i
INTEGRATING CONSTRUACTABILITY INTO THE DESIGN PROCESS
WOON KAI SIONG
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
November, 2006
iii
To my beloved mother and father
iv
ACKNOWLEDGEMENT
First of all, I would like to express my sincere appreciation to my project
supervisor, Ir. Dr. Rosli Mohamad Zin of the Faculty of Civil Engineering, Universiti
Teknologi Malaysia, for his generous advice, patience, guidance and encouragement
during the years of my study.
I would like to express my sincere thanks to all the architect and civil
engineers who generously spent their precious time to participate the interview of my
project data collection and comment to my work. Their opinions and comments are
useful indeed. My seniors and friends, who have provided assistance in arranging the
interviews and at various occasions, also deserve my special thanks.
Finally, I am most thankful to my parents and family for their support and
encouragement given to me unconditionally in taking this project report.
Without the contribution of all those mentioned above, this work would not
have been possible.
v
ABSTRACT
Constructability is an important element in building project’s design phase,
where designers’ personnel play a prominent role to enhance it. Several researchers
found that failure of design professional to consider constructability during the
design phase can result design reworks, contract changes, delay, increase of cost, and
even legal entanglement and claims. The focus of this study is establishment and
integration of constructability principles into the current building’s design process.
Therefore, the objectives of this study are to determine the local construction
industry’s current design process, in order to propose an integration of design
constructability review process to that existing design process model, and develop a
building design constructability checklist. There are three distinct phases of this
study: phase 1 involves literature review and preliminary interview; phase 2 consists
of structured interviewing with design professional experts and design process
models development; phase 3 comprises of constructability principles integration and
the checklist development. The data flow diagram (DFD) is adopted in this study to
model those design process flow. Finally, the outcomes of this study are
establishment of general building design process model, constructability integrated
building design process model and constructability checklist. This checklist acts as a
tool, where it is integrated with constructability principles, used for constructability
enhancement of the design. However, due to the limitation of time, only a foundation
design constructability checklist is developed.
vi
ABSTRAK
Kebolehbinaan merupakan salah satu elemen yang penting pada perinkat
rekabentuk suatu projek bangunaan, di mana para pereka memainkan peranan yang
penting untuk meningkatkan kebolehbinaan rekabentuk itu. Beberapa ahli
penyelidikan
mendapati
bahawa
kegagalan
pereka
mempertimbangkan
kebolehbinaan pada fasa rekabentuk suatu projek boleh menyebabkan perulangan
kerja, perubahan kontrak, penundaan, pengingkatan kos, kekusutan undang-undang
dan penuntutan ganti rugi. Fokus kajian ini ialah menubuhkan dan mengintegrasikan
prinsip-prinsip kebolehbinaan ke dalam proses rekabentuk banguanan. Maka,
objectif kajian ini adalah pengenalpastian proses rekabentuk bangunan tempatan
yang semasa ini, supaya ia dapat dicadangkan untuk diintegrasikan dengan proses
penilaian kebolehbinaan rekabentuk dan membangunkan satu senarai semakan
kebolehbinaan rekabentuk. Kajian ini dilaksanakan dengan melalui tiga fasa yang
utama, iaitu: fasa 1 melibatkan kajian literatur dan temuramah awalan; fasa 2
merangkumi temuramah berstruktur dengan pakar profesional dan pembangunan
model proses rekabentuk; fasa 3 terdiri daripada integrasi prinsip-prinsip
kebolehbinaan dan pembangunan senarai semakan kebolehbinaan rekabentuk. Data
flow diagram (DFD) dipakai dalam kajian ini untuk memodelkan aliran-aliran proses
rekabentuk itu. Akhirnya, hasil keputusan bagi kajian ini ialah pembangunan satu
model am bagi proses rekabentuk bangunan, model proses rekabentuk bangunan
yang telah diintegrasikan dan senarai semakan kebolehbinaan rekabentuk. Senarai
semakan ini bertindak sebagai satu alat untuk mempertingkatkan kebolehbinaan
suatu rekabentuk. Oleh sebab kesuntukan masa, hanya satu senarai semakan
kebolehbinaan rekabentuk dibangunkan dalam kajian ini.
vii
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
THESIS TITLE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xii
LIST OF FIGURES
xiii
LIST OF APPENDICES
xv
INTRODUCTION
1.1
Introduction
1
1.2
Problem Statement
2
1.3
The Objectives
3
1.4
Scope of Study
3
1.5
Research Methodology
4
LITERATURE REVIEW
2.1
Introduction
6
viii
2.2
Constructability Definitions
7
2.3
Development of the Principles of Constructability
8
2.4
An Overview of Project Life Cycle
17
2.5
Constructability Review in Design
23
2.5.1
The Guidelines
24
2.5.2
Computer Based System
24
2.5.3
Non-computer Based System
26
2.6
Responsibilities of Designers in Constructability
27
Enhancement
2.7
Constructability Principles for the Design Phase
29
2.7.1
Carry Out Thorough Investigation of the Site
30
2.7.2
Design for Minimum Time Below Ground
30
2.7.3
Design for Simple Assembly
32
2.7.4
Encourage Standardisation/Repetition
33
2.7.5
Design for Pre-fabrication, Pre-assembly or
34
Modularisation
2.7.6
Analyse Accessibility of the Jobsite
36
2.7.7
Employ Any Visualisation Tools Such As 3D
39
CAD to Avoid Physical Interference
2.7.8
Investigate Any Unsuspected Unrealistic or
40
Incompatible Tolerances
2.7.9
Investigate the Practical Sequence of
41
Construction
2.7.10 Plan to Avoid Damage to Work by
42
Subsequent Operations
2.7.11 Consider Storage Requirement at the Jobsite
44
2.7.12 Investigate the Impact of Design on Safety
44
During Construction
2.7.13 Design to Avoid Return Visit by Trade
46
2.7.14 Design for the Skills Available
47
2.7.15 Consider Suitability of Designed materials
47
2.7.16 Provide Detail and Clear Design Information
48
2.7.17 Design for Early Enclosure
49
2.7.18 Consider Adverse Weather Effect in Selecting
49
ix
Materials or Construction Method
2.8
3
Summary
50
RESEARCH METHODOLOGY
3.1
Introduction
53
3.2
Phase 1
55
3.2.1
Determine the Objectives and Scope
55
3.2.2
Literature Review
55
3.2.3
Preliminary Interview
56
3.3
3.4
Phase 2
57
3.3.1
The Interview
57
3.3.2
Develop Current Design Process Model
59
3.3.2.1 Data Flow Diagram (DFD)
59
3.3.2.2 Drawing A Data Flow Diagram
62
Phase 3
63
3.4.1
63
Integrating Constructability into Design
Process
3.5
4
3.4.2
Constructability Design Review Checklist
64
3.4.3
Review by Experts
65
Summary
65
DATA COLLECTION AND ANALYSIS
4.1
Introduction
67
4.2
The Architect Firm #1
67
4.2.1
Model of Architect Firm #A1
69
4.2.2
Additional Information from Architect
72
Firm #A1
4.3
The Consultancy Firm
74
4.3.1
The Consultancy Firm #C1
74
4.3.1.1 Model of Consultancy Firm #C1
76
x
4.3.1.2 Additional Information from
78
Consultancy Firm #C1
4.3.2
The Consultancy Firm #C2
79
4.3.2.1 Model of Consultancy Firm #C2
82
4.3.2.2 Additional Information from
85
Consultancy Firm #C2
4.3.3
The Consultancy Firm #C3
87
4.3.3.1 Model of Consultancy Firm #C3
89
4.3.3.2 Additional Information from
92
Consultancy Firm #C3
4.4
5
Summary
94
MODEL DEVELOPMENT AND DISCUSSION
5.1
Introduction
96
5.2
The General Building Design Process Model
96
5.3
The Constructability Integrated Building
105
Design Process Model
5.4
6
Summary
110
CHECKLIST DEVELOPMENT AND DISCUSSION
6.1
Introduction
112
6.2
The Development of Design Constructability
112
Checklist
7
6.3
The Discussion
114
6.4
Summary
114
CONCLUSIONS AND RECOMMENDATIONS
7.1
Introduction
116
xi
7.2
Conclusions
116
7.3
Recommendations for Future Research
118
REFERENCES
APPENDICES A – C
120
125 - 139
xii
LIST OF TABLES
TABLE NO.
TITLE
PAGE
3.1
Basic selection criteria in determining the interviewees
58
3.2
Components of a data flow diagram for design
60
4.1
The summary of the interviewee #A1 and #C1’s responses
94
4.2
The summary of the interviewee #C2 and #C3’s responses
95
5.1a
Inputs and outputs of process 1: preliminary design
102
5.1b
Inputs and outputs of process 1: preliminary design
103
(continue)
5.2a
Inputs and outputs of process 3: detailed design
103
5.2b
Inputs and outputs of process 3: detailed design (continue)
104
5.3
Inputs and outputs of process 2: estimating costs
104
5.4
Inputs and outputs of process 2: review design
110
constructability process
6.1
Item no. 1 of the building design constructability checklist
113
xiii
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Schematic of research methodology
5, 54
2.1
The life cycle of a construction project
18
2.2
Constructability cost-influence curve
23
2.3
Building on land reclaimed from sea
31
2.4
Steel-framed system build project: ground-floor plan
38
2.5
Steel beam on block walls
40
2.6
Revised scheme for practical sequence of construction
42
2.7
Typical floor beam with service holes
43
2.8
Two alternative designs for capping of a coal mineshaft
45
2.9
Elevation showing proposed development within an historic
46
terrace
3.1
Schematic of constructability integration into design process
64
4.1a
The current building design process model #A1: level 2,
70
preliminary design and detail design
4.1b
The current building design process model #A1: level 1
71
4.1c
The context diagram of current building design process
72
model #A1: level 0
4.2a
The current building design process model #C1: level 2,
77
preliminary design and detail design
4.2b
The current building design process model #C1: level 1
77
4.2c
The context diagram of current building design process
78
model #C1: level 0
4.3a
The current building design process model #C2: level 2,
preliminary design and detail design
83
xiv
4.3b
The current building design process model #C2: level 1
84
4.3c
The context diagram of current building design process
84
model #C2: level 0
4.4a
The current building design process model #C3: level 2,
90
preliminary design and detail design
4.4b
The current building design process model #C3: level 1
91
4.4c
The context diagram of current building design process
91
model #C3: level 0
5.1
The context diagram of general building design process
97
model: level 0
5.2
The general building design process model: level 1
98
5.3
The general building design process model: level 2,
99
preliminary design
5.4
The general building design process model: level 2,
101
detailed design
5.5
The context diagram of constructability integrated building
105
design process model: level 0
5.6
The constructability integrated building design process
106
model: level 2, preliminary design
5.7
The constructability integrated building design process
107
model: level 2, detailed design
5.8
The constructability integrated building design process
model: level 1
109
xv
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
The Interview Questionnaire Form
125
B
Building Design Constructability Checklist –
130
Assesment on Foundation
C
Design Phase’s Constructability Principles That Being
Inserted
136
1
CHAPTER 1
INTRODUCTION
1.1
Introduction
In the late of 1970s, the constructability concept emerged and evolved from
studies into how improvement can be achieved to increase cost efficiency and quality
in the construction industry. Nowadays, constructability concept has been
extensively being developed and applied in the USA, UK and later in Australia,
where their studies have demonstrated that improved constructability has lead to
significant savings in both cost and time required for completing construction
projects (Russel et al., 1992a; Jergeas and Van der Put, 2001).
