Depending on how it is used, the boxes can be made to be load bearing or only support
its own weight. The boxes can be produced in monolithic form such as concrete boxes or
be made in various sections joined together in the factory. Figure 2.3 show the
assembling of box units into position onsite.
Figure 2.3: Arrangement of box units into position onsite
2.3.1 Essential Characteristic of IBS
It is plausible to review the prerequisite characteristics underlining the successful
implementation of industrialized building system (Thanoon, 2003). Each of the
characteristics of IBS is briefly discussed at the following section.
2.3.1.1 Closed System
A close system can be classified into two categories, namely production based in
client’s design and production based on precaster’s design. The first category is designed
to meet a spatial requirement of the client where the spaces required for various
functions in the building as well as the specific architectural design. In this instance, the
client’s needs are paramount and the precaster is always forced to produce a specific
component for a building. On the other hand, the production based on precaster’s design
includes designing and producing a uniform type of building or a group of building
variants, which can be produced with a common assortments of component. Such
building includes school, parking garage, gas station and low cost housing. Nevertheless
these types of building arrangement can be justified economically only when the
following circumstances are observed.
The size of project is large enough to allow for distribution of design and
production costs over the extra cost per component incur due to the specific
design.
The architectural design observes large repetitive element standardization. In
respect to this, a novel prefabrication system can overcome the requirement
of many standardised elements by automating the design and production
process.
There is a sufficient demand for a typical type of building such as school so
that a mass production can be obtained.
There is an intensive marketing strategy by precaster to enlighten the clients
and designer about the potential benefit of the system in term of economics
and noneconomic aspects.
2.3.1.2 Open System
In view of the limitations inherent in the closed system, an open system which
allows greater flexibility of design and maximum coordination between the designer and
precaster has been proposed. This system is plausible because it allows the precaster to
produce a limited number if elements with a predetermined range of product and at the
same time maintaining architectural aesthetic value.
In spite of many advantages in an open system, its adoption experiences one
major setback. For instance, joint and connection problem occur when two elements
from different system are fixed together. This is because similar connection technology
must be observed in order to achieve greater structural performance.
2.3.1.3 Modular Coordination
Modular coordination is a coordinated unified system for dimensioning spaces,
components, fittings etc, so that all elements fit together without cutting or extending
even when the components and fittings are manufactured by different suppliers.
The objectives of modular coordination are:
to create a basis upon which the variety of types and sizes of building
components can be minimized. Through a rationalized method of
construction, each component is designed to be interchangeable with other
similar ones and hence, provide a maximum degree of freedom and choice
offered to the designer. This can also be accomplished by adopting a
relatively large basic measurement unit (basic module) and by limiting the
dimensions of building components to a recommended preferred size.
To allow for easy adoption of prefabricated components to any layout and for
their interchangeability within the building. This is achieved by defining the
location of each component in the building with reference to a common
modular grid rather than with a reference to other components.
The modular coordination for building component apply the basic length unit or
module of M=100cm. This allows the designer to apply this size or its multiple in the
production of building components. Although this concept seems to be easy for adoption,
its application involves a great degree of coordination and adjustment in the
manufacturing process and the interfacing aspects of components.
2.3.1.4 Standardisation and Tolerances
For accomplishing the requirement of modular coordination, all components
need to be standardised for production. Such standardisation of space and elements need
prescribing tolerances at different construction stages such as manufactured tolerances,
setting out tolerances and erection tolerances. So that the combined tolerance obtained
on statistical considerations is within the permitted limits.
Production resources can be used in the most efficient manner if the output is
standardized. Then the production process, machinery and worker’s training can be best
absorbed to the particular characteristics of the product.
2.3.1.5 Mass Production
The investment in equipment, human resources and facilities associated with an
industrialized can be justified economically only when large production volume is
observed. Such volume provides a distribution of the fixed investment charge over a
large number of product units without unduly inflating their ultimate cost.
2.3.1.6 Specialisation
Large production output and standardisation of IBS elements allow a high degree
of labour specialisation with the production process. The process can be subdivided into
a large number of small homogeneous tasks. In such working condition, workers are
exposed to their work repetitiously with higher productivity level.
2.3.1.7 Good Organisation
High production volume, specialisation of work and centralization of production
requires an efficient and experienced organization in the capability of high level of
planning, organizing, coordination and control function with respect to production and
distribution of the products.
2.3.1.8 Integration
In order to obtain an optimal result, a high degree of coordination must exist
between various relevant parties such as designer, manufacturer, owner and contractor.
This is achieved through an integrated system in which all these functions are performed
under a unified authority.
2.3.1.9 Production Facility
The initial capital investment for setting up a permanent factor is relatively
expensive. Plant, equipment, skilled worker, management resources need to be acquired
before production can be commenced. Such huge investment can only be breakeven if
there is sufficiently high demand for the products. On the other hand, a temporary
casting yard or factory can be established at the project site in order to minimize the
transportation costs.
2.3.1.10 Transportation
It is found that casting large-panel system can reduce labour cost up to 30
percent. However, these cost savings are partially offset by the transportation costs. The
transportation of large panels is also subject to the road department requirement. These
limitations must be taken into consideration when adopting a prefabrication system.
2.3.1.11 Equipment at Site
For the purpose of erecting and assembling IBS panels into their position, heavy
crane is required especially for multi-storey building. It is therefore important to
incorporate this additional cost when adopting a prefabrication system.
2.3.2 Benefits of IBS Component
Most of the industry players fail to realize that IBS offers better alternative to the
traditional and labour intensive in-situ construction. The main benefits offered by the
usage of IBS elements are:
2.3.2.1 High Quality and Aesthetical Value of Products
IBS products are manufactured in a casting area where critical factors including
temperature, mix design and stripping time can be closely checked and controlled; and
this will ensure that the quality of IBS products are better than cast-in-situ concrete. A
huge sum of money will be saved by not having to do rectification works. Also due to
factory-controlled prefabrication environment, many combinations of colours and
textures can be applied easily to the architectural or structural pieces. A vast range of
sizes and shapes of IBS components can be produced, providing a great deal of
flexibility and offer fresher looks to the structures.
2.3.2.2 Cleaner and Safer Construction Site
Usage of IBS elements eliminates or greatly reduces conventional formworks
and props. IBS construction also lessens the problem of site wastages and the related
environmental problems. The prefabricated products also provide a safe working
platform for workers to work on. Workers and materials are also greatly reduced at the
construction sites. Also, as elements are produced in the plant and mostly designed to be
repetitive, minimal wastage will be experienced at both factory and construction sites.
2.3.2.3 Faster Construction
IBS construction will save valuable time and helps to reduce the risk of project
delay and possible monetary losses. IBS design and production of elements can be
started while the construction site is under survey or earthworks. Production are also
unaffected by weather conditions due to the controlled environment of the casting area.
Also, the usage of large IBS panels will reduce the time taken to complete the structural
works. Therefore, other trades such as painting and electrical wiring can begin work
sooner.
2.3.2.4 Greater Unobstructed Span
The usage of prestressed precast solutions such as the Hollow Core slabs and
Double-T beams offer greater unobstructed span than the conventional reinforced
concrete elements. With having the lesser beams and columns in any structure, it will
provide larger open space. It is very ideal for the construction of places of worship,
warehouses, halls, car parks, shops and offices.
2.3.2.5 Lower Total Construction Costs
All of the above simplify the construction processes and increase productivity,
quality and safety. As a result, the total costs of construction are reduced.
2.4 Production of IBS Element
According to Chan and Hu (2002), it is necessary to look into material selection,
element design, transportation, and site assembly methods as well as pay close attention
to factory layout, inventory control and production scheduling when IBS is applied in
construction industry. The production scheduling and planning have a great impact on
both site construction and plant operations.
IBS building construction starts with the production of IBS elements either in the
precast plant located a distance away or in the construction. The production technology
can be characterized into the materials used for prefabrication, the sequence of
operations that compose the production process and the equipment used for the
production purpose. Main materials used in production are cement, aggregates,
admixtures and reinforcement steel. During the casting process, fixtures such as
electrical conduits, plumbing, window and door frames, bolts and hangers are embedded
in the concrete or attached to it.
2.4.1 Principles of IBS Production Planning
Production in precasting plant involves varies kind of activity and process.
Usually the planning focuses on casting of elements which is the most critical part of the
production. The following principles applied in the production of planning in precasting
plant:
Elements or components must be delivered to the construction site as required
by the erection schedules. This requirement usually overrides all other
considerations, although in some cases construction schedule on site may be
modified due to special workload constraints in plant. In order to be delivered
on a required date, the elements must be cast an ample time before. This time
include their actual production process, finishing operations, necessary curing
or hardening in stock yard, transportation to jobsite and a reserve for possible
delays.
Elements should be produced whenever possible with available resources in the
precasting plant. Investment in new moulds, production lines and handling
equipment is justified only existing resources cannot physically or
economically be adapted to a special requirement or if there is insufficient
resources to produce desired output.
The expense of moulds adaptation should be minimized. Elements should
therefore be assigned to moulds that are appropriate for their size and
production method. The major source of adaptation cost is the work, materials
and time expanded in adjustment of mould frames to the size and shape of new
elements.
Storage cost associated with production should be minimized. In a given
stockyard, the planning dependent storage cost includes the interest on capital
invested in the inventory, handling of the inventory and maintenance expenses.
These costs are directly related to the quantity of inventory.
Fluctuations in the employment of plant workers should be kept to a minimum
number. Such fluctuations may be caused by irregularity of demand and result
in additional overtime, downtime, hiring and layoff expenses. Effects of
temporary slack in demand on employment can be solved by early production
of elements for future use.
2.4.2 IBS Component Production Process
Basically there are five processes involved in IBS production. The process
involves in IBS production includes reinforcement fabrication, mould assembly, placing
and compaction, stripping and demoulding, in-process check and finally lifting and
handling (Richardson, 1991).
2.4.2.1 Reinforcement Fabrication
Reinforcement cages are in most instances fabricated in the controlled conditions
of the steel shop. Steel supervisors play an important role whereby they have to visualize
the reinforcement in three-dimensional form and be able to translate lines and
dimensions into a sensible cage or series of subassemblies capable of being handled into
the mould. Cages must be suitable tied or welded such that they are not displaced or
distorted by handling and casting operations. Other detail to be carefully considered at
this point is the practical aspect as whether it is possible to place and compact concrete
within the mould.
2.4.2.2 Mould Assembly
The IBS component production process commences with the installation of
moulds in the casting shed or on the casting deck. The base of moulds needs to be set
plane and level and it will check regularly as part of the quality control. In some
instances, flexible bushes are inserted between the base and the casting bed to allow the
mould to vibrate freely under the influence of internal and external vibrators. Side
members of the mould are restrained by from climbing off the base while tie rods are
used to retain side members and contain concrete pressure.
Moulds will be treated with mould oil or chemical parting agent prior to insertion
of cast-in fittings, inserts and inclusions. Mould treatments must be compatible with
mould materials and applied carefully according to the maker’s instruction. It is just a
mist of mould treatment needed which leaves the mould face just ‘greasy’ to touch
condition. Excessive application is generally more damaging to the concrete element
than the use of too little oil or release agent.
2.4.2.3 Placing and Compaction
Placing the concrete into the mould would be considered as a major process in
IBS component production. A few manufacturers still manually shovel the concrete to
ensure even distribution within the mould. However, the concrete placing work in large
IBS component manufacturing plant normally assisted by mechanical means such as
conveyors, placers and pumps. Pumping introduces disciplines on the concrete mix
design which are beneficial to the product. Pumps are sensitive to workability and
cohesiveness. Pumpable concrete can generally be easily compacted when place into the
mould through the top opening. Pneumatic placers place the concrete through a
connection at the bottom of the mould to avoid entrapping air. While conveyors provide
an economic means of handling concrete although precautions mist be taken to avoid
separation and the loss of moisture from the mix.
Durability of concrete is dependent to a large extent upon the degree of
compaction achieved during the production process. Achievement of good compaction
must be high on the list of priorities for attention in the production planning. The
consistence and workability of the concrete must be adjusted to suit the method of
compaction employed. IBS component is compacted using methods which include:
Tamping, effort being applied manually or by mechanical means.
Internal vibration using immersion or poker-type vibrator.
External vibrator using motors driving eccentrically mounted weights.
Screeding with manual and vibrator-powered screeds and conforming plates.
Extrusion from static or mobile machines
The use of admixture which produces flowing concrete.
The combinations of these methods may be used according to the specific
production requirements. The used of internal and external vibrators as well as the
extrusion process are the main methods employed in the production of structural
concrete.
2.4.2.4 Stripping and Demoulding
Moulds must be stripped without damage to the concrete element or the mould.
Stripping is always carried out while the concrete is in a relatively green state. Care is
required to ensure that accidental impact does not cause damage and importantly that
elements are properly supported during early lifting and stacking in this green state. In
order to achieve the planned number of reuses while maintaining the specified quality of
product, absolute care is required in removal of elements from moulds or stripping of
moulds from elements.
When the element is stripped, cleared of hole formers and early finishing such as
brushing of retarded surface completed, all duly checked or inspected elements must be
properly cured initially in the casting shed and latterly in the stack yard. Moulds will be
cleaned and prepared for reassembly. Moulds may be moved to service shed if there is
any alteration on it.
2.4.2.5 In-process Checks
In-process checks must be made at all stages. The precaster should be able to
provide records of these checks and actions take where problems were identified.
Checks should be made on at least a sampling basis although in the majority of works,
in-process checks are made on every element prior to concrete placement. The following
details are essential:
Moulds
Cleanliness of casting deck and stillages on which the mould stands. Surface
quality of the mould, cleanliness, application of mould oils and release agents.
Accuracy, general and critical dimensions such as line, level, squareness of section,
location of stopends, location and condition of grout seals.
Reinforcement
Correct type of cage is properly located in the mould. Spacers inserted,
projecting bars properly fixed and jigged.
Cast-in connections and fittings
Correct type of fittings are used and properly jigged into position accordingly.
Connections and attachments are properly located and secondary reinforcement
installed as detailed.
Concrete supply
Concrete grade, workability, timing of concreting operation and placing
sequence are observed. Correct location of compaction equipment and duration of
application are checked.
Finishing and Curing
Screeding, trowelling, washing, brushing and the quality of the basic element are
checked. Primary curing and covering down the product as well as the surrounding
temperature is controlled.
2.4.2.6 Lifting and Handling
Precasting is a mechanical handling intensive process. Organization of speedy,
safe and efficient in handling operations is a key factor in the achievement of economic
precast operations. Profitability of all stages of production begin from the receive of raw
materials to the final installation and erection work at the construction site, is determined
to a large extent by the mechanical handling equipment, skills and methods employed.
2.4.3 Casting Technique
Casting is considered as the main activity in the production of IBS components.
The techniques of production vary from the simple ‘wet cast’ arrangement used for
many years to the highly mechanized techniques. Naturally there has been an overspill
of technology and methods from one section to another. Production methods have also
been modified to incorporate mechanization, if not the complete process, at least of part
of the manufacturing sequence (Richardson 1973).
2.4.3.1 Wet Casting
Wet casting technique is suitable for small numbers of units having a simple
profile. It is sufficient to provide individual moulds of an appropriate quality. The
moulds are set up within a working centre which is preferably covered and enclosed.
The moulds are designed to allow assembly by simple-skilled personnel under the
guidance and instruction of trained supervision.
The flow of materials into the working centre such as steel reinforcement, cast-in
fittings and concrete has to be arranged together with a provision for suitably trained
personnel to maintain services both in the manufacture of sub-assemblies and cut
materials. The working centre must offer facilities for man movement, handling of sub-
assemblies, placement of concrete and removal of the completed work and the mass of
individual components produced. Arrangements must be made for the constant clearing
of work produced during the appropriate cycle and there must be a well defined ‘clear
centre principle’ for this output to be maintained. Wet cast techniques employ structural
concrete with work cube strength in the range of 21 to 50 N/mm2 and slump varying
from 0 to 175 mm with a compacting factor of 0.8 to 0.97.
2.4.3.2 Flat Casting
Flat casting of components offers the opportunity of using a variety of methods
to achieve surface finished on cladding panels. The precaster has a choice in the aspects
of casting ‘face up or face down’ which is invaluable when manufacturing units with
special faces, exposed aggregates, tiles, mosaics and brick slip. By the adoption of flat
casting techniques, thin skin and sandwich production can be used to achieve economy
in materials and the methods of introducing insulants are simplified. Good concrete
placement and compaction can be achieved due to the opportunity for spreading the
concrete mix uniformly throughout the mould and due to ease of applying vibratory
effort.
It must be emphasized that during the process of flat casting, very careful
attention must be given to the correct positioning of reinforcing steel and connections to
ensure that the correct amount of concrete cover is being obtained. Exceptional
vibrations in profile such as deep projections or protruding nibs and corbels used for
fixing purposes are installed separately into the mould.
2.4.3.3 Gang Casting
Gang casting is the term used to describe a modification of the wet casting
process which utilizes special mould configurations. Ganging is the process of
combining numbers of moulds into a unit assembly, generally width-wise. Gang moulds
allow the best use of the mechanical properties of mould dividers, reduce the amount of
structural support needed to the mould face and also allow a better utilization of the
available casting space. Gang casting usually allows concrete to be placed faster. Due to
the increased mass of the moulds compaction may require to be supplemented by
immersion-type vibrators.
The arrangements for tying gang moulds are simplified by the fact that the
pressure loading on each of the side members is counteracted by that of the adjacent unit.
It is usual to reduce the number of tie members by insertion of spacers which require
only that the external side formers are securely supported. The filling of gang moulds
requires careful control to ensure that dividing plates or intermediate moulds are not
subjected to differential loadings which could cause deflection and waver along the line
of the mould.
2.4.3.4 Stack Casting
The process of stack casting is something of a modification which can be applied
to flat and gang cast units of fairly regular section. In this process the gang mould is
filled and after hardening has taken place, the divider plates are drawn until the
appropriate depth of mould is set for next layer to be cast. The treatment of nosings and
chamfers requires attention and a parting agent in the form of a sheet material or painted
application must be provided prior to the second stack of casting being carried out. It is
essential at the time of each succeeding cast to ensure that the correct depth of cast
component is maintained.