However, according to Nima et al. (2001), in Malaysia there are neither
reliable documentation nor available sources that detail those constructability
concepts and guide their application. Therefore, for those who has site experience
certainly has heard the words “how is this going to fit” or “how am I suppose to build
this thing”. Such of these on site frustration can often be traced back to design
decisions that lacked of knowledge regarding on how the object would be built. It
seems that the design process should include constructability input and critiques.
However, there still a little or surprisingly no explicit constructability input is
provided to the design phase that always leads to frustration mentioned above, slower
and more costly construction period and changes. Hence, Malaysian engineers have a
disadvantage by not knowing what, when and how they shall enhance the project
2
constructability in design stage, when compared with the engineers in more
developed countries.
1.2
Problem Statement
In the construction process of a traditional contracting system, it is the A/E’s
responsibility to develop a design that able to produce a project that, when it is
implemented by the contractor, meets the client’s needs and expectation. However,
by the A/E’s very nature, A/Es are not exactly expert in construction means and
methods. According to Glavinich (1995), most design drawings and specifications
that produced by the design engineers are tend to be performance oriented,
specifying an end result and materials, while leaves the means and methods for
constructing the work to the contractor. As a result, the reality of construction is that
most of the problems encountered in the field are often compounded by inherent
design flaws that generated in the design phase. Therefore, it is important to
emphasis constructability during the early stage of a design. Besides, many studies
(Paulson, 1976; Glavinich, 1995; Mendelsohn, 1997; Nima et al., 1999; Nima et al.,
2004) found that integrating constructability knowledge into design processes is the
best time to influence project costs, decrease the likelihood of delays, contract
change orders due to unforeseen site conditions and legal entanglement and claims.
In Malaysia, a study about the implementation of constructability in the
Malaysian construction industry has been carried out by Nima et al. (2001). In this
study, it was found that there is an acceptance of the majority constructability
concepts by the Malaysian engineers from the theoretical point of view. However,
they generally did not apply these concepts in their practices, especially during the
design phase. One of the reasons is due to current design practice which does not
incorporate constructability as part of the design process. Therefore, it is needed to
predetermine the current local design process of a building design, before proposing
any further design process improvement that integrates constructability concepts.
3
Constructability concept can be implemented in design on several ways.
Several researchers have developed develop tools that can be use and to enhance the
constructability of project designs (Anderson et al., 2000; Arditi et al., 2002; Navon
et al., 2000; Soibelman et al., 2003; Pulaski and Horman, 2005). However, the level
of formality of those methods is varied. It is because some of them are very formal as
they incorporated the constructability concepts, such as specifying constructability
objectives, forming a constructability team and identifying means to obtain
constructability input. While, several methods incorporate constructability only
through standard design procedures. Nonetheless, constructability improvement tool
in the form of checklist is considered to be comprehensive in term of the concepts
covered (Rosli, 2004). Suitable constructability checklist for the local construction
industry is currently unavailable, therefore, as initially, it is essential to develop a
constructability checklist that able to check a design work.
1.3
The Objectives
The following are the objectives of this study:
a)
To determine the local construction industry’s current building design
process.
b)
To propose a model that integrates constructability to the general
building design process.
c)
1.4
To develop a building design constructability checklist.
Scope of Study
In this study, three case studies of building projects that are carried under the
local traditional contracting system, where its design stage is significantly separated
from the construction stage, will be the type of project investigated.
4
Although the constructability concepts can be implemented through the entire
project life cycle: i.e. from conceptual planning until construction, however, the
study will only focus on the constructability improvement at the design phase.
In order to develop the building design constructability checklist, the design
phase’s constructability principles identified by Rosli (2004) will be used. Therefore,
those principles will not be formulated by the writer in this study. Besides, due to
limitation of time, only a sample of building design constructability checklist for
foundation assessment I developed fore reviewing and checking the design work.
1.5
Research Methodology
Research methodology is a framework for the researcher on how a study is
carried out, such as process of collecting, analyzing, interpreting observations.
Therefore, Figure 1.1 outlined the research methodology of this study. It is divided
into three phases: Phase 1 encompasses literature review and preliminary interview
with experts in local construction industry; Phase 2 involves the case studies of
current designs process and its constructability issue. After that, a current design
process model is developed based on the case studies and lastly, Phase 3 consists of
design process improvement by integrating constructability concepts and
development of a design review checklist based on a selected work.
5
Determine Objective
and Scope
Phase 1
Preliminary Interview
Literature Review
Case Studies
-
Investigate local current design process
-
Constructability issue
Phase 2
Develop Current Design
Process Model
Integrating Constructability
into Design Process
Develop Building Design
Constructability Checklist
No
Review by Experts
Yes
Conclusion / Recommendation
Figure 1.1 : Schematic of research methodology
Phase 3
6
CHAPTER 2
LITERATURE REVIEW
2.1
Introduction
Implementation of constructability in construction projects can boost an
important bearing on the success of the project. Many of the design decisions and
solutions made early in the project’s design process affect the construction of the
project. Consequently, construction expertise is often required to be incorporated in
the design process to improve the constructability of the design.
Within last three decade ago, many researchers have utilized the construction
knowledge and experience as the constructability input to improve the
constructability throughout construction project life cycle. Hence, this chapter
reviews some of the constructability definitions and development of constructability
principles throughout the project life cycle. Besides, phases involve in the project life
cycle are briefly discussed, particularly the design phase, in order to highlight the
benefits of implementation of constructability in term of cost.
Totally, there are eighteen constructability principles for design phase that
derived by Rosli (2004) are discussed. These principles will be used for
constructability integration into the current design process and development of a
building design constructability checklist, which will be covered in following
chapters.
7
2.2
Constructability Definitions
Within these several decades, many researchers have defined the
constructability term in their studies in a number of ways. However, all of these
definitions stress the importance of overall project objectives. Below are some of the
constructability definitions that referred from their studies:
•
In the United Kingdom , the Construction Industry Research and
Information Association (CIRIA) was tentatively defined the buildability
(constructability) as (CIRIA, 1983):
… the extent to which the design of a building facilitates ease
of construction, subject to the overall requirements for the
completed building.
•
In the United States the constructability term as defined by the
Construction Industry Institute (CII, 1986), is the optimum use if
construction knowledge and experience in the conceptual planning,
engineering, procurement, and field operation phases to achieve the
overall project objectives.
•
Constructability is the optimum integration of construction knowledge
and experience in planning, engineering, procurement, and field
operations to achieve overall project objectives (O’Connor et al., 1987).
•
Constructability is the ability to construct a building efficiently,
economically and tend to agreed quality levels from its constituent
materials, components and sub-assemblies (Ferguson, 1989).
•
Constructability is a measure of the ease or expediency with which a
facility can be constructed ( Hugo et al., 1990)
8
•
Constructability is often portrayed as integrating construction knowledge,
resources, technology and experience into the engineering and design of a
project (Anderson et al., 1995).
•
Fisher and Tatum (1997) were looking for a working definition that
directly addressed the design-construction interface. Therefore, they
modified the U.K. definition as:
Constructability is the extent to which the design of the
building facilitates ease of construction, subject to the
requirements of construction method
(Fisher and Tatum, 1997).
•
Constructability is the integration of construction expertise into the
planning and design of a project so that the construction forces have the
maximum opportunity to deliver the project in conformity with cost,
quality, schedule and safety objectives of the project’s stakeholders
(Mendelsohn, 1997).
2.3
Development of the Principles of Constructability
In the last two decade, the construction industry suffered from lack of
constructability implementation. This is due to the construction designs were not
providing value for money in term of efficiency with which the construction was
being executed. Consequently, it has caused many problems such as increased cost
and time required for constructing a project, reduced productivity of project
personnel and equipment and low quality construction (Nima et al., 2004). Therefore,
researchers in United Kingdom, United States and Australia realized the seriousness
of this inherent shortcomings and limitation of the traditional owner-designercontractor interaction. Hence, they had conducted numbers of studies regarding to
9
the constructability and suggested the solution to resolve it during the conceptual
planning, design, procurement or field operation stages.
In the 1970s, research on constructability concepts was conducted in the UK
by the CIRIA. The primary aim of the research was to identify those factors in the
design of a construction project that have an impact on site construction techniques
(Griffith, 1984). From that research, the CIRIA identified seven categories of
“Buildability Guidelines” in year 1983, which are:
•
Carry out thorough investigation and design.
•
Plan for essential site production requirements.
•
Plan for a practical sequence of operations and early enclosure.
•
Plan for simplicity of assembly and logical trade sequence.
•
Detail for maximum repetition and standardisation.
•
Detail for achievable tolerances.
•
Specify robust ad suitable material.
As the conclusion of the report, the CIRIA highlighted that three construction
parties: the owners, designers and contractors will be benefited form major cost by
implementing good constructability, and its achievement depends upon on both
designers’ and contractors’ ability to figure out the whole construction process
through each others’ eyes.
Later, the CIRIA commissioned further research to above tentative
“Buildability Principles” and those seven principles were expanded into sixteen more
definite “design principles” for practical buildability, that presented by Adam (1989).
Some practical examples are used to define and describe each design principle, and
all of those practical design examples have been documented. Meanwhile, the sixteen
design principles may be briefly state as below:
•
Investigate thoroughly.
•
Consider access at the design stage.
10
•
Consider storage at the design stage.
•
Design for minimum time below ground.
•
Design for early enclosure.
•
Use suitable materials.
•
Design for skills available.
•
Design for simple assembly.
•
Plan for maximum repetition and/or standardisation.
•
Maximize the use of plant.
•
Allow for sensible tolerances.
•
Allow for a practical sequence of operations.
•
Avoid return visit by trades.
•
Plan to avoid change to work by subsequent operations.
•
Design for safe construction.
•
Communicate clearly.
While, in the US, the Construction Industry Institutes (CII) was established in
1983 with a mission to improve the cost effectiveness, total quality management and
international competitiveness of the construction industry. Therefore, the
constructability has been a major aim of the CII, where during those periods, parallel
with the UK but unrelated studies had been undertaken by several scholars in the
United States. Based on the research of Tatum (1987), three principles that could
improve constructability during conceptual planning stage have been identified,
resulted form fifteen case studies in commercial, industrial and public infrastructure
building. They are:
•
Development of the project plan.
•
Laying out of the site.
•
Selection of major construction methods.
Besides, the effectiveness of utilization constructability knowledge during the
engineering and procurement stage of a project had been examined by O’Connor et
al. (1987). In this study, they had conducted some interviews with the project
11
personnel from different organizations. And, information which constructability
concept could be derived was acquired by utilizing numbers of data collection
method. At a result, it derived seven constructability principles, where
constructability during the engineering and procurement phase is enhanced when:
•
Design and procurement schedules are construction-driven.
•
Designs are configured to enable efficient construction.
•
Design elements are standardized and repetition is taken advantage of.
•
Pre-assembly work is scoped o advance and module and/or pre-assembly
design are prepared to facilitate fabrication, transport and installation.
•
Designs promote the accessibility of manpower, material and equipment.
•
Designs facilitate construction under adverse weather conditions when
they exist.
•
Specifications are viewed in detail by owner, designer and construction
personnel and serve to simplify the field construction process.
Furthermore, O’Connor and Davis (1988) also had identified a single prime
constructability concept for the construction improvement during the field operations.
In the research, from the data that they had obtained through site interviews on
fourteen projects, they concluded that:
Constructability is enhanced when innovative construction methods
are utilized
(O’Connor and Davis, 1988).
Besides, the study also identified and further discussed seven innovative construction
methods that may involve, which is highlighted as below:
•
Innovative definitive sequencing of field tasks.
•
Innovative uses of temporary construction materials/system.
•
Innovative uses of hand tool.
•
Innovative uses of construction equipment.
12
•
Constructor-optional pre-assembly.
•
Innovative temporary facilities directly supportive of field methods.
•
Post-bid constructor preferences related to the layout, design and
selection of permanent materials.
Consequently, the CII in Texas integrated and documented the three studies
into the constructability concepts file. Therefore, within in the concepts file, six
constructability principles defined for the conceptual planning stage, seven principles
for the design and procurement stage and one principle during the field operations
stage, which are detailed the whole project life cycle constructability improvement
principles. Later, in 1992, CII added three new constructability principles on the
previous fourteen principles. Two new principles for constructability improvement
during conceptual planning are:
•
Project teams responsible for constructability are identified early on.
•
Advanced information technologies are applied throughout project.
And, a new constructability principle for the design and procurement stage is:
•
Design and construction sequencing should facilitate system turn-over
and start up.
Meanwhile, the Australian CII (CIIA), which it collaborated with the CII in
the United State, developed a constructability principles file that suitable for the their
context (CIIA, 1993). Twelve principles have been developed and it encourages the
project team to apply them where appropriate. Those principles are:
•
Constructability must be made an integral part of the project plan.
•
Project planning must actively involve construction knowledge and
experience.
13
•
The experience, skills and composition o the project team must be
appropriate for the project.
•
Constructability is enhance when the project team gains an understanding
of the client’s corporate and project objectives.
•
The technology pf the design solution must be matched with the skills and
resources available.
•
External factors can affect the cost and/or program of the project.
•
The overall programme for the project must be realistic and construction
sensitive, and have the commitment of the project team.
•
The project design must consider construction methodology.
•
Consider construction accessibility in the design and construction stages
of the project.
•
Consider construction efficiency in specification development.
•
Utilization of innovative technique during construction stage.
•
Constructability can be enhanced on similar suture projects if a postconstruction analysis is undertaken by the project team.
In Malaysia, a pioneer of constructability study in this country has been
conducted by Nima (2001). Based on those the above literatures, Nima (2001) had
formulated
twenty-three
constructability
concepts
that
able
to
contribute
improvement to the construction project process, which starting form conceptual
planning until the end of the project start-up and construction. Significantly, the
constructability concepts for design and procurement phases are also combined as a
one stage, which it is similar as the CII. It is because the development of these
concepts by Nima (2001) is referred to the CII’s constructability principles
mentioned above.
According to project stages, the enhancements of project constructability
concepts are summarized as follows:
14
•
During the conceptual planning phase comprises of Concepts C1 – C7:
a) Concept C1: Discuss and document the project constructability
program within the project execution plan, thorough the participation
of all project team members.
b) Concept C2: A project team that includes representatives of the owner,
engineer and contractor should be formulated and maintained to take
the constructability issue into consideration from the outset of the
project and through all of its phases.
c) Concept C3: Individuals with current construction knowledge and
experience should achieve the early project planning so that
interference between design and construction can be avoided.
d) Concept C4: The construction methods should be taken into
consideration when choosing the type and the number of contracts
required for executing the project.
e) Concept C5: The master project schedule and the construction
completion date should be construction-sensitive and should be
assigned as early as possible.
f) Concept C6: In order to accomplish the field operations easily and
efficiently, major construction methods should be discussed and
analyzed in-depth as early as possible to direct the design according to
these methods.
g) Concept C7: Site layout should be studied carefully so that
construction, operation and maintenance can be performed efficiently,
and to avoid interference between the activities performed during
these phases.
15
•
During the design and procurement phases comprises of Concepts C8 –
C15:
a) Concept C8: Design and procurement schedules should be dictated by
construction sequence. Thus, the construction schedule must be
discussed and developed prior to the design development and
procurement schedule.
b) Concept C9: Advanced information technologies are important to any
field including the construction industry. Therefore, the use of those
technologies will overcome the problem of fragmentation into
specialized roles in this field, and enhance constructability.
c) Concept C10: Designs, through design simplification by designers and
design review by qualified construction personnel, must be configured
to enable efficient construction.
d) Concept C11: Project elements should be standardized to an extent
that will never affect the project cost negatively.
e) Concept C12: The project technical specifications should be
simplified and configured to achieve efficient construction without
sacrificing the level or the efficiency of the project performance.
f) Concept C13: The implementation of modularization and preassembly
for project elements should be taken into consideration and studied
carefully. Modularization and preassembly design should be prepared
to facilitate fabrication, transportation and installation.
g) Concept C14: Project design should take into consideration the
accessibility of construction personnel, materials and equipment to the
required position inside the site.
h) Concept C15: Design should facilitate construction during adverse
weather conditions. Efforts should be made to plan for the
construction of the project under suitable weather conditions;
16
otherwise, the designer must increase the project elements that could
be prefabricated in workshops.
•
During the field operations phase comprises of Concepts C16 – C23:
a) Concept C16: Field tasks sequencing should be configured in order to
minimize damages or rework of some project elements, minimize
scaffolding needs, formwork used, or congestion of construction
personnel, material and equipment.
b) Concept C17: Innovation in temporary construction materials/systems,
or implementing innovative ways of using available temporary
construction materials/systems that have not been defined or limited
by the design drawings and technical specifications.
c) Concept C18: Incorporating innovation of new methods in using offthe-shelf hand tools, or modification of the available tools, or
introduction of a new hand tools that reduce labour intensity, increase
mobility, safety or accessibility.
d) Concept C19: Introduction of innovative methods for using the
available equipment or modification of the available equipment to
increase their productivity.
e) Concept C20: Encourage the constructor to use any optional
preassembly, reduce the need for scaffolding, or improve the project
constructability under adverse weather conditions, in order to increase
the productivity.
f) Concept C21: Encourage the constructor to carry out innovation of
temporary facilities.
g) Concept C22: Good contractors, based on quality and time, should be
documented, so that contracts for future construction works would not
be awarded based on low bids only, but by considering other project
attributes, i.e. quality and time.
17
h) Concept C23: Evaluation, documentation and feedback of the issues
of the constructability concepts should be maintained throughout the
project to be used in later projects as lessons learned.
Instead of the Nima’s (2001) constructability concepts, Rosli (2004) also has
identified eighteen constructability principles for improvement of the design phase
by collaborating of those principles found from those researchers. By the way,
“constructability concepts” and “constructability principles” mean a similar thing,
where O’Connor et al. (1987) defined it as significant, distinct, and executable
objectives for enhancing constructability. Principles or concepts are not specific or
unique with respect to project type or organization. They are abstract from the
analysis idea.
These eighteen constructability principles, which used during the project
design phase, are more thorough with respect to ease of construction. Hence, this
design phase’s constructability principles are used in this case study for proposing
the improvement to existing design process and development of a constructability
design review checklist, which they are further discussed in section 2.7.
2.4
An Overview of Project Life Cycle
From concept to implementation, stages in the development of building
construction project fall into broadly consistent pattern, but the differences is in
timing and degree of emphasis each project takes on its own unique character. While
in traditional building delivery system, the stages are normally occurred in
sequentially. The life cycle of a design/bid/build project comprises of six basic
phases, which contribute to developing project from an idea to reality. The phases are
concept and feasibility studies, design, procurement, construction or also known as
field operations, start-up and implementation, and operation or utilisation, which
shown as in Figure 2.1
18
Figure 2.1
The life cycle of a construction project (Adapted from Barrie and
Paulson, 1984)
First of all, the conceptual planning and feasibility studies phase of a
construction project is the recognition of a need for a new facility. Elements of this
phase include conceptual analysis, determination of project’s objectives scope and
time, technical and economic feasibility studies, traffic impact assessment, and
environmental impact reports. Traditionally, this early stage is handled by the owner
alone, or by the owner working with consultants knowledgeable of the most
important affecting situation. Previously, constructability is not thought of at all at
this conceptual stage, but nowadays, due to the competitive and complexity of the
project, modern construction demands that constructability is urged to be considered
at this early stage. Therefore, to some extent, architect or engineer consultants,
design-constructor, or professional construction managers may be involved in this
early phase. For example, the owner may request architects to provide early design
advice, and construction professionals offer cost and constructability advice. Then,
their advice helps an owner make a more informed decision about feasibility of a
specific project (Gould and Joyce, 2000).
After the concept and feasibility studies, the project will be bring forward to
the design phase once the owner has decided to proceed. According to Barrie and
Paulson (1984), the design phase consists of two main phases, which are preliminary
engineering and design, and detailed engineering and design. Basically in the
19
building project, these phases are domain by architects and design-oriented engineers.
However, in order to promote the consideration of constructability in this design
phase, the owner’s operation and utilisation knowledge and the field constructor’s
experience are need to be more strongly injected at this stage through both direct
participation and stringent the design review procedures. Because of this study is
focused on the improvement of design process by integrating constructability,
therefore it is essential to further review those two phases’ activities involve in this
design stage.
a) Preliminary Design
Preliminary design stresses the development of architectural concepts,
evaluation of technological process alternatives, the project size and
capacity decisions, and comparative economic studies. To a great extent,
these steps evolve directly from the conceptual and feasibility stage, and
therefore it is sometimes difficult to see where one leaves off and the
other begins (Barrie and Paulson, 1984). Generally, the aim of
preliminary design is to define the design criteria, gather all the necessary
information, and create a first pass solution which comes as close as
possible to fulfilling the requirements laid out in the design process.
Hence, the owner may do the site investigation so that he/she can give the
designer information about soil conditions and for determination the type
of foundation and structure possible for that particular site. Besides, the
architect develops preliminary floor plans to reflect the relationships of
the various functional areas to one another, and sitting and location of the
building, which they are determined as well as its visual form. Thus, the
architect has the primary responsibility for preliminary design in building
construction.