Concrete pallets offer the precaster the opportunity of establishing an accurate
template for the stack casting process. Meantime, the precaster has found out that the
incorporation of through holes, barrels or the insertion of buried anchors allows for the
fastening of the mould sides in their second and subsequent positions also maintaining
correct casting thickness.
2.4.3.5 Battery Casting
The use of battery moulds has become increasingly popular in large panel
construction. This technique is employed for the manufacture of flat structural panels
and floor slabs as well as for featured and decorative cladding components. A wide
range of materials can be used in constructing the moulds and providing featured effects.
The mould principle employed is rather similar to that of suspended files in a filling
cabinet. Great amount of mechanical skill has been exhibited in the mechanization and
automation of the moulds used in the process. Basically the moulds consist of a series of
leaves or plates spaced apart by mould members which form the equivalent of the soffit
and stopends in the simple precast mould.
The basic component of a simple mould arrangement is the walkway against
which the back plate is erected. This back plate generally consists of a steel plate or
grillage of steel suitably clad to provide the sheathing face to one side of the first unit.
Care and attention is required in the assembly operations as it is obvious that should
cast-in fittings be attached to each side of the mould cell prior to casting the concrete
unit. Batteries of moulds allow a high density of casting to be carried in a given space.
The capital involved in providing even simple batteries is high but very considerable
savings can be made in space with resultant reduction in overhead costs.
2.5 Prefabrication Plant
The nature of prefabrication plant for a particular system of elements depends on
the type of elements to be produced, the desired output capacity and the conditions
particular to a region and a location at which the plant will operate. The planning of a
production system consists in a selection of methods and equipment to be employed,
plant layout design and preparation of procedures for its operation and management.
2.5.1 Types of Prefabrication Plant
Prefabricated elements and systems may be produced under different
organizational arrangements. The plant may act as an independent industrial venture that
supplies elements or group of elements to various building enterprises. It may operate as
an integral subunit of a building company which uses prefabrication as its main or only
construction method. It may also be established for a particular project at the building
site. The organization of the plant and the production employed there will depend very
much on these premises. It will depend on the required output, anticipate stability of
demand, availability of investment funds, local market if materials and labour and so on.
In a very broad term, prefabrication plants can be classified with relation to their typical
organization and technological aspects into three groups:
Regular or ‘permanent’ plant
Low investment or ‘field’ plant
Prefabrication on the building site
It is not always a prefabrication plant can be identified with one or another of the
categories. However, it is very often a plant may have some features that qualify it as a
permanent plant and others that typify it as a field plant. There were also cases when
onsite fabrication intended originally for a single project, developed into a large scale
independent plant.
2.5.1.1 Permanent Plant
A permanent plant is used when the volume and continuity of demand justify
high investment in production resources for labour savings, better quality of product and
more diversified production capacity. A permanent plant typically operates as an
independent venture or as a highly autonomous unit within a large parent company. The
main features of a permanent plant are:
Production takes place in an enclosed space and is therefore unaffected by
weather. Plant may operate in two or three shifts per day.
Production employs energy-intensive accelerated curing methods. Consequently,
moulds may be used two or three times per day.
Concrete and material handling devices are specifically adjusted components
according to specific requirements of a client.
Auxiliary production functions which means the preparation of reinforcement
and other fixtures, maintenance and transformation of mould are mostly done in
house.
It has own accounting, payroll and marketing functions.
It is expected that in time an increasing share of production and material
handling activities in a permanent plant will be fully automated.
2.5.1.2 Field Plant
Field plant is designated to perform the same production operations as a
permanent plant but with minimum investment and maintenance expenses. It uses
inexpensive production facilities and is more adaptable than the permanent plant to
changes in volume or nature of demand. In most cases, the plant operates within a parent
construction company which uses IBS components for its own projects. Field plant can
be employed in the most efficient manner in regions where ambient weather conditions
allow for year-round outdoor production of IBS elements. The main features of field
plant are:
Production takes place outdoors or under a light sun or rain roof shelter.
Therefore, the plant operates in daylight only and normally it is in one or one and
a half shifts.
No accelerated curing system is employed in this plant.
Inexpensive moulds and general-purpose construction equipment such as crane
and forklifts are used for the casting and handling of the IBS elements.
The plant platforms very auxiliary operation whereby most maintenance and
moderate mould adjustments, reinforcement and fixtures preparation, mould
production and mechanical work is ordered from outside.
As the plant operates within a framework of a parent contracting company, the
company also does all or most of the design and office work.
The field plants usually have higher direct labour requirements and more
difficulty in maintaining high quality standards compared to permanent plants. However,
under competent engineering and management, field plants can produce elements of
complicated shapes and excellent quality.
2.5.1.3 Fabrication on Building Site
Fabrication on a building site is carried out if the size of the project justifies the
considerable setup costs associated with precasting. The site precsting has the following
features:
Production takes place outdoors near the erection site.
Precasting is limited to selected elements, mostly membrane floor slabs, exterior
cladding, lintels and parapets. Simple moulds are used for casting which can
easily be dismantled and transferred from one site to another.
The auxiliary production operations such as the adjustment and repair of moulds,
reinforcement preparation, materials testing are provided from outside the plant.
Casting of elements is done with ready-mixed concrete or with concrete
produced onsite.
Demoulding of elements and other handling operations are performed with
general-purpose cranes that used also for other activities onsite.
Precasting is an integral part of the construction process onsite. It is therefore
performed under a general responsibility of the managerial personnel onsite.
Precasting on the building site may seem very attractive economically as it
obviates the need for a separate plant unit and saves transportation cost of elements to
the site. However, these savings can be realized only if the project is large enough to
absorb the setup costs of a production system onsite and the personnel onsite must have
enough managerial and technical knowledge to ensure efficient precasting and
satisfactory quality.
2.5.2 Design of Plant Facilities
For the planning purposes, it is convenient to divide the in-plant facilities into
four groups. The first group is direct production facilities, which affect the flow of
concrete through the prefabrication plant as shown in Figure 2.4. This group of activities
is the most dominant and determines the selection of equipment and facilities. Direct
production facilities include the activities of mixing of concrete and the moving of
concrete from mixing station to the moulds. Then, it is followed by casting of elements
in the moulds after the placement of reinforcement and fixtures. Curing and demoulding
works after the IBS elements are set. Finishing, patching and repairing of elements are
including in direct production facilities before hauling of elements from moulds to the
storage area takes place.
The second group of in-plant facilities is supporting facilities which include the
preparation of reinforcements, fixtures, inserts and finishes to be contained in the
element. Apart from that, maintenance of mechanical equipment, maintenance,
transformation and storage of moulds also come under supporting facilities. The third
group is offices which house the different administration, engineering and production
control activities. The fourth group is infrastructure which includes access roads, parking,
fences and gates.
Figure 2.4 : Main stages of concrete flow through a prefabrication plant
2.5.3 Plant Layout Design
Prefabrication plant layout design should provide convenient working conditions
for each function and an efficient flow of labour and equipment between the various
work areas. In general, there are thirteen principles that should be observed in the design
of plant layout.
Adequate space should be provided for each activity. Space allocation for
production activities must consider the physical dimensions of utilized
equipment, allow convenient and efficient performance of manual tasks
and leave room for storage materials and finished components
immediately associated with production. Space for office activities should
take into account the number of people employed, storage requirements
for plans and files and special equipment like drawing boards and
computers.
Adequate space for storage of materials such as aggregates, steel, window,
door frames, insulation, admixtures and fixtures. Moreover, adequate
storage space needed for equipment namely moulds, mechanical tools
and vehicles. It is essential to have an easy access to each item for
handling and maintenance purposes.
Adequate space for prefabricated elements with easy access of labour and
equipment to each elements as well as satisfactory loading conditions
near every element group.
An easy access and equipment to all work.
Proximity of location between activities with a strong functional
relationship
Easy flow of materials in the plant. This flow involves concrete transfer
from mixer to moulds and for other materials from their storage area to
the moulds. An easy flow also needed for the cast elements from the
moulds to the finishing stands or storage.
Shortest and most convenient transportation of elements from stockyard
to exit gate of the plant. Access road must be carefully planned and allow
two directional traffic.
Convenient hauling of materials from the gate to their respective storage
area or shed.
Maximum safety to the workers in equipment operation and materials
handling. This means that the routes of equipment movement should be
isolated if possible from the manual workstation.
Optimal physical conditions in terms of lighting, temperature, acoustics
and structuring of workstation.
Good visual control of line management over the work process.
An easy access and ample space for inspection and maintenance work of
all facilities and equipment in the plant.
Flexibility of layout for future extensions in each production department.
2.5.4 General Layout Pattern
The general layout pattern of a prefabrication plant is largely governed by its
division into different element casting lines. Apart form that, it is also governed by the
allocation of the concrete center, the production area and element storage area of each
completed element.
Normally, small production plant may be conducted in a single line, contained of
one shed or a compacted outdoor area and served by a single handling system. Such
production area may have a concrete mixing center adjacent to it on one side and storage
area on another side as shown in Figure 2.5a. In general, these functions are placed in
such a manner so that the concrete movement to the moulds and the element handling to
storage will be easiest and fastest.