An example illustrated by Barrie and Paulson (1984) that in a high
rise building project the preliminary design determines the number and
spacing of the stories, the general layout of the service an occupied floor
spaces, general functional allocations, as like office space, parking, retail
and etc, and the overall design approach. Several design alternatives will
20
need to be decided in this stage too, such as the choice between bolted
structural-steel frame or a reinforced-concrete structure. Further
refinements determine whether the structure will be cast in-situ concrete
or precast. Hence, any decision take by the designers in this stage, give
significant influence and impact to the project constructability, cost and
its following project life cycle phases.
Once this preliminary engineering and design are complete, there is
generally an extensive review process before the commencement of
detailed work.
b) Detailed Design
Detailed design involve the process of successively breaking down,
analyzing, and designing the structure and its elements so that it complies
with recognized standards of safety and performance while rendering the
design in the form of a set of explicit drawings and specifications that will
tell the constructors exactly how to build the structure in the field (Barrie
and Paulson, 1984).
During this detailed phase, the architects, interior designers, landscape
architects, the professional construction consultant, and other engineering
disciplines such as chemical, electrical, mechanical and other engineers,
finalize the design of the major building system and structure. In addition
to designing the structure itself, the design professional often conduct
some detailed field studies to get better engineering information on
foundation conditions, slope stability, and structural properties of natural
materials, where it also require further input from experts in other
disciplines, likes geologists, economists, and environment scientist.
Besides, the success of a building project is highly correlated with the
quality and depth of the plans prepared during this phase. A detailed
design review of each plan and drawing, and each aspect of the project is
21
therefore conducted prior to approval. In addition, construction cost
estimates are refigured with the availability of sufficient information so
that to generate the final cost of the project, which concerned most by the
owner. Again, it is essential for field construction method and cost
knowledge to be injected into the detailed engineering and design process,
in order to enhance the constructability of the design to ease of
construction.
After the project designs are completed, the project will be ready for
tendering process in procurement phase. According to Gould and Joyce (2000),
procurement is defined as the overall process of finding and purchasing the materials
called for in the contract and hiring the best subcontractor to build the project. From
that definition, procurement stage involves two main activities. One is contracting
and subcontracting for services of general and specialty contractors. While the other
is obtaining materials and equipment required to construct the project. In the
traditional project delivery system, procuring process takes place soon after the
detailed engineering and design phase has produced a comprehensive set of plans
and specifications. If the constructability has been considered adequately throughout
the foregoing stages, then now it is a case of detailing the requirements for
constructability within the project tender. The requirements for constructability
should forms an integral aspect of the tendering process, and prospective contractors
are allow for considerations of constructability in their submitted tenders and assume
the responsibility for the implementation aspects during the construction itself.
Subsequently, construction is the process whereby designer’s plan and
specification are converted into physical structures and facilities. It involves the
organization and coordination of all the resources for the project by the constructors.
In the traditional form of contract, the main contractor handles all subcontracting
works. Therefore, the contractor should ensure that the general constructability
principles are also carried out by the subcontractors and other providers of specialist
input to the process. Besides, there is also considerable input for work inspections
and interpretation from the architect and engineer. Hence, contractor needs to liaise
22
and work with the design team, and to provide constructability feedback on the
construction phase for future analysis.
After the construction phase, the next stage is start-up and implementation.
Most structures and facilities of any significance involve a start-up and
implementation phase, where the testing of components is done while the project is
underway. The start-up and implementation is important because it needs to ensure
that all components installed are function well as a total system. Due to all the works
have been executed, building accessories have been installed and project nears to
completion, any changes of works in this stage for achieving the constructability will
be very difficult and costly. While in operation and utilisation phase, the building
project is whole completed and hand over to the owner and/or tenant of the building
for operation and utilisation, and usually this stage does not involve the designer
teams. Therefore, it is impossible to promote constructability in this the end of the
project life cycle.
As a conclusion, each phase throughout the project life cycle involves
different kind of activities and they require different degree of involvement from the
owner, consultants, professional constructors, and expertises from other disciplines,
to contribute their efforts for the success of the project. According to Mendelsohn
(1997), the reality of construction is that probably 75% of the problems encountered
in the field are generated in the design phase. In addition, Fischer and Tatum (1997)
claimed that the designers play an important role in achieving superior
constructability. Therefore, it is better for the designers to consider the
constructability of the construction project during the early phase, particularly during
the design phase, so that it able to contribute significant influence to the project cost,
which illustrated in Figure 2.2. Thus, the following section will discuss the
constructability principles for the design phase, which the designers can employ it to
improve the project constructability during the design stage.
23
Figure 2.2 : Constructability cost-influence curve (Adapted from CII, 1986)
2.5
Constructability Review in Design
Numbers of research organizations (CII, CIRIA, and CIIA) and independent
studies (Ireland, 1985; ASCE 1991; Russell et al., 1993) confirmed that integrating
construction knowledge onto design process greatly improves the chances of
achieving a better quality project, completed a safer manner, on schedule, for the
least cost (Arditi, 2002). As a result, numerous constructability review and
improvement methods have been developed for the construction industry. Among
those methods used for constructability reviews in design phase are categorized as
the guidelines, computer based system, and non-computer based system.
24
2.5.1
The Guidelines
Guidelines are one of the most general constructability review methods can
be found in construction industry. Such guidelines that commonly being used for
constructability reviews in design phase are based on the constructability principles
developed by CIRIA, CII and CIIA, which they had been mentioned in section 2.3.
Generally, the guidelines provided by those research organizations are aimed at
providing designers with further details of main constructability principles that need
to be considered during the design process (Rosli, 2004). ). Despite of the
constructability guidelines are comprehensive in term of coverage, however, the
applications of these constructability principles are too general and may difficult to
apply in a building project’s design phase. Therefore, it is difficult to provide
significant mean to evaluate constructability improvement of project design and
make the designers difficult to judge whether the project design has met the desired
level of constructability.
2.5.2
Computer Based System
The computer based system enables constructability to be applied easily by
designers particularly for those who are limited in constructability knowledge.
Among the computer based system that deal with the organization and utilization of
constructability knowledge for design are the design relevant constructability
knowledge and Conceptual Product/Process Matrix Model (CPPMM) that introduced
by Fisher and Tatum (1997) and Pulaski and Horman (2005) respectively.
The design relevant constructability knowledge is an expert system that
enables the designers to make use of constructability knowledge at the right time
during design development, in order to improve their design constructability. In this
system, Fisher and Tatum (1997) classified the knowledge by construction methods
and structure elements to ensure appropriate and specific constructability input.
Besides, they also divided the constructability knowledge into five groups, there are:
25
application heuristics, layout knowledge, dimensioning knowledge, detailing
knowledge, and exogenous knowledge.
The Conceptual Product/Process Matrix Model (CPPMM) introduced by
Pulaski and Horman (2005) is more advanced than the design relevant
constructability knowledge system. It is because CPPMM’s purpose is not only to
organize constructability information for design that allow the right information to be
made available to the designers, besides, it also allow the right information is
available to designers at an appropriate level of detail and at the proper phase of
design. This model consists of two existing models: Product model Architecture
(PMA) and Integrated Building Process Model (IBPM). In addition, they also
introduced the constructability metric which it is a method to measure how effective
of the design teams are at addressing constructability issues in timely manner. The
advantage of the CPPMM is that it links constructability rules to different stages of
building design in a step-by-step format. Besides, this model can be used to expose
specific information requirements necessary to progress design, and thus be used to
improve the quality of information flow across the design stage.
On the other hand, Navon et al. (2000) also have developed an automated
rebar constructability diagnosis which this computerised system model is intended to
be used during the rebar detailing stage within the design phase. This model consists
of two modules: diagnosis module and correction module. The diagnosis module is
used to automatically diagnose potential rebar-related constructability problems, such
as high congestion of reinforcement bars, collision between bars, and collision
between bars and building system. Then, constructability report will be generated
with regarding to those three constructability checking and reports them to the
designer. For the correction module, it functions as offering solutions to the detected
problems and implementing them. However, only the prototype of the diagnosis
module has been developed and it was limited to dealing with rectangular beams.
The main advantages of this system are reduction of time in constructability review,
a true 3D diagnosis tool that enable designers to visualize to those three
constructability problems and even inexperience designers can produce much better
beam designs. Nevertheless, this computer based model does not considered other
26
design phase’s constructability principles, where it just evaluate the principles of
designing for simple assembly and employing visualization tool to avoid physical
interferences.
2.5.3
Non-computer Based System
The non-computer based system is a manual method for constructability
improvement by using formula and scale in theirs system. Among this method that
are buildable design appraisal system (BDAS, 200) developed by Construction
Industry Development Board of Singapore and “hierarchy of difficulty” of assembly
studied by Ferguson (1989).
Singapore is a small island country and limited of land, hence the Singapore
local authority has mandatory all the submission of designs should include the
assessment of constructability prior to the approval of the designs. So, they have
introduced the buildable design appraisal system, which its objectives is to promote
more constructable designs to the industry through assessing contribution to site
efficiency and productivity. While, the constructability principles that considered by
this system are design for simple assembly, encourage standardization, and design
for pre-assembly and/or modularization. In this system, points are awarded based on
the types of structural system and architectural system, such as internal and external
walls, windows and doors components. More points will be awarded to more
constructable system, where the maximum point that can be achieve is 100.
Besides, Ferguson (1989) has introduced the “hierarchy of difficulty” of
assembly for the element and building components. He defined the hierarchy into
five scales, which are assembly impossible, assembly only possible with extremely
difficulty, assembly possible but difficult, assembly straightforward but perverse, and
assembly easy. Generally, it provides an approach to designers for identifying the
degree of ease of assembly for any components or sub-assemblies from the designs.
Obviously, this “hierarchy of difficultly” approach only considered the “design for
27
simple assembly” principle in order to ease of construction. However, there are still
inadequate to promote a throughout constructability enhancement of a project design,
where other aspect of constructability could not be assessed by this system.
2.6
Responsibilities of Designers in Constructability Enhancement
Architects and engineers are the principle designers of construction projects.
On most building and residential sector projects, the architect is the lead designer,
laying out the concept on paper with the owner (Gould, 2000). On the other hand, the
engineer is usually brought in after the basic concept is worked out but before the
details are developed. Generally, the designers are responsible for producing design
alternatives, design computations, drawings, and specification that meet the needs of
the owner. In addition, it is the duty of the designers to produce a project design that
meets all federal, state, and local codes, such as design standards; environmental and
safety regulations (Oberlender, 2000).
Despite of their primary function is to design, but this also includes the
undertaking of necessary research work, the calculation of estimated costs, and the
appraisal of the estimated output of the works and their economic value for the
owner. They must know and be able to give assurances that the work that they
propose is practicable, constructable, and fulfilling its intended functions as well as
its cost. Hence, Nima et al. (1999) cited that the designers’ personnel play a
prominent role in enhancing the constructability of facilities design, construction and
assessment. And yet, the designers have the following responsibilities to enhance
constructability in a building project (Nima et al., 1999):
•
Encourage the owner to implement a constructability program through the
project execution plan and let the owner understand the important and
benefits of constructability program. Moreover, the designers can make
use of the available documentation on constructability programs.
28
•
The designers should be restricted to the startup and construction
sequence when establishing procurement and engineering sequences, and
the master project schedule
•
In order to prepare a proper facility design, the designers should analyze
the major construction methods in-depth as early as possible.
•
In order to enhance constructability, the designers should keep an eye on
the concept site layouts by taking the project site layout into consideration
when they prepare project designs.
•
Designers should exploit the capabilities and benefits of advanced
information technology, such as online engineering database computer
support mechanism.
•
Designers should simplify the designs, and should configure them in
simple and clear drawings in which the design enables efficient
construction.
•
Standardizing the design elements as much as possible where the
designers
should
analyze
designs
and
identify
elements
with
standardisation potential.
•
The designers should give extra effort for tailoring of technical
specifications to achieve efficient construction.
•
Increasing the use of the module/preassembly designs to facilitate
fabrication, transportation and installation.
•
Preparing designs that has been considered and promote accessibility of
manpower, material and equipment.
29
•
Preparing designs that facilitate construction under adverse weather
conditions.
In order to promote and enhance the implementation of constructability
during the design phase, following section discussed the constructability principles
that can be adopted to assist the designers to carry out their responsibilities as
mentioned above.
2.7
Constructability Principles for the Design Phase
Griffith and Sidwell (1995) defined design constructability as the detailed
consideration of design elements to meet the technical and financial requirements of
the project, with consideration, where feasible, to the design-construction
relationship in order to improve design effectiveness and in so doing assist the
construction process on site.
However, the constructability principles for design phases that identified by
Rosli (2004) are more thorough with respect to ease of construction. These principles
are more focused and specified for the constructability improvement of design phase
rather than those principles developed by CII and CIRIA, which the applications are
too general and difficult to apply in a building project’s design phase.
Therefore, in this section, total of eighteen design phase’s constructability
principles that derived by Rosli (2004) are discussed in detail. Those concepts are:
30
2.7.1
Carry Out Thorough Investigation of the Site
Constructability can be enhanced if the information gathered form site
investigation is thorough, complete and presented clearly before the construction
commencement. According to the context of CIRIA in Buildability : An Assessment
(1983), among the information that need to be gathered are the site conditions,
underground hazards and other circumstances that are likely to affect the course of
the project and construction, in order to avoid the risk of subsequent expensive delay
and alteration after the construction has commenced.
For example in the work of drilled shaft construction that highlighted by
Turner (1992), which the site investigation has the greatest potential to influence the
cost of drilled shafts. It is because the drilled shaft construction, performance and
cost are sensitive to some of the ground conditions that may not be determined
adequately by a conventional boring program. Therefore, a more thorough and
careful site characterization is required for the drilled shafts than for other foundation
systems, such as determination of reliable soil and rock properties for the design and
description of “geological detail that influence drilled shafts construction and
performance.
2.7.2
Design for Minimum Time Below Ground
Project constructability enhancement can be achieved if the design includes
the consideration of the minimum work below ground level. During the design stage,
this principle is important particularly for projects that need to be carried on the
ground where it is hazardous, poor and wet. It is because design for minimum time
below ground level able to influence and facilitate the speed and flow of the project,
and as a result, it minimise the amount of time required by work below the ground
and improve the construction productivity. However, the design engineer shall
identify the conditions likely to be met with below ground level and not creating
problems for the contractor in term of the required amount of work below ground.
31
An example mentioned by Adam (1989), that a site was on a coastal plain,
with hills behind providing a low cost source of limestone as shown in Figure 2.3a,
which all substantial buildings of the flat area had been piled. Because of that,
normal falls on drains were difficult to achieve due to the flatness of the land.
Besides, the ground water table observed in October was high (Figure 2.3b) and it
would be anticipated high throughout of the year. In spite of using raft foundation
with likely to be had high settlement, a mat of stone was designed and built (Figure
2.3c), which it allowed almost all working to be done in the dry at a time of year and
avoided the troublesome of work below ground. Compared with the raft foundation
that has very low bearing stress, the mat of stone able to give a dispersion of load on
to the subsoil, and then it allowed higher bearing pressure to be used immediately
below the raft, shown in Figure 2.3d. In addition, the extra height achieved in this
way also allowed the maximum available fall to be provided to the drains. The
another advantage of this technique is the general contractor has the control by
avoiding the need for a specialist piling subcontractor, where extra time will be
needed in this construction.
Figure 2.3(a, b, c, d)
Adams, 1989)
Building on land reclaimed from sea (Adapted from
32
2.7.3
Design for Simple Assembly
Simplicity is a desirable element of any constructable design, where it shall
be progressive rather than reactionary. It is also refers to the use of uncomplicated
building construction system and installation details, such as the flat plate system that
can eases formwork construction as well as reinforcement considerably (Building
and Construction Authority, 2000). In addition, by referring to Adam (1989), the
designer should attempt to produce the details as simple as possible which
compatible with the overall requirements for the building, particular element, or a
group of elements. As a result, the design will be able to become more efficient,
defect-free work that will satisfactorily perform its end function.
Meanwhile, O’Connor et al. (1987) has illustrated some principles for
simplifying the designs, they are:
a) Using a minimum number of components, elements or parts for assembly.
b) Using readily available materials in common sizes and configurations.
c) Using simple, easy to execute connections with minimum requirements
for highly skilled labour and special environmental controls.
d) Employing designs which allow for field capability for dimensional
adjustment.
e) Employing designs which minimize construction task interdependencies.
However,
sometimes
the
project
objectives
may
supersede
the
constructability requirements, such as the aesthetics, operability, maintainability
and/or safety override the design simplification. In Nima et al. (2004) study stated
that the aesthetics value is one of the main project objectives of the Kuala Selangor
cable-stayed bridge, which it had override the design for simple assembly principle.
For this reason, implementation of this principle was preserved for the approaches
only and constituted a high percentage of the total cost of the project. Such actions
applied were:
33
a) Using the prefabricated post-tensioned I-Beams for the decks reduced the
usage of scaffolding,
b) Decreasing the number of elements, and
c) Using
the
prefabricated
girders
to
reduce
construction
task
interdependencies. For example, work on the cast-in-elements could
proceed while fabricating the girders off-site is in progress
2.7.4
Encourage Standardisation/Repetition
To improve the constructability during the design phase, the design of
building elements and detail should encourage appropriate standardisation or
repetition in order to reduce learning time and speed of construction. It is practically
for the enhancement of standardisation by using standard, readily-available materials
or items, so as to reduce the costs and the increased risks of error involved in the
construction. Besides, according to O’Connor (1987), standardisation of components
is based on recognition that savings can be realized when the number of variation of
components is kept to a minimum. For example, the material types, construction
details, building system, dimension and elevations can all be standardized in order to
improve the field operation efficiency.
Nonetheless, standardisation may require an addition step in the design
process. The designer would require to analyze the design and identify the elements
that have the potential to be standardised. While, the standardised elements also may
required additional design effort to accommodate all uses or vendor standard may be
employed with the selection of off-the-shelf materials.
Some applications of this principle were suggested by O’Connor et al. (1987)
in their study, briefly as:
34
a) Maximize the use of manufacturer’s standard in the selection of piping
system components, thus minimising the number of variations used in
such items as valves and pipes support.
b) Unique connections in the design of steel structure should be avoided in
attempts to save a slight amount of structural steel. Normally, beam and
bolt sizes are well suited to standardisation.
c) Standardise the electrical or instrumentation accessory items and their
details, such as hangers/supports and instrument stands.
d) Location standardisation, such as consistent elevation heights or use of
designated zones.
e) Minimise the number of different foundation sizes, so that it permits the
maximum reuse of formwork. The number of types and lengths of anchor
bolts should also be minimised.
f) The detailed design of pipe hangers often introduces more problem with
coordination than it saves in material. Thus, the design should specify
standard rod hangers and filed personnel should adjust the length to fit the
existing conditions.
2.7.5
Design for Pre-fabrication, Pre-assembly or Modularisation
Constructability can be enhanced if the pre-fabrication, pre-assembly and
modularisation of design are considered during the early design stage. Tatum et al.
(1985) defined pre-fabrication, pre-assembly and modularisation as:
•
Prefabrication is a manufacturing process, generally taking place a
specialised facility, in which various material are joined to form a
35
component part of a final installation. Pre-fabricated component often
involve the work of a single craft.
•
Pre-assembly is a process by which various material pre-fabricated
components and/or equipment are joined together at a remote location for
subsequent installation as a unit. Pre-assembly often involves decoupling
sequential activities into parallel activities and often require work by
multiple crafts.
•
While, a module is a product resulting form a series of remote assembly
operation; it is usually the largest transportable unit or component of a
facility. Modules may contain pre-fabricated components or preassemblies and are usually constructed away from the job site.
The benefit of pre-fabrication, pre-assembly and modularisation typically
include improve construction task productivity, parallel sequencing of activities,
increase the safety on site and reduced the need for scaffolding during the
construction. Nonetheless, the designation of pre-fabrication, pre-assembly and
modularisation also have its disadvantages, such as additional management
challenges, the need for support facilities, and an increased likelihood for
misalignment or damages.
In addition, O’Connor et al. (1987) stated that the pre-fabrication, preassembly or modularisation work scoping is the identification of project components
that may be beneficially constructed or fabricated away from the final workface.
These scoping studies involve an analysis of cost and benefits. Besides, once prefabrication, pre-assembly and modularisation efforts have been scoped, the design
support also should be provided by the designers, so that the designs were configured
to facilitate their fabrication, transportation and installation. In this study, O’Connor
also highlighted five important factors that might need to be concerned by the
designer while using this principle, they are:
36
a) Temporary structural support;
b) Dimensional accuracy;
c) Minimisation of scaffolding needs;
d) Sequence of operations; and
e) Design standardisation wherever possible.
In the West Port Highway project studied by Nima et al. (2002), it had been
recognized that this project had the potential of having its detailed design for the
modules and preassemblies prepared so as to facilitate their fabrication,
transportation, and installation. It is because the major part of the project consisted of
an elevated highway structure. In order to apply this constructability principle, the
consultant used prestressed M-beams and U-beams for the spans that made up the
elevated highway and post-tensioned I-beams for the intersections with the town
roads and railway tracks. However, as O’Connor et al. (1987) warned, the lifting
limitations and delivery route restrictions should be studied when planning to
implement this principle. Besides, the design should facilitate lifting, jacking and
rolling needs. Transportation accelerations should be accommodated with an
additional structural bracing, and method should be devised for minimizing the
potential for damage. Otherwise, the contractor will encounter many difficulties or
problems to construct it.
2.7.6
Analyse Accessibility of the Jobsite
Constructability is enhanced when the detailed designs promote the
accessibility needs of manpower, construction materials and equipment. This is often
a crucial consideration when a construction needs to be carried out within or pass
through the congested city area. Sometimes, the effects of poor accessibility can be
quite serious, as like delays in work progress, slowed construction productivity and
increased damage to completed works.
37
According O’Connor et al. (1987), jobsite accessibility can be a problem for:
•
Projects located on tight sites or where road capacity is limited.
•
Additions or modifications to existing plants, where material is threaded
into congested areas or work is restricted due to operations.