On the other hand, different elements may be produced in different production
lines in larger plant. For instance, one line is made specifically for the production of
floor slabs, probably another line for the production of exterior wall and so on. Each line
will have its own element handling system either crane or conveyor. In some large plant,
there will be a separate concrete mixing center, curing chamber and storage for each line.
This separate system is usually more expensive in terms of investment, operation and
maintenance. It may be preferred if the production volume justifies or if the hauling of
concrete requires long transportation routes or a difficult access. However, sharing of
one or more of these functions with other lines is more practical and popular. This
system is shown in Figure 2.5b.
P – Production ofElements
B – Concrete MixingCentre
S – Storage ofElements
H – Heating chamber
Figure 2.5 : (a) Concrete centre, production area and storage area in direct
continuation
(b) Common concrete centre curing chamber and storage area for
two departments
2.6 Work Organisation
Generally, there are two alternatives of work organization for the production of
IBS elements. Under one alternative, all operations on the mould are performed by the
same crew. This means that after the preparation of the mould and casting of concrete
are completed, the crew will move to the next mould and starts to work on it from the
beginning and the process repeat for the succeeding moulds. Under the second
alternative, the total process is broken into several activities which are performed by
different crews with specialized tools and work methods.
2.6.1 All-purpose Team Method
All-purpose team method mostly used stationary moulds as illustrated in Figure
2.6. Each team performs all production activities on one mould and then proceeds to the
next mould. Such a multitask approach is usually less efficient in terms of labour, tools
and working space utilization. Furthermore, this method may create, as a casting cycle
of a day, some problems of coordination of element handling in the morning when all
crews start their shift by demoulding hardened element. The coordination of concrete
supply may pose a problem for the same reason when all crews progress at
approximately same pace. The coordination problems may be alleviated by starting
production crew at different hour. However, the production process will not be as rigid
in reality. The crew would be able to start striping or cleaning mould 2 while waiting for
concrete for mould 1. In fact, the crew may even prefer to prepare all three moulds for
casting before actually casting them.
The advantage of the comprehensive approach is the undivided responsibility of
the crew for the total production. The crew may set its own pace and work method and
be held responsible for its output as well as the quality of work. There is no dependence
between the different crew except the usage of handling and pouring equipment.
Therefore, this method of production is better adapted to the production of
heterogeneous elements in terms of shape and size.
Figure 2.6 : Production with all-purpose team method (two teams)
2.6.2 Workstation Method
The specialization method or workstation method requires division of the total
work into several tasks such as demoulding, mould preparation, casting and so on. All
the process is carried out by different crew as shown in Figure 2.7. In this method of
production, the balancing of work cycles of the various crews will ensure the full
employment of the production labour. The specialization method is therefore very
efficient in terms of crew and equipment usage. There are no waiting times since each
crew uses its own specialized type of equipment. The system is particularly efficient
with a movable production line where the moulds are moving from one workstation to
another and different tasks are performed between each of them. Although this system is
well suited to a movable production line, it can be employed also with static moulds and
crews moving from one mould to another.
The main limitation of the specialization method is its loss of efficiency in the
case of heterogeneous element. In such a case, it is very difficult to balance the work of
all crews and some idle time must be expected. This system is very sensitive to delays
due to malfunctioning of labour or equipment at any workstation as each crew depends
on the work performed by the former one.
The specialization method is probably most efficient with respect to labour and
equipment utilization. However, it is more constraining and therefore less motivating
with respect to production labour. It allows less room for initiative and less freedom for
remuneration of special effort or diligence.
Figure 2.7 : Production with workstation method (three shifts)
2.7 Simulation Overview
Simulation is a process of building a model that mimics reality. According to
Lanner Group (2000), simulation is imitating the operations of various kinds of real-
world facilities or processes, the process of designing a mathematical-logical model of a
real system and experimenting with this model on a computer.
The benefit of using simulation to visualize the system under investigation
increases the credibility of a project. Hence, there are many other benefits to be gained
through simulation modeling. These include:
- A greater understanding of the system being studied
- Improved communication of ideas
- Lower cost
- Ability to try many options quickly and easily
Simulation provides its users with an understanding of the system being modeled
while avoiding the consequences of working with a life system. Simulation will able to
predict or forecast the costs of building the proposed system. On top of that, it will
indicate the effect of the proposed system to the existing system.
Simulation allows the users to monitor the dynamics of a system under various
conditions. It is the only appropriate analysis technique when formal mathematical
methods cannot reflect the natural behavior of a system. Simulation provides:
- Risk reduction
- Greater understanding
- Operating cost reduction
- Capital cost reduction
- Ability to perform ‘what if’ analyses
- Implementation of optimum and best option.
CHAPTER 3
METHODOLOGY
3.1 Introduction
There are a few processes involved in carrying out this study. Basically there are
three steps involved in order to achieve the objectives of this study.
Step 1 : Data Collection
Step 2 : Modeling and Simulation
Step 3 : Data Analysis and Discussion
3.2 Data Collection
On site data collection is the most essential part of this study. The data that needs
to be collect is the production time of the IBS components namely beam and column.
The productivity or time required by the workers in performing each of the tasks in the
production of IBS components is based on real time observation and experience sharing
by the precast manufacturer.
3.2.1 Production Time
The production of the IBS components is carried out at the precast plant by a
qualified precaster. The production of IBS components basically can be divided into
three major stages namely preparation stage, casting stage and storage. The time needed
to complete these activities or production is clocked using stopwatch. The major stages
of production are illustrated in Figure 3.1.
SteelReinforcement
ConcreteSupply
Plates andSpiral LinksFabrication
Fixing ofRebar anddegreasing
ConcretePlacing
Treatment& Curing
Storage
MouldPreparation
PreparationStageCasting
StageInventory
Storage
Figure 3.1 : Production Stage
3.2.1.1 Preparation Stage
Preparation stage consists of steel reinforcement fabrication, steel plate
preparation, link fabrication and steel mould preparation at the first part. All these
activities are able to be carried out simultaneously. The preparation works of these four
elements can be carried at different places and using individual workstations.
The second part of work in preparation stage is to assemble all the parts prepared
earlier into an element for casting purpose. Fixing rebar process includes welding of four
main reinforcement bars with the spiral links and welding of steel plates to the
reinforcement bars to form a steel cage. Next, the steel cage is fit into the steel mould
and this will followed by degreasing process.
[Process improvement: Robotic welding]
3.2.1.2 Casting Stage
The casting process is constituted by two major activities which are concreting as
well as treatment and curing. The concrete supply is located near to the casting yard in
order to have an easy delivery of the wet concrete. The IBS component is demoulded
after it is kept for one day to ensure that the concrete is set. At the same time, the wet
IBS element will undergo a wet curing process.
Treatment process takes place after the IBS component is demoulded whereby it
is performed to touch up and level the surface of the component. It is followed by the
wet curing process again for another seven days before its undergo room-temperature
cured for another fourteen days. The curing process is to ensure the target mean strength
of the IBS component according to British Standard 8110.
[Process improvement: Using quick set cement on distributed casting]
3.2.1.3 Inventory Stage
Inventory stage is the last stage involved in the production of IBS component.
The completed component is sent to the storage area after twenty eight days of curing. It
is ready to be delivered to construction site for installation. It is crucial to maintain a
sufficient amount of completed components to ensure a continuous supply of IBS
components to the client. Nevertheless, if the completed components are over produced,
it will cause unnecessary problems.
[Process improvement: Database of inventory, Serial numbering]
3.2.2 Number of IBS Components
The total amount of IBS components needed to be produced is based on the
drawing shown in Figure 3.2. The amount of beam and column is extracted from the
drawing and with the assumption that it is constructed twenty houses per row.
Beam 2
Beam 1
Column
Figure 3.2 : Single Storey 100% IBS House Drawing
Copyright @ 2005 EBS
3.2.3 IBS Production Plant
The set up IBS plant is based on the production concept of workstation method.
There are a few assumptions made in this study such as raw material supply at the
beginning of the production and the supply of wet concrete during the casting process. It
is assumed that there is a continuous supply of the raw material such as steel bars, links
and plates which means that the production will be uninterrupted due to material
shortage. Secondly, the supply of wet concrete is also continuous as the concreting
process is required. The labours are always available during the production which means
the production will not be interrupted due to inconsistency of labours. Finally, machine
breakdown is neglected in this study.
There is an important constraint in the production of IBS component. The
constraint is the limited number of steel mould available for the production. The steel
mould is reusable and it is specially designed. The investment cost is very high and
therefore the precaster can only afford to a certain amount of this reusable steel mould.
The precast plant is a field plant where most of the operation is carried out
manually. The prefabrication plant consists of four main departments whereby it is
designed according to the convenience and sequence of the production process. The steel
fabrication workshop and concrete mixing centre is located next to the production lines
whereby the fabricated steel reinforcement can be easily transported to the production
line. In the prefabrication plant, there are two separate production lines which cater the
production of beam and column respectively. The third department is the treatment and
curing area. Lastly, there is a wide unshaded area for the storage of completed precast
components.