•
Work at high elevation.
•
Late placement of major equipment.
•
Jobsites with steep grade changes.
•
Jobsites located adjoining to other projects under construction.
•
Jobsites with extreme environment conditions, such as weather, soils or
vegetation.
•
Above-ground work when nearby underground work remains incomplete.
•
Restricted jobsites where heavy lifts are underway or are planned.
•
Projects involving multiple main contractors.
Besides, Griffith and Sidwell (1995) cited that efficient access for both
materials and personnel is essential, as is efficient existing from the site. Normally,
the jobsite accessibility is affected by the need for traffic control in two ways:
a) To bring onto the site labour, plant and materials, to off-load handle
and store materials and equipment, and to deliver materials,
components and plant to the workplace as work proceeds.
b) To remove surplus excavated materials and debris, and to move plant
and equipment of site when finished with.
Generally, Griffith and Sidwell (1995) highlighted the main points to be considered
for jobsite accessibility are how items will be brought onto and removed off the sit,
and how the design solution, construction method and sequences affecting the first
aforementioned criteria.
38
As refer to Figure 2.4, it is a project example of proposing an academic
facility building by using steel framed system, explained by Griffith and Sidwell
(1995). The accessibility to the site was carefully considered to avoid hindrance to
the existing main road and access roads around the development. The consultant has
utilised one access point throughout the site. Free access around the building was
consciously determined, and to this end the location of site hutting, permanent plant
and storage of materials was not permitted directly around the perimeter of the
building. Besides, the consultant planned to leave an unoccupied site space between
the proposed development and the existing building (left-hand-side) to allow open
construction access.
Figure 2.4
Steel-framed system build project: ground-floor plan (Adapted from
Griffith and Sidwell, 1995)
39
2.7.7
Employ Any Visualisation Tools Such As 3D CAD to Avoid Physical
Interference
Constructability is improved when the designers employ visualisation tools to
visualise any possibility of physical interference during the field operation. One of
the most common visualisation tools preferably being utilized in construction
industry is the computer-aided-design (CAD). There are many benefits to using CAD,
particularly 3D CAD to automate existing technical construction services such as
preparing estimates and schedules and building simulation models. These include
increased timeliness and accuracy of drawings, improved communication of
technical information, and increased field productivity (Mahoney and Tatum, 1994).
In the architecture, engineering and construction industries, computer
visualization usage can cover the whole lifecycle of a product from presentation of
initial concepts to the final stages of production and can also extend to maintenance
issues (Bouchlaghem et al., 2005). Generally, three dimensional walkthroughs can be
created from hand drawn sketches at the very early stages of the design process.
Then, three dimensional models can be used by design teams to communicate design
intent to client and users and to compare and evaluate design options. During more
advanced stages of design, three dimensional representations can be used to check
the buildability of the design, such as check for the integrity of services coordination,
accessibility and maintainability. Therefore, utilisation of visualise tool during the
design stage can bridge the gap between designers and site teams in facilitating the
exchange of information for constructability problems.
In addition, Ganah et al. (2000) highlighted that computer visualization
allows investigation to iron out difficulties that may occur before construction
commences on site. The spatial relationships between elements in design can be
observed and judged by eye. While the common constructability problems that can
be solved by employing visualization tools are interfaces between component and
difficult assembly.
40
2.7.8
Investigate Any Unsuspected Unrealistic or Incompatible Tolerances
Constructability is enhanced when the designers investigate any unsuspected
unrealistic of incompatible tolerances from the design they produced prior the
commencement of the construction. Adams (1989) claimed that the design of the
building assembly should recognised the sensible tolerances which are normally
attainable in site construction, by making allowance for the differences between fine
factory tolerances and to those of normal site construction. Particular attention
should be given to the problems of fit during the project design stage, which the
incompatible tolerances occur at the interfaces between different products, methods
of construction, materials and method of manufacture, and suitable jointing methods
that should be adopted.
An example described by Adams (1989), about the design bearings for steel
beams on block walls. Figure 2.5a shows a standard detail for an in-situ concrete
padstone with ragbolts, which designed to receive a steel beam and spread its load
into a weak insulating block skin. The original design detail provided by the designer
allows no tolerance if the wall being built slightly out of position. If necessary, an
alternative detailing can be proposed, which slotted holes in the beam flange (Figure
2.5b) will at least allow easy location of the beam over the ragbolts, even if the wall
is out of position.
Figure 2.5 : Steel beam on block walls (Adapted from Adams, 1989)
41
2.7.9
Investigate the Practical Sequence of Construction
Constructability is enhanced if the designers give an adequate consideration
of practical sequence of construction during the design stage. The designers should
bear in mind that the method of a construction project should encourage the most
effective sequence of building operations. The effective sequences which mean the
simple sequences that enable each operation to be completed independently and
without interruption. Besides, the sequence should assist the co-ordination of trades
and minimise any delay to the works.
According to Oberlender (2000), sequencing of installation is as much a
design consideration as it is a procurement and construction consideration. Many
times designs have evolved that unnecessarily restrict installation sequences during
the construction stage. Hence, the designs should carefully consider the layout and
spacing of facilities, so that more than one construction operation can occur at a time.
From that, it will able to improve the constructability and reduce the construction
time.
In another example, Adams (1987) showed that under the initial proposal the
erection of the infill walling was a prerequisite for sealing the roof, as in Figure 2.6a.
Although non-loadbearing, the walls would delay progress on the installation of
gutters, fascias, services, and even the ground slab. Therefore, by initially complete
the steel structure’s support frame, the walling can became a non-critical element
which could follow later in the sequence of operations, without hindrance to the rooflevel services (Figure 2.6b). Besides, the walling itself can have a smoother operation
when its turn in the sequence came due to the extra protection provided by the rooflevel services.
42
Figure 2.6
Revised scheme for practical sequence of construction (Adapted from
Adams, 1989)
2.7.10 Plan to Avoid Damage to Work by Subsequent Operations
Early consideration and plan to avoid damage to work by subsequent
operations during the design stage can enhance the constructability. This principle
advocates the design should enable work to be carried out in a workmanlike manner
without risk of damage to adjacent finished elements and with minimum
requirements for special protection.
43
Adam (1989) given an example of the application of this principle where the
steelwork for the frame building had to be designed and fabrication drawings had to
be finalised as soon as the architect’s drawing were complete. The ceiling finishes
were at the level of the bottom of the beam flange in order to minimise floor depths.
Therefore, holes would be required in the beams to accommodate services, however
there were no detailed service drawings available at this stage. The work would
become costly if the services holes were ignored at the design stage and allow them
to be cut on site after all the service drawings were available and the structure
engineer had checked the effects of such holes. As a result, extra strengthening and
paint protection works for such holes would be required to overcome the weakness in
the structure caused by the holes. Therefore, Figure 2.7 shows an alternative solution,
where the designer should discuss with architect and M&E engineers about the
problems, predict the service runs, design for the holes, and included them on
fabrication drawings.
Figure 2.7 : Typical floor beam with service holes (Adapted from Adams, 1989)
According to Rosli (2004), the application of this constructability principle
requires the designer to be imaginative of the impact of the selected design on
damage to other operation. Hence, some heuristic knowledge is essential for the
designer during the evaluation of the design solution with respect to this principle.
44
2.7.11 Consider Storage Requirement at the Jobsite
It is frequently said that a ‘neat and tidy site is an efficient and well-run site’.
Unfortunately, the practicality of daily construction means that many sites are
generally untidy (Griffith and Sidwell, 1995). Thus, consideration should be given at
the design stage to the location of material storage and unloading facilities, in order
to improve the project constructability. Particularly, it is frequently necessary on
congested site to phase the construction works so as to facilitate the use of part of the
site or building for storage purpose. Whilst, the things that normal occupied the site
space are building materials, building accessories, plants, scaffolding, shoring,
formwork and maintenance tools.
Four essential aspects of materials storage that related with constructability
are (Griffith and Sidwell, 1995):
a) Reduction of multiple handling of materials.
b) Protection of materials from damage by weather.
c) Prevention of damage either to material or to finished work by nearby
production and/or through general carelessness.
d) Prevention of damages and loss that result from handling and stacking
materials during delivery, storage and movement around the site.
2.7.12 Investigate the Impact of Design on Safety During Construction
Constructability is enhanced when the designer properly consider and
investigate the impact of design on safety during construction. The design should be
arranged so as to promote safe working environment, especially for the earth works,
foundation construction, works that worksite are on below ground level and high
elevation works. In addition, the design should consider the impact of design on
safety when materials and components are being handled, and wherever traversing
45
for access is necessary. While in renovation project, the designer also should
consider the risk of accidents that arose from existing elements
An example described by Adams (1989) that the safety of temporary works
not only is the contractor’s responsibility, but also the designer too. It is because,
sometimes, the designer has the option of choosing a specification which is
inherently safer than the other alternatives. Figure 2.8a and Figure 2.8b illustrated
that there were two alternative designs could be choose by the designer in a capping
construction of a coal mineshaft. Figure 2.8a shows the first alternative that the cap
can be constructed by using cast insitu concrete, while another alternative is use steel
grillage cap (Figure 2.8b). In order to give consideration to safety of the worker and
construction, the second alternative design could be adopted. It is because it is safer
rather than allowing the steelfixers and carpenters enter to the shaft, which required
extra support for the excavation.
Figure 2.8(a, b)
Two alternative designs for capping of a coal mineshaft
(Adapted from Adams, 1989)
46
2.7.13 Design to Avoid Return Visit by Trade
Constructability is enhanced when the design considered the arrangement of
work sequence in such a way that a trade or specialism can complete all its work at a
work place with as few return visits as possible. An example of development within
an historic terrace described by Adams (1989), where the exposed walls of the
historic terrace house would be in need to support once a building structure beside it
was demolished. Traditionally, the old structure would be open up enough to allow
shore to be placed. Then the demolition could be carry out; construct the new
structure frame; remove the shores; and lastly complete the floor bays left out to
accommodate the shores. Significantly, there were return visits for the provision and
removal of the raking shores.
Alternatively, with considering the design to avoid return visit by trade
principle, the first bay of the replace structure could be designed as a rigid frame, so
that it able to provide both temporary and permanent support as depicted in Figure
2.9. Thus, it eliminated two visits by a complete trade (specialist scaffolding) and
this design is more practical and cost effective for the particular layout of the existing
structure than the traditional design mentioned above.
Figure 2.9
Elevation showing proposed development within an historic terrace
(Adapted from Adams, 1989)
47
2.7.14 Design for the Skills Available
Technology and skills availability are often not considered early enough in a
project life cycle. The availability of technology, labour and the skill level of the
workers and the contracting organization should be fully explored. Therefore, the
designer should design for the skills available in order to improve constructability of
the project. It is because the absence of either skill levels or availability of the work
force can have a costly impact on a project and require consideration during the
design phase (Oberlender, 2000).