The number of workers needed in the production is based on the number of
workers observed during the site observation. The production plant works in at least one
shift a day which is equivalent to six hours and the maximum of three shifts per day
which is equivalent to eighteen hours. Six hours is the effective working hour of the
workers spent in the manufacturing work.
[Process improvement: Tower crane, Train]
3.3 Modeling and Simulation
With the collected data of the activities’ duration, a model is made using Witness
2001 software. Witness 2001 is a simulation software with a simple icon base set up and
the start up window of the software is shown in Figure 3.3. The main objective of the
simulation is to find out the optimum line of production set up with limited number of
steel mould available. Optimum production line is very much relies on the efficiency of
the production line and the number of resources required.
Therefore, time and resources are the main concern in the simulation. Time
means the overall time needed to complete the production of IBS components while
resources means the machinery and labour needed in completing the production in a
stipulated time.
Figure 3.3 : Witness 2001 Software Start Up Window
3.4 Data Analysis and Discussion
From the results of the simulation, it is interpreted to show the time needed to
complete the required number of IBS components for a medium size single storey
housing project ranging from one hundred to three hundred houses. Apart from that, the
amount of resources required is also interpreted from the results of the simulation.
Basically, there is a proposal of IBS pilot plant set up as the conclusion of this
project. Comparison and discussion are made based on each proposed production line in
terms of resources and time.
3.5 Research Methodology Flowchart
The flowchart is shown in Figure 3.4 which indicates the general procedures that
adopted in carrying out this study.
Flow chart of the research methodology
Identification of the research topic First stage and scopes of study
Objectives of Scope of Literature
Data Collection:Second stage
(i) Interview session(ii) Real time data collection
Third stage
Results and analysis
(i) Simulation is carried out based on the data obtained.(ii) Analysis and discussion is carried out based on the result of the
simulation.
Make conclusion
Figure 3.4 : Research Flowchart
Fourth stage
CHAPTER 4
DATA AND RESULTS
Curing Storage Area
4.1 Introduction
This chapter is about the data and results from the simulation. The first part is on
the data that observed from the precast plant. The data observed includes the layout of
the precast plant, time and activities involved in IBS elements production, operation
hour of the production plant as well as the number of IBS elements that need to be
produced. With these data, the model and simulation of the IBS production is created
using Witness 2001 software. The simulation results are considered as the second part of
this chapter. The simulation results indicate the time, resources and temporary storage
area required in the production plant. Based on the results from the outcome of
simulation, discussion and conclusion can be developed.
4.2 Precast Plant Layout
The IBS precast plant layout is based on EBS precast pilot plant. The layout of
the plant is shown in Figure 4.1
Beam Production LineSteel, Platesand Links
Fabrication.
Treatment&
Mould Assembly
Column Production Line
Figure 4.1 : IBS Precast Plant Layout
4.3 Activity Duration and Resources
Activity duration is the data measured using real time clocking at construction
site. It is the first part or prerequisite of the whole simulation. This means that the
simulation is unable to be carried without obtaining the activity duration of every
process involved in IBS component production. Logically, the summation of the every
activity’s duration include the travel time taken to move from one workstation to another
during the production will be the overall production time. This concept is just applicable
to simple and low volume of production. Nonetheless, the IBS production is a complex
and yet the number of production is large, therefore computer simulation will help in
determining the production time precisely and systematically especially for what if
situation. There are six activities involved in the whole IBS component production as
mentioned earlier in Chapter III.
4.3.1 Parts Preparation
Part preparation is the first activity in the whole IBS component production
process. Basically, they are four parts that need to be prepared namely cutting of
reinforcement bars, preparation of spiral links, fabricating of steel plates and assembling
of steel mould. The preparation raw material previous of these parts are not included in
this study.
IBS component production is standardized and modular in order to ease the
manufacturing work. Therefore, each beam and column required four reinforcement bars,
a spiral links, three steel plates and a steel mould. The task involved in preparing the
reinforcement bars is very simple whereby it is cut into the required length which is
3.4m and 6.8m for beam while 3.3m for column.
The preparation of spiral links takes a longer period of time and it can only be
done with the assistant of a spiral link machine. Steel plates are used for the connection
purpose between the IBS components during erection. Steel plate is cut into the required
dimension and fold to the required shape and weld to the main bars. Reusable steel
mould is used for casting and the steel mould is specially design where it is just need to
flip up the four hinged surface and clip on to complete the assembly work. The mould
needs to undergo oil treatment process to make sure that the IBS formwork components
can easily be strip off from the concrete during the demoulding process. The measured
time for each part is shown in Table 4.1.
Table 4.1 : Parts Preparation Time
4.3.2 Fixing of Reinforcement Bars
Fixing of reinforcement bars process is to combine all parts which were prepared
in the earlier stage. Basically, fixing of the reinforcement bars consists of two major
tasks. The first task is to weld the main reinforcement bars to the links. Both links and
reinforcement bars are welded at specific location just to make sure that the main
reinforcement bars are attached to the links to form a steel cage. The following task is to
fix the steel cage into the mould together with three steel plates at the middle as well as
the both ends of the component. The whole process will be completed in twelve minutes
with two skilled labours.
4.3.3 Degreasing
Parts Time Required (minutes) Labour
Reinforcement Bars 5 2 Unskilled
Links 27 1 Skilled
Steel Plates 15 1 Skilled
Mould 40 2 Skilled
The spiral links prepared in the earlier stage using the spiral link machine will
cause an oily and greasily surface to the links. The spiral link machine can only be
operated with the help of grease in order to spiral the links. Therefore, the fabricated
spiral links is in oily and greasily condition. Oily and greasily surface of links will affect
the bonding between concrete and the reinforcement. In order to overcome this problem,
degreasing process is required before the concreting process. Hand spray contains of
water and air is used to blow away the grease and oil. The degreasing process takes ten
minutes with one unskilled labour.
4.3.4 Concreting
Placing the concrete into the mould would be considered as a major process in
IBS component production. It is done at a separate workstation next to degreasing area.
The concrete used is supplied by ready-mixed concrete supplier whereby it is assumed
that the supply of concrete is continuous during the production.
The casting work is carried out on top of the vibrating table which means that the
compaction work is performed concurrently during concreting. The placing of concrete
into the mould is done manually with the help an arm in directing the concrete flows into
the mould from the mixer lorry. The whole concreting process required two skilled
workers where one of them in charge in placing the concrete while the other one will
operate the vibrating table for compaction work. The whole process can be completed in
24 minutes and the completed IBS component is sent to the curing area before it is
demoulded.
4.3.5 Demoulding and Inspection
The demoulding and inspection process is carried after twenty four hours of wet
curing with gunny sacks. After the demoulding work, there will two separate items
remain. One of them is the completed IBS component whereby it will undergo
inspection and quality control process. Marking of the completed IBS component is the
final procedure before it is sent to inventory area. The other remaining item is the steel
mould, it is sent to another workstation for cleaning and reassembling process. The
demoulding, inspection and marking process needs twenty four minutes and there is only
one unskilled labour required.
4.3.6 Cleaning and Reassembling of Mould
The steel mould is reusable however it needs to go through cleaning and
reassembling process before it is ready to be reused. The cleaning and demoulding
process takes forty minutes and done by one unskilled worker.
The duration used for each activity is shown in Table 4.2.
Table 4.2 : The Duration of Every Activity
Activity Time (Mins) Labour Equipment
Main Bars Preparation 5 2 unskilled 1 unit of Cutter
Plates Fabrication 15 1 skilled1 set of Cutter and Welding
Equipment
Spiral Links
Preparation27 1 skilled
1 unit of Spiral Link
Machine
Steel Mould Assembly 40 2 skilled Hand Tools
Fixing Rebar 12 2 skilled 1 unit of Welding Machine
Degreasing 10 1 unskilled 1 unit of Spray
Concreting 24 2 skilled 1 unit of Vibrating Table
Demoulding and
Inspection25 1 unskilled Hand Tools
Mould Cleaning and
Reassembling40 1 unskilled Hand Tools
4.4 IBS Beam and Column Required
The IBS beam and column needed is extracted from a 100% IBS house as shown
in Figure 3.2. The total amount IBS beam and column needed for 100, 200 and 300
houses is shown in Table 4.3.
Table 4.3 : Total Amount of IBS Element
4.5 Working Time and Constraint
The effective working time for IBS component production is six hours per shift
which is equal to 360 minutes. The prefabrication plant works in three shifts per day in
maximum and one shift per day in minimum. Number of steel mould available is the
major constraint in the production as the investment cost is extremely high. As a result,
the simulation is carried out to its optimum based on the number of steel mould available.
The effective working hour and the number of mould are shown in Table 4.4 and 4.5
IBS Element
No. of House
Beam 1
200 x 300 x
3400
Beam 2
300 x 300 x
6800
Column
300 x 300 x
3300
100 1745 805 735
200 3490 1610 1470
300 5235 2415 2205
Number of Shift Time (minutes)
1 360
2 720
3 1080
respectively.
Table 4.4 : Effective Working Hour
Table 4.5 : Number of Steel Mould Available
4.6 Modeling
The whole process of IBS component production is modeled using Witness 2001
software Basically, there are two different production lines consist of beam production
line and column production line. This model is shown in Appendix A.