Griffith and Sidwell (1995) stated that the designer must not design for the
explicit skills of a particular workforce, because that would be an ideal case, but in
general he/she must anticipate the levels of skill likely to be available within a
modern contracting organization’s workforce, and should design it within their
capabilities. Meanwhile, according to Adams (1989), any design is only as good as
the skills available to execute it, either off-site or on-site. Hence, the design must
comprise a realistic assessment of the levels of skill likely to be available form
appropriately chosen contractors and specialists.
2.7.15 Consider Suitability of Designed materials
Constructability is enhanced when the designer carefully selected the
products, material and its specification. It is recommended that the designers should
select products and materials that have been proven suitable to be used. Besides, the
products and materials should be selected which they utilise normal site assembly
methods and sequences, with subsequent operations and wear and tear in mind. Care
also should be taken to ensure that manufacturer’s recommendations on handling,
storage, application, assembly and protection can be complied with.
48
According to O’Connor et al. (1987), design basis or job specification should
communicate preferred design details, but not overly constraining design
configuration, or the equipment or materials selection. Besides, constructor input
should be sought in the identification of preferred materials. For instance, if the
constructor preferences vary, specifications should allow for and cost-effectiveness
alternatives. O’Connor et al. (1987) also cited that the usage of material which is
difficult to obtain should be avoided. In addition, misapplication of material
specifications is another problem to constructability. The use of improper standards
or code-excessive specifications can be costly and discourages cost-effectiveness
when perceived as gold-plating, likes requiring machine-like tolerance where
unnecessary and designing the service conditions which do not exist such as high
temperature or high pressure.
Hence, improper consideration of material selection and applications would
impact the project constructability, and resulting in costly modification if the
construction is commenced. However, these impacts can be lessened and eliminated
when the designer addressed during the design phase by implementing this
constructability principle.
2.7.16 Provide Detail and Clear Design Information
Designer provide detail and clear design information, such clear detailed
drawings,
product
and
materials
specification
and
dimension,
prior
the
commencement of construction will able to improve the constructability of the
project. However, preparation of detail and clear design information required
sufficient time and resources, and these requirements must be allowed from the
design budget (Adams, 1989). Besides, complete project information should be
planned and coordinated to suit the construction process and to facilitate the best
possible communication and understanding on site.
49
2.7.17 Design for Early Enclosure
Constructability is enhanced when the design facilitate enclosure of the
building as early as possible. Early enclosure of the building (either early completion
the roof or building shell) is desired so that the following operations can then
commence early in the work programme and they can be carried out without
hindrance from the weather. Normally, ground-floor slab concreting, floor and wall
cladding, building accessories installations and painting are required the early
completion of roof, in order to received the protection and ensure smoothness of the
works under unfavourable weather conditions. Alternatively, the designer can make
use more pre-fabricated, pre-assembly and/or modularisation components in the
building design so that the structural construction can be speed up and achieve the
early enclosure of the building.
As refer back to Figure 2.6a, it shows the initial plan of the gutter and fascia
detail, where the gutter relied for its support on a small steel angle fixed to the face
of the brick work. It is significantly showed that the gutter could not be formed until
the non-loadbearing brick walls were built up to the roof level. Thus, the design
prevented early sealing of the roof and therefore would delay the early enclosure of
the building. Hence, alternative solution was proposed under this principle in stead of
the constructability principle mentioned in section 2.7.9. New design solution in
Figure 2.6b shows that complete sealing of roof including the gutter could be
achieved immediately after the steel frame was erected.
2.7.18 Consider Adverse Weather Effect in Selecting Materials or Construction
Method
Constructability is enhanced when the designers consider the adverse weather
effect in selecting materials and/or construction method during project design stage.
Commonly, the designer and constructor would face a greater challenge when the
construction project located at the adverse weather environment. O’Connor et al.
50
(1987) claimed that designers should investigate ways in which the exposure to
temperature extremes and the effect of rain may be minimised.
Under this constructability principle, O’Connor et al. (1987) suggested some
specific applications:
•
Incorporate designs that enable early enclosure to permit construction
works can be proceed when the weather becomes harsh.
•
Designs for allowing large enclosed spaces to double as fabricating shops
and equipment storage during construction.
•
Promote early paving of the site to eliminate muddy operations.
•
Specify concrete admixtures and curing techniques to overcome the
effects of extreme heat, cold or high wind.
•
Maximize the offsite work, by promoting utilisation prefinished materials.
Within the West Port Highway construction in Malaysia that studied by Nima
et al. (2002), this principle was practiced through using the precast units for the
girders and drainage systems for roadsides and manholes. It was because the precast
elements were not damaged by rain when compared with the cast-in situ type of
construction. Moreover, the designer designed the drainage systems by using the
precast elements did helped in discharging rainwater during rainy weather.
2.8
Summary
From the literature review of the constructability principles in construction
building project, it can be concluded that various organization and individuals have
defined the constructability term and developed the principles of constructability in
their researches. In overall, those constructability definitions stress the important of
overall project objectives, while some directly addressed the design-construction
interface.
51
In addition, the developments of constructability principles among those
researchers are varied, in term of implementation the constructability in different
project life cycle stages, and the local environment of their national construction
industry context. Therefore, those principles are not universal and any adoption of
those principles should depend and fit to project requirement and local environment.
Although the CIRIA and CII constructability principles cover all project lifetime, but
their applications are too general and difficult to apply and evaluate the
constructability improvement in a building project’s design phase.
Thus, the design phase’s constructability principles that used in this study are
adopted from Rosli (2004), where these principles are more thorough with respect to
ease of construction. These design phase constructability principles are resulted from
a collaboration of the design phase’s constructability principles found by various
researches mentioned above. These eighteen design phase’s constructability
principles, named from P1 to P18, are highlighted as following:
•
Principle P1: Carry out thorough investigation of the site;
•
Principle P2: Design for minimum time below ground;
•
Principle P3: Design for simple assembly
•
Principle P4: Encourage standardisation/repetition;
•
Principle P5: Design for pre-fabrication, pre-assembly or
modularisation;
•
Principle P6: Analyse accessibility of the jobsite;
•
Principle P7: Employ any visualisation tools such as 3D CAD to
avoid physical interference;
•
Principle P8: Investigate any unsuspected unrealistic of incompatible
tolerance;
•
Principle P9: Investigate the practical sequence of construction;
•
Principle P10: Plan to avoid damage of work by subsequent
operations;
•
Principle P11: Consider storage requirement at the jobsite;
52
•
Principle P12: Investigate the impact of design on safety during
construction;
•
Principle P13: Design to avoid return visit by trade;
•
Principle P14: Design for skills available;
•
Principle P15: Consider suitability of designed materials;
•
Principle P16: Provide detail and clear design information;
•
Principle P17: Design for early enclosure; and
•
Principle P18: Consider adverse weather effect in selecting materials
or construction methods.
53
CHAPTER 3
RESEARCH METHODOLOGY
3.1
Introduction
This chapter discuss the research methodology adopted in this study in order
to achieve the objectives discussed in Chapter 1. As illustrated in Chapter 1 (Figure
1.1), this research methodology consists of three distinct phases, which are phase 1,
phase 2 and phase 3 respectively. Generally, phase 1 involves determination of the
objectives and scope of this study, literature review and preliminary interview. Phase
2 involves information collection and investigation of the local current design
process, and design phase’s constructability issue, in order to develop a current
design process model of building construction by adopting the data flow diagram
(DFD) technique. While in phase 3, it involves a proposal of design process
improvement by integrating with design phase’s constructability principles, and
constructability design review checklist. Besides, the improved design process and
checklist will be review by the experts so that an appropriate design process
improvement and constructability review checklist are produced. Nonetheless, detail
description of research methodology and process involved in each phase of this study
are further discussed in following section.
54
Determine Objective
and Scope
Phase 1
Preliminary Interview
Literature Review
Case Studies
-
Investigate local current design process
-
Constructability issue
Phase 2
Develop Current Design
Process Model
Integrating Constructability
into Design Process
Develop Building Design
Constructability Checklist
No
Review by Experts
Yes
Conclusion / Recommendation
Figure 1.1 : Schematic of research methodology
Phase 3
55
3.2
Phase 1
3.2.1
Determine the Objectives and Scope
Prior to the determination of this study’s objectives and scope, early readings
on those topics and discussions related to constructability in construction industry are
essential. It is because it able to give a general concept and understanding to the
basics of the work that desire to be carried out. Almost all of the readings are
obtained by using the facilities provided from the Universiti Teknologi Malaysia’s
main library (Perpustakaan Sulatanah Zanariah – PSZ). After several readings have
been carried out, the topic, objectives and scope of this study are discussed and set
with the guidance from author’s supervisor, Dr. Ir. Rosli Mohamad Zin. After that,
the study is continued with the literature review.
3.2.2
Literature Review
In this stage, the main aim of carrying out the literature review is to review
and obtain information and knowledge of this topic from previous studies and
researches, such as articles, journals, paperwork, reports, thesis and also some
relevant books. Basically, it covers various definition of constructability term,
development of constructability principles and concepts throughout project life time,
constructability review and designer responsibility during the design stage, and
process involve during the design phase. Most of the reading materials were obtained
the PSZ, while some were given by Dr. Ir. Rosli Mohamad Zin.
56
3.2.3
Preliminary Interview
According to Fellows and Liu (1997), there are three types of interview
techniques:
•
Unstructured interview;
•
Semi-structured interview; and
•
Structured interview.
In an unstructured interview, the interviewer introduces the topic briefly and
the respondent will answer the theme proposed by the interviewer. Meanwhile, the
interviewer records the replies of the respondent. The advantages of unstructured
interview are it able to uncover the important concepts that can eventually guide
future enquiries and insight into general problem. Then, in a structured interview, the
interviewer needs to administer a questionnaire, probably by asking question and
recording the responses by using the note taking and/or tape recorder method. The
advantages of structure interview are the attention is focused on a given issue and
detailed information is gained on issue discussed. While for the semi-structure
interview, it fills the spectrum between the structured and unstructured interview.
Semi-structured interviews is suitable to be carried out in a situation where broad
issues may be understood, but the range of respondents' reactions to these issues is
not known or suspected to be incomplete. This type of interview is mostly applicable
in situations where both qualitative and quantitative responds are required.
In this stage, the unstructured preliminary interviews are adopted to obtain
the opinion of the designers and contractors with regard to constructability and
design-related problem. During this preliminary interview stage, the engineers from
consultancy firms who have minimum of four years experience in project design and
contractors that have minimum of four years experience in project construction are
interviewed. From those responses, the author will able to be more understand on
these issues and therefore helps the author to scope out and design the interview
questions which will be carried out in next phase.
57
3.3
Phase 2
According to Fischer and Tatum (1997), interviews proved preferable to
questionnaires as the knowledge acquisition method because they allowed direct
interaction between the expert and the interviewer. Besides, a personal interview
process was the best data collection technique for the type of detailed information
required (O’Connor and Miller, 1993). Therefore, information about the current
practice of the design process in building construction is collected by interviewing
the experts. In this section, details of the interview questions are described. In
addition, the data flow diagram technique adopted to develop current design process
model based on and combined with those information collected is also explained.