They are four entities used in the modeling of IBS production namely Part,
Conveyor, Machine or Workstation, Integer and Buffers. Each entity has their own built-
in function and user defined characteristics such as time used for processing the
components, the maximum number of supply available, detention time, maximum
storage and so on. Figure 4.2 shows the all the entities used in the modeling of IBS
production.
(a) (b) (c)
IBS Component Number of Steel Mould
Beam 125
Column 75
(d) (e)
Figure 4.2 (a) Part Element
(b) Buffers Element
(c) Integer
(d) Conveyor Element
(e) Machine Element
Parts represent the supply of raw materials and it is also represent the source of
the whole modeling. Machines or workstations represent the process or activity carried
out during the production. Integer is used in counting the completed component
manufactured in the simulation. The transportation of the parts from one workstation to
another in the model is represented by conveyor belts with the duration of five minutes.
Buffers in the model represent the temporary store required to keep the parts.
Buffers are needed in IBS production because of two reasons. The first reason is to
eliminate the blocking of the production line and to purposely keep the component
before it can be further process. The second reason is to purposely keeping the
component after the casting process whereby the IBS component can only be demoulded
after twenty four hours to ensure that the component is set and to carry out wet curing
process at the mean time. The wet curing process creates a great impact to the whole
production process especially with the limited number of steel mould.
Every entity has their respective user defined interface where it can be set and
defined according to the user’s needs. Basically, all the items that need to be defined by
the user are located at General which contains the name of the entity, the time or
duration of the activity, quantity of the entity and so on. The dialog box for Parts and the
description of the interface are shown in Figure 4.3 and Table 4.6 respectively.
Figure 4.3 : Part Detail Dialog Box
Table 4.6 : Part Detail
Buffer’s dialog box and its description are show in Figure 4.4 and Table 4.7.
Information Description
Inter Arrival Time Time between arrival
Lot Size Number that arrive together
Maximum Arrival Maximum number that can arrive
throughout a simulation run
First Arrival At Time first one arrives in the model
Active The element is always available
To… The location that the Parts are sent
Figure 4.4 : Buffer Detail Dialog Box
Table 4.7 : Buffer Detail
Figure 4.5 Dialog box of Conveyor entity and the description is shown in Table 4.8.
Information Description
Maximum CapacityMaximum number of Parts (entities) can
be stored
Input OptionPosition at which Part (entity) enters the
Buffers
Output OptionPosition from which part/entity will leave
the buffer
Option – NoneThe Buffer behaves as a normal passive
Buffer and a Part (entity) can be removed
at any time by another Element
Figure 4.5 : Conveyor Detail Dialog Box
Table 4.8 : Conveyor Detail
Figure 4.6 Dialog box of Machine entity and Table 4.9 shows the description.
Figure 4.6 : Machine / Workstation Detail Dialog Box
Table 4.9 : Machine / Workstation Detail
Information Description
Length PartsUses the number of Part (entity) positions
on the Conveyor to define the length of the
conveyor
Maximum CapacityMay be less than the Part (entity) length
due to operating constraints
Index TimeThe time required to index or move one
position in the conveyor
Information Description
Input Rule Bring in the part or entity
Cycle Time Duration Time taken to process the parts (entities)
Output RuleWhere the part or entity is sent to after the
machine or activity has finished processing
Figure 4.7 Dialog box of Integer
Figure 4.7 : Dialog Box of Integer
4.6.1 IBS Production Modeling
The modeling of IBS component production begins from the preparation of parts
until the demoulding process. Transportation process after the demoulding of completed
IBS components are excluded from this study. Parts consist of Bars, Links, Plates and
Moulds are used at the beginning of the modeling as the supply raw material for the
production. The prepared parts are sent by railed trolley to their respective buffers before
they are processed at FixReWeld. The FixReWeld workstation which carried out fixing
of reinforcement bars into a component will extract one part from each buffer located
before the workstation.
Next, the component is transported with railed trolley for degreasing process at
the Degreasing workstation. After degreasing work, the component is sent to Concreting
workstation for placing of concrete by using crane. This will be followed by sending the
cast-components by tower crane to DemouldBuffers for twenty four hours detention
before the demoulding process at DemouldInspec workstation. However, the detention
is set according to the effective working hour and the detention will have a greatly effect
the production as the production may be interrupted due to insufficient number of mould.
The detention varies and it is depends on the shift of production. It will be set at six
hours for one shift of production; twelve hours for two shifts and eighteen hours for
three shifts.
After the demoulding process, mould is transported by using side-loader forklift
to ReuseMould workstation for cleaning and assembling purpose before it is reused.
The process repeat until it achieved the required number of IBS element. It is a trial and
error approach to fix the number of resources in the most optimum way to complete the
required IBS components within the targeted time.
The transportation of components or parts is modeled by Conveyor element. The
time required to travel from one workstation to another is five minutes. However, the
traveling time is set at fifteen minutes in the model whereby the additional time is used
for checking and quality control purposes.
The running of the simulation is shown in Appendix B.
4.7 Result
The result of the simulation is about the time taken to complete the production of
IBS beams and columns to supply for the construction of medium size single storey
housing project ranging from one hundred to three hundred houses. The production time
is simulated based on two months and three months targeted duration. Other resources
such as number of worker and machinery are varying according to the duration of
production. There is only one lane of conveyer belt link between each workstation and
the value shows in bracket in each table means the buffer stock.
The results also imply the most optimum line of production with limited steel
mould at its fixed resources. In fact, there are three important aspects to be focused on
the simulation results which are the time and resources used for the production as well as
the area required to keep the inventory.
4.7.1 Two Months Production Time
The first targeted time of IBS component production is two months. The
production is carried out in between one shift to three shifts to meet the supply of one
hundred to three hundred houses. The detail of the simulation result and resources are
shown in Table 4.10.
Table 4.10 : Two Months Production Resources and Time
4.7.2 Three Months Production Time
Three months is another targeted time for IBS component production in this
simulation. From this simulation, it is clearly shown that the set up of the production line
especially in terms of resources is slightly different from the two months production
time. The detail of the simulation results and resources are shown in Table 4.11.
Table 4.11 : Three Months Production Resources and Time
Workstation/
Resource
100 Houses 200 Houses 300 Houses
Beam Column Beam Column Beam Column
Bar 1 1 1 1 1 1
Plate 3 2 3 2 3 2
Link 4 2 4 2 4 2
Mould 5 2 5 2 5 2
Fixing Rebar 2 1 2 1 2 1
Degrease 2 1 2 1 2 1
Concreting 3 (63) 2 3(18) 2 3 2
Demould 4 (45) 1 (70) 4 (90) 1 (70) 4 (108) 1 (70)
Clean Mould 5 2 5 2 5 2
Time Allowed 21600 (1 Shift) 43200 (2 Shifts) 64800 (3 Shifts)
Actual Time
(Beam)20851 (58 days) 41611 (58 days) 75547 (70 days)
Actual Time
(Column)18821 (53 days) 37556 (53 days) 56291(53 days)
Workstation/
Resource
100 Houses 200 Houses 300 Houses
Beam Column Beam Column Beam Column
Bar 1 1 1 1 1 1
Plate 2 1 2 1 2 1
Link 3 1 3 1 3 1
Mould 4 1 4 1 4 1
Fix Rebar 2 1 2 1 2 1
Degrease 1 1 1 1 1 1
Concreting 2 (84) 1 2 (54) 1 2 (24) 1
Demould 3 (30) 1 (9) 3 (60) 1 (18) 3 (90) 1 (27)
Clean Mould 4 1 (62) 4 1 (50) 4 1 (45)
Time Allowed 32400 (1 Shift) 64800 (2 Shifts) 97200 (3 Shifts)
Actual Time
(Beam)31047 (87 days) 62007 (87 days) 92967 (87 days)
Actual Time
(Column)27347 (76 days) 57467 (80 days) 87587 (82 days)
4.7.3 Contingency Plan
There is an additional simulation done whereby the production is targeted to be
completed in a month time. However, number of mould has increased to one hundred
units for column and three hundred units for beam. One month production is simulated
as contingency plan to cater for a sudden high demand of IBS component. The detail
simulation results and its resources used are shown in Table 4.12.
[Process improvement: Increase Number of workstation]
Table 4.12 : Contingency Plan Resources and Time
CHAPTER 5
DISCUSSION
5.1 Introduction
The main purpose of this simulation is to find out the most efficient and optimum
production line set up of a precast plant to cater the production of IBS elements required
for a medium size single storey housing project between within a stipulated time of two
months and three months. IBS elements in this context mean IBS column and IBS beam.
Workstation/
Resource
100 Houses 200 Houses 300 Houses
Beam Column Beam Column Beam Column
Bar 2 1 2 1 2 1
Plate 5 4 5 4 5 4
Link 9 2 9 2 9 2
Mould 14 5 14 5 14 5
FixRebar 4 2 4 2 4 2
Degrease 4 2 4 2 4 2
Concreting 8 2 (59) 8 2 (29) 8 2
Demould 7 (90) 3 (30) 7 (180) 3 (60) 7 (270) 3 (90)
CleanMould 10 (177) 4 10 (87) 4 10 4
Time Allowed 10800 (1 Shift) 21600 (2 Shifts) 32400 (3 Shifts)
Actual Time
(Beam)9941 (28 days) 20861 (29 days) 32165 (30 days)
Actual Time
(Column)9267 (26 days) 18443 (26 days) 27979 (26 days)
The most efficient and optimum line of production is governed by a constraint which is
the number of steel mould available. During the simulation, it is carefully monitored to
make sure that the production is smooth and can be completed in the targeted time.
5.2 Discussion
Two months and three months are the targeted production and basically there are
two kinds of production line set up. Two months production line set up is difference
from three months production line set up in terms of resources employed. On top of that,
the production is operated in one shift to three shifts basis whereby the production of
IBS elements for one hundred houses is in one shift, two hundred houses in two shifts
and three hundred houses in three shifts. No matter how the production line is, the
number of steel mould available is still the same for both production lines set up. They
are one hundred twenty five units of steel mould for beam and seventy five steel mould
for column.
From the results of the simulation, there are three important aspects that need to
be further discussed. The first aspect is the time used in producing the required IBS
components. The second aspect is about the resources allocated and finally is about the
storage area required for temporary keeping of material or inventory.
5.2.1 Time
Time is the essence in IBS component production and construction industry
generally. It is very important that the precaster to complete the production of the
required number of IBS components in time in order to avoid any delays on the
transportation schedule and the erection work schedule at site. The production time
needed to complete the production of required IBS components for two and three
months targeted time is shown in Table 5.1 and Table 5.2.
Table 5.1 : Two Months Targeted Production Time
From Table 5.1, it is obvious that the actual time used to produce the required
number of IBS column to supply for the construction of one hundred to three hundred
houses is below the targeted time. However, the production time of IBS beam
component to supply for three hundred houses is over the targeted time. The time needed
to complete the production of IBS beam for three hundred houses is seventy days. It can
be concluded that beam production line has reached it maximum capacity of production
whereby this production line set up is only able to produce 6549 units of beam sixty
days and work in three shifts. The actual production time maintained the same although
the resources are increased. This shows that the production fail to complete within the
targeted time because of insufficient number of steel mould.
The impact of insufficient steel mould becomes more critical when the
production is carried out more than two shifts. It is because three shifts production
required longer period of detention time for the mould to stay at the setting area
(DemouldBuffer) before it can be demoulded. The production is sometimes interrupted
as there is no steel mould supply due to the longer detention time. For column’s
production line, it seems to be well performed as all the required IBS columns can be
produced within the targeted time.
Table 5.2 : Three Months Targeted Production Time
Time100 Houses (1 Shift) 200 Houses (2 Shifts) 300 Houses (3 Shifts)
2505
Beams
735
Columns
5100
Beams
1440
Columns
7550
Beams
2205
Columns
Target
(60 days)21600 min 43200 min 64800 min
Actual
(Min)20851 18821 41611 37556 75547 56291
Actual
(Day)58 53 58 53 70 53
Time100 Houses (1 Shift) 200 Houses (2 Shifts) 300 Houses (3 Shifts)
2505
Beams
735
Columns
5100
Beams
1440
Columns
7550
Beams
2205
Columns
Target
(90 days)32400 min 64800 min 97200 min
Actual
(Min)31047 27347 62007 57467 92967 87587
Actual
(Day)87 76 87 80 87 82
From Table 5.2, it shows that both production lines are able to complete the
production within the targeted period of time. In fact, the production is completed at
least three days before deadline for beam and at least eight days before deadline for
column.
5.2.2 Resources
The resources such as number of labour and machinery used in the production
vary between two months and three months targeted production line set up. Definitely,
the production line set up for two months has a greater number of resources compared to
three month production line set up.
The determination of which resources needed to be increased is very important
and the effectiveness on the increased resources can be determined from this simulation.
The resources suggested for two months production line is shown in Table 5.3 and Table
5.4 while for three months production line is shown in Table 5.5 and Table 5.6.
Table 5.3 : Two Months Beam Production Line Resources
Activity / ProcessLabour
(1 Shift)Equipment / Machinery
Main Bars Preparation 2 unskilled 1 unit of Cutter
Plates Fabrication 3 skilled3 sets of Cutter and Welding
Equipment
Spiral Links Preparation 4 skilled 4 units of Spiral Link Machine
Steel Mould Assembly 10 skilled Hand Tools
Fixing Rebar 4 skilled 2 units of Welding Machine
Degreasing 2 unskilled 2 units of Spray
Concreting 6 skilled 3 units of Vibrating Table
Demoulding and Inspection 4 unskilled Hand Tools
Mould Cleaning and Reassembling 5 unskilled Hand Tools
Table 5.4 : Two Months Column Production Line Resources
Table 5.5 : Three Months Beam Production Line Resources
Table 5.6 : Three Two Months Column Production Line Resources
From the above tables, it is obvious that those two months production line
Activity / ProcessLabour
(1 Shift)Equipment / Machinery
Main Bars Preparation 2 unskilled 1 unit of Cutter
Plates Fabrication 2 skilled2 sets of Cutter and Welding
Equipment
Spiral Links Preparation 2 skilled 2 units of Spiral Link Machine
Steel Mould Assembly 4 skilled Hand Tools
Fixing Rebar 2 skilled 1 unit of Welding Machine
Degreasing 1 unskilled 1 unit of Spray
Concreting 4 skilled 2 units of Vibrating Table
Demoulding and Inspection 1 unskilled Hand Tools
Mould Cleaning and Reassembling 2 unskilled Hand Tools
Activity / ProcessLabour
(1 Shift)Equipment / Machinery
Main Bars Preparation 2 unskilled 1 unit of Cutter
Plates Fabrication 2 skilled2 sets of Cutter and Welding
Equipment
Spiral Links Preparation 3 skilled 3 units of Spiral Link Machine
Steel Mould Assembly 8 skilled Hand Tools
Fixing Rebar 4 skilled 2 units of Welding Machine
Degreasing 1 unskilled 1 unit of Spray
Concreting 4 skilled 2 units of Vibrating Table
Demoulding and Inspection 3 unskilled Hand Tools
Mould Cleaning and Reassembling 4 unskilled Hand Tools
Activity / ProcessLabour
(1 Shift)Equipment / Machinery
Main Bars Preparation 2 unskilled 1 unit of Cutter
Plates Fabrication 1 skilled1 set of Cutter and Welding
Equipment
Spiral Links Preparation 1 skilled 1 unit of Spiral Link Machine
Steel Mould Assembly 2 skilled Hand Tools
Fixing Rebar 2 skilled 1 unit of Welding Machines
Degreasing 1 unskilled 1 unit of Spray
Concreting 2 skilled 1 unit of Vibrating Table
Demoulding and Inspection 1 unskilled Hand Tools
Mould Cleaning and Reassembling 1 unskilled Hand Tools
required a higher number of resources in production. The higher number of resources
will help in reducing the overall production time. However, there is a cut off point where
the production time will not be reduced even though the number of resources increased.
This is due to the constraint applied in both production line set up which is the limited
number of steel mould available.
The production cost is absolutely higher for two months production line where
more equipments and labours are needed in the manufacturing. Table 5.7 and Table 5.8
show the overall resources needed in two months and three months production line
respectively.
Table 5.7 : Two Months Production Line Overall Resources
Table 5.8 : Three Months Production Line Overall Resources
The difference of labour between two months and three months production lines
Activity / ProcessLabour (1 Shift)
Equipment / MachinerySkilled Unskilled
Main Bars Preparation - 4 2 units of Cutter
Plates Fabrication 5 -5 sets of Cutter and Welding
Equipment
Spiral Links Preparation 6 -6 units of Spiral Link
Machine
Steel Mould Assembly 14 - Hand Tools
Fixing Rebar 6 - 3 units of Welding Machine
Degreasing - 3 3 units of Spray
Concreting 10 - 5 units of Vibrating Table
Demoulding and Inspection - 5 Hand Tools
Mould Cleaning and
Reassembling- 7 Hand Tools
Total 41 19
Activity / ProcessLabour (1 Shift)
Equipment / MachinerySkilled Unskilled
Main Bars Preparation - 4 2 units of Cutter
Plates Fabrication 3 -3 sets of Cutter and Welding
Equipment
Spiral Links Preparation 4 -4 units of Spiral Link
Machine
Steel Mould Assembly 10 - Hand Tools
Fixing Rebar 6 - 3 units of Welding Machine
Degreasing - 2 2 units of Spray
Concreting 6 - 3 units of Vibrating Table
Demoulding and Inspection - 4 Hand Tools
Mould Cleaning and
Reassembling- 5 Hand Tools
Total 29 15
is twelve persons for skilled labour and four persons for unskilled labour. There is also a
great difference for number of cutter and welding machine used to fabricate steel plates
for both production set up.
Besides that, spiral links machine and vibrating table also show a significant
different between both production lines. In fact, these three activities have a great effect
on the overall production time whereby the overall production time differs due to
changes in resources for these three activities. Therefore, those three activities can be
considered as the critical activity for the production.
The number of resources proposed for two months and three months production
line as shown in Table 5.7 and Table 5.8 can be modeled and simulated for four months
until one year targeted production time. Definitely, the working hour will greatly
reduced whereby the production may only be carried out in one shift.
5.2.3 Inventory Storage Area
The production plant needs to have a temporary storage area to temporarily store
the inventory before it can be further processed. For the production of IBS component, it
is a must to allocate a space to keep the wet IBS component until it is set and ready to be
demoulded. The setting process time is quickened by using heat or certain chemical
admixtures. Nonetheless, this production line is using natural setting which takes about
one day.
Apart from that, the production plant also needs to allocate a space normally an
open air area to keep the completed IBS components before there are transported to the
construction site. From the simulation, it shows that there must be some empty spaces
required during the production. The areas needed based on the number of IBS
components to be stored have been identified from the simulation and it is shown in
Table 5.9 and Table 5.10 for two months and three months production line set up.
Table 5.9 : Storage Area Required for Two Months Production Line
Table 5.10 : Storage Area Required for Three Months Production Line
The value shown in Table 5.9 and Table 5.10 means the number of IBS
components either beam or column that need to be kept temporarily before the activity
or process. The production plant has to allocate the empty space for temporary storage of
inventory based on the greatest value shown in the table.
From the result, both production lines set up plan required an area at the
beginning of the production process to store the parts or raw materials of the IBS
components. On top of that, additional space needed in two months production line is
near to the vibrating table where concreting is carried out and the area must be able to
store sixty three units of beam. Besides that, there must a space to keep the wet IBS
Activity1 Shift 2 Shifts 3 Shifts
Beam Column Beam Column Beam Column
Fixing Rebar Parts Storing
Concreting 84 - 54 - 24 -
Demoulding and
Inspection30 9 60 18 90 27
Mould Cleaning
and Reassembling- 62 - 50 - 45
Activity1 Shift 2 Shifts 3 Shifts
Beam Column Beam Column Beam Column
Fixing Rebar Parts Storing
Concreting 63 - 18 - - -
Demoulding
and Inspection45 70 90 70 108 70
components before it is set and demoulded. The area must be adequate to keep one
hundred and eight units of beam and seventy units of column.
For three months production line set up, the production plant needs to prepare
three empty spaces near to the vibrating table, demoulding area and fixing of rebar’s
workstation. The empty space near to the vibrating table must be able to accommodate
eighty four units of beam while at the demoulding area, the space must be sufficient to
store ninety units of beam and twenty seven units of column. Finally, an area to store
sixty two units of column at the demoulding and reassembling is required.
5.3 Contingency Plan
A contingency plan also generated from the simulation of IBS production in order
to cater for the some uncertainty or unexpected high demand of IBS components. The
contingency plan is to complete the production of IBS beams and columns for medium
size single storey housing project in one month targeted time. However, the amount of
steel mould constraint applied in earlier production line set up is eliminated from this
contingency plan. The number of steel mould suggested for the contingency plan is three
hundred units for beam and one hundred units for column.
Generally, the set up of contingency production line will incur more cost than the
two months and three months production set up as the number resources increased
dramatically in order to meet the one month targeted production time. Further discussion
is focused on the time, resources and inventory storage area.
5.3.1 Time
Time is the main concern in this simulation and it is the most challenging and
difficult criteria to be achieved in one month production line set up. Table 5.11 shows
Time100 Houses (1 Shift) 200 Houses (2 Shifts) 300 Houses (3 Shifts)
2505
Beams
735
Columns
5100
Beams
1440
Columns
7550
Beams
2205
Columns
Target
(30 days)10800 min 21600 min 32400 min
Actual
(Min)9941 9267 20861 18443 32165 27979
Actual
(Day)28 26 29 26 30 26
the time needed to complete the production based on one month targeted time.
Table 5.11 : One Month Targeted Production Time
From Table 5.11, the time needed to complete IBS beam element is between
twenty eight to thirty days while for IBS column element is twenty six days. The
production time is very much depends to the resources allocated for each process in the
production.
5.3.2 Resources
Substantial resources have been employed in this contingency plan. The
resources employed according to beam and column are shown in Table 5.12 and Table
5.13. The overall resources required are shown in Table 5.14.
Table 5.12 : One Month Beam Production Line Resources
Table 5.13 : One Month Column Production Line Resources
Activity / ProcessLabour
(1 Shift)Equipment / Machinery
Main Bars Preparation 4 unskilled 2 units of Cutter
Plates Fabrication 5 skilled5 sets of Cutter and Welding
Equipment
Spiral Links Preparation 9 skilled 9 units of Spiral Link Machine
Steel Mould Assembly 28 skilled Hand Tools
Fixing Rebar 8 skilled 4 units of Welding Machine
Degreasing 4 unskilled 4 unit of Spray
Concreting 16 skilled 8 units of Vibrating Table
Demoulding and Inspection 7 unskilled Hand Tools
Mould Cleaning and Reassembling 10 unskilled Hand Tools
Activity / ProcessLabour
(1 Shift)Equipment / Machinery
Main Bars Preparation 2 unskilled 1 unit of Cutter
Plates Fabrication 4 skilled4 sets of Cutter and Welding
Equipment
Spiral Links Preparation 2 skilled 2 units of Spiral Link Machine
Steel Mould Assembly 10 skilled Hand Tools
Fixing Rebar 4 skilled 2 units of Welding Machine
Degreasing 2 unskilled 2 units of Spray
Concreting 4 skilled 2 units of Vibrating Table
Demoulding and Inspection 3 unskilled Hand Tools
Mould Cleaning and Reassembling 4 unskilled Hand Tools
Beam production line required a greater number of resources as beam required a
bigger amount in the production. From the comparison between Table 5.12 and 5.13,
most of the resources employed in beam production is double compared to three months
production line set up. Concreting is the most critical activity it has a four times
increased in beam production line compared to column production line.
Table 5.14 : One Month Production Line Overall Resources
Activity / ProcessLabour (1 Shift)
Equipment / MachinerySkilled Unskilled
Main Bars Preparation - 6 3 units of Cutter
Plates Fabrication 9 -9 sets of Cutter and Welding
Equipment
Spiral Links Preparation 11 -11 units of Spiral Link
Machine
Steel Mould Assembly 38 - Hand Tools
Fixing Rebar 12 - 6 units of Welding Machine
Degreasing - 6 6 units of Spray
Concreting 20 - 11 units of Vibrating Table
Demoulding and Inspection - 10 Hand Tools
Mould Cleaning and
Reassembling- 14 Hand Tools
Total 90 36
From Table 5.14, the resources used in the contingency plan increased
dramatically compared to two months or three months production line set up resources.
From the comparison between Table 5.7 with Table 5.14, the resources have increased
doubly compared to two months production line set up. The resources have increased to
almost three folds for one month production line set up compared to three months
production line set up. It can be conclude that with the increased in resources and
number of steel mould, the production time is able to be shortened to one month.
5.3.3 Inventory Storage Area
The area required to temporarily keep the inventory is larger in the contingency
plan compared to two months or three months production line set up plan. Basically
there are four areas needed to store the inventory where the first area is near to the fixing
rebar workstation whereby it is used to keep the steel bars, plates and spiral links.
However, the other three temporary storage areas are required at the end of the
production process. Table 5.15 shows the storage area required for one month
production line set up.
Table 5.15 : Storage Area Required for One Month Production Line
From the results, an empty space required near to the concreting area for column
production line. It has to accommodate for about fifty nine columns. Demoulding and
inspection workstation also required an empty space to keep for about two hundred
seventy beams and one hundred eighty columns. An area needed to store approximately
one hundred seventy seven beams is needed at the mould cleaning and reassembling
Activity1 Shift 2 Shifts 3 Shifts
Beam Column Beam Column Beam Column
Fixing Rebar Parts Storing
Concreting - 59 - 29 - -
Demoulding and
Inspection90 30 180 60 270 90
Mould Cleaning
and Reassembling177 - 87 - - -
workstation.
Three shifts working time has the highest number of IBS elements to temporarily
store because it has the longest detention time before the IBS components can be
demoulded.
CHAPTER 6
CONCLUSION AND RECOMMENDATION
6.1 Conclusion
From this study, there are three significant conclusions can be drawn. There are:
(i) Optimum production line set up has been proposed to complete the
production of IBS beam and column required for the construction of medium
sized single storey IBS housing project within two months and three months
time with limited number of reusable steel mould.
(ii) Contingency production line set up with increase number of reusable steel
mould to produce the amount of IBS beam and column required for the
construction of a medium size of single storey IBS housing project in one
month time has been proposed.
(iii) Number of resources such as labour, machinery, tool and storage area
required in the production plant has been determined.
6.2 Recommendation
It is found out there are some fragmentary of this study where it can be further
improved in the future. The recommendations for future study are:
(i) An analysis of cost based on the proposed production set up can be
determined in order to indicate the budget required for the plant set up
(ii) Production schedule can be developed using computer software such as
Microsoft Project, Primavera or Artimes in order to compare the production
time produced from the simulation.
(iii) Production process improvement can be adopted in the production such as
using of automation or robotic, quick set cement and transportation between
workstations.
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Production Line Modeling
Production Line Modeling (Run)
One Month Production Line Set Up
Two Months Production Line Set Up
Three Months Production Line Set Up