3.3.1
The Interview
As mentioned above, there are three types of interview techniques can be
adopted for information collection of a research or case study. This stage involves
the actual and detailed information collection on the local construction industry’s
current design process, therefore structure interview is adopted.
Basically, three consultant engineers and one architect who have at least eight
years of experience in design process, and currently working and practicing their
expertise, respectively in a civil and structure consultancy firm and architect firm
have been interviewed. These four designers are interviewed with the objective of
investigating and identifying typical information related in the design process, which
based on traditional procurement system building project that they had been carried
out. Those fours interviewees are regarded as the experts in this study. Besides, in
order to gather more detailed information of design-related constructability problems
in construction, one contractor (has minimum five years experience in building
construction), and one clients are interviewed for the opinion and suggestion.. Table
3.1 summarized the basic selection criteria in determining the interviewees.
58
Table 3.1 : Basic selection criteria in determining the interviewees
The experts
Other interviewees
Civil engineer
Architect
Contractor
Developer/Owner
3
1
1
1
8 years
8 years
5 years
Not specified
C&S
Architect
Building
Not specified
consultant
firm
contractor
No. of person
need to be
interviewed
Minimum
experience
Types of firm
Generally, the scope and topic of the interview questions that will be covered
during interviewing the experts are:
•
The common number of stages or sub-phases that involve in a design
phase.
•
The actual flow of design processes that currently being practice in a
building project among those stages.
•
The design-related problems
•
The suitability and series of review design constructability process at
various milestones should be conducted in the design phase, e.g. 60% or
90% of design completion.
•
Features should be reviewed or checked in the review design
constructability process to enhance the project constructability.
According to Kvale (1996), the methods of recording interviews for
documentation and later analysis include audiotape recording, videotape recording
note taking, and remembering. The usual way of recording interviews is with a tape
recorder, where it lets the interviewer concentrate on the topic and the dynamics of
the interview. A videotape recording will encompass the visual aspects of the
interview, particularly for analyzing the interpersonal interaction in an interview.
59
While for remembering, there are obvious limitations to a reliance on memory for
interview analysis, such as the rapid forgetting of details and the influence of a
selective memory. Therefore, in this study, both the note taking and electronic sound
recording method are adopted during the interviews due to its simplicity and
reliability.
3.3.2
Develop Current Design Process Model
After the interview stage, the information, opinions and suggestions obtained
from the experts are used to develop current design process data flow diagram. Each
model is developed with regards to each case study. In this study, the author named
those models as “current building design process model”, in order to avoid confusion.
Then, those four current building design process models are compared, combined
and generalized to develop a general current design process model, which named as
“general building design process model” in this study, prior proposing of any
constructability integration. Series of reviewing and refining were conducted through
discussion with the pre-appointed experts, in order to ensure the correctness of the
models. Hence, the modelling technique used in this case study is data flow diagram
(DFD) and its methodology is discussed in details at the following section.
3.3.2.1 Data Flow Diagram (DFD)
Data flow diagram (DFD) is used in this case study to model the current
design processes and information exchange between them. According to Ramli and
Mesir (2004), data flow diagramming is a means of representing a system at any
level of detail with a graphic network of symbols showing data flows, data stores,
data processes, and data sources/destination. The DFD methodology was selected
because of its simplicity of use and the fact that the components can be translated to
the relevant elements in the design process. The components of DFD and their
interpretation in the design context are shown in Table 3.2. The processes represent
60
design tasks, the data flow arrows indicate the flow or exchange of information and
the data stores standards, specifications or design files. Data sources or sinks are used
to represent external entities or organizations such as the architect, the client, the
contractors or local authorities.
Table 3.2
Components of a data flow diagram for design (Adapted from
Baldwin et al., 1999)
Element
Data or info. flow
Software development
Design process
description
modelling description
A connection between
Design information flow
processes, etc., representing an
input and/or an output
Process
Individual functions that a
Individual design task,
system carries out. They
e.g. calculation, drawing,
transform an input into an
specifying
output
Data store
A collection of information that
Drawings, sketches,
must be remembered for a
calculation files, reports,
period of time
documents,
specifications, computer
files, etc.
Source/sink
External entities with which the
Any external data source,
system communicates
e.g. client, local authority
In the study of a data flow model of the building design process conducted by
Baldwin and Austin (1996), they claimed that the DFD technique has three
characteristics that make it an appropriate tool to model a system consisting of
processes or tasks linked by interfaces, particularly the building design process.
61
a) DFDs view systems from a data or information point of view: They map the
journey of information through a system, recording its transformations and its
coordinations. DFDs do not impose or record any managerial control on the
timing of the flow of information and subsequently do not dictate an order in
which the tasks should be performed. This allows tasks that form part of an
iterative cycle to be modelled and understood. This is essential as design is an
iterative process and can rarely, if ever, be performed as a series of sequential
processes, especially in a multi-disciplinary project. DFDs allow us to look at
a system of coupled tasks (tasks that require solving iteratively) and gain a
clearer understanding of the information transfer mechanisms without any
preconceived ideas of order.
b) DFDs do not require processes to be modelled: Each design task can be
treated as a ‘black box’, with only the information input and output being
studied. This allows analysis of information flows and transformations
without having to model the individual design tasks.
c) DFDs can be layered or ‘partitioned’ by breaking each task down into
subtasks, where each DFD is restricted to an A4 page, producing a compact,
multidimensional DFD model. The data flow diagrams are drawn in a
hierarchical form. The top level of the model, known as ‘context diagram’
represents the design process in the most general of terms. Then, the context
diagram is subdivided and the processes further decomposed until the
decomposition identified the tasks that produced specific information
requirements. Hence, this allows the higher regions of the model to be read to
obtain an overview of the system, and, if more detail is required, the lower
levels can be studied as and where necessary. DFDs can be constructed top
down (subdivision of tasks) or bottom up (aggregation of tasks).
62
3.3.2.2 Drawing A Data Flow Diagram
Ramli and Mesir (2004) had suggested several steps to construct a successful
data flow diagram, which it will be adopted in this study for developing the those
current design process model. These steps are highlighted as following:
a)
Start with the context diagram showing all outputs and inputs of a
system.
b)
List all the events that affect the system (perhaps showing these events
on the context diagram). Each event will generate some input that the
system must handle or required the system to generate some output.
c)
Normally, a large system will have a large number of bubbles
(processes) at the context diagram. Therefore, the bubbles should be
grouped by subsystems that show the overall skeleton of the system.
d)
Then, further level the DFD. Some of the partitioned process might be
too simple to be levelled further; while other might need one or two
more levels of details. Hence, it can be done by working from the input
to the output or from output to the input to identify the activities
involved in each process.
e)
Be precise in identifying new data flow and data store by giving them
precise name and stick to two words if possible.
f)
Make sure that the diagrams are agreed by the experts before further
into details.
g)
Show data rejects and errors as small stubs (a cut off) rather than a data
flow, so that it can simplify the DFD.
h)
Try not to flowchart the data flow.
i)
Problems of initialisation (opening files) and of termination (closing
files) are ignored. These are considered as terminators and will be
considered at the design stage.
j)
Several trials may be required before achieving the final diagram.
Therefore, several reviewing from predetermined experts to those
completed design process DFDs are required during the development of
final diagram.
63
3.4
Phase 3
After the “general building design process model” is developed, the following
steps are needed to be performed in order to achieve the study objectives.
•
Proposing a review design constructability process in that “general
building design process model” by inserting constructability inputs and
review process at the appropriate stage suggested by the four experts.
•
Developing a building design constructability checklist for assessment on
building foundation designs which it is a tool that can be used as
constructability inputs and for reviewing the design constructability.
•
Reviewing of that constructability integrated building design process
model and constructability review checklist by the four experts who have
been determined previously.
3.4.1
Integrating Constructability into Design Process
Figure 3.1 illustrated the schematic of constructability integration into design
process. Before proposing any integration of constructability into the design process,
it is necessary to identify the existing and absentee of constructability review process
in that “general building design process model”. Besides, based on the information,
opinion and suggestion given by the experts in phase two, an integration of review
design constructability is proposed into the “general building design process model”
at the appropriate stage of the design processes. Then, a new current design process
model that presented in DFD form, which the author named it as “constructability
integrated building design process model” is developed. Lastly, the “constructability
integrated building design process model” is reviewed and checked by the four
experts for its appropriateness. Several trials had been done in order to obtain an
appropriate “constructability integrated building design process model”.
64
Start
Identify existing and absentee of
constructability review process in
“general building design process model”
Identify the appropriate time for inserting
constructability inputs and reviewing
design constructability
Propose a review design constructability
process into the “general building design
process model”
No
Check for
appropriateness
OK
Finish
Figure 3.1 : Schematic of constructability integration into design process
3.4.2
Constructability Design Review Checklist
Due the limit of time, only a building design constructability checklist for
assessment on foundation design is developed. This checklist acts as a tool for
designers to know what features need to be considered before beginning their design
works, and check and assess the design work before its completion. Hence, items or
65
features to be checked are listed out in that building design constructability checklist
form, where the design constructability principles that applicable to foundation
design are already been inserted in it. So, when the designers study through and
check those features, they are automatically considered and reviewed for design
constructability. Besides, the Ok and not Ok columns, and remarks columns also
were constructed in the checklist.
3.4.3
Review by Experts
Finally, together with the “constructability integrated building design process
model”, the building foundation design constructability checklist are checked by the
four pre-appointed experts (3 engineers and 1 architect), in order to check for its
mistake and to ensure for its appropriateness. Inevitable, several trials and correction
have been tried for developing a suitable building foundation design constructability
checklist.
3.5
Summary
This chapter describes the research methodology in those three phases that
will be used in this study, where it comprises literature reviews, interview,
development of design process models, constructability improvement and checklist
development. Based on the discussions that have been presented at above, the
summaries of this chapter are:
a) Unstructured interview is adopted during the preliminary interview, in
order to obtain the opinion from the designers and contractors with regard
to general constructability and design-related problem, where the
designers and contractors are not necessary an expert person.
66
b) During phase two, the structured interview is used to investigate and
collect information about the local current design process. It is conducted
by interviewing the experts and other interviewees.
c) The modelling technique used to model the collected information is data
flow diagram (DFD).
d) All building design process models, constructability integrated building
design process model, and foundation design constructability checklist
were reviewed by the predetermined experts in order to check for its
mistake and to ensure for its appropriateness.
67
CHAPTER 4
DATA COLLECTION AND ANALYSIS
4.1
Introduction
This chapter presents the interviewees’ responses that gathered through the
structured interview, the analysis of the four case studies, development of the general
current design process model until the integration of constructability into the design
process, and development of checklist for foundation design.
Basically, architects and the structural engineers are the major parties who
execute the project design work. By according to the sequence of the design work
flow, the author presents the architectural building design process first before
demonstrating the engineering building design process. Therefore, there are a total of
four case studies which named as the architect firm #A1, the civil and structural
consultancy firm #C1, #C2, and #C3 are presented in the following sections.
4.2
The Architect Firm #1
A medium size of architect firm in Johor Bahru had been chosen for the data
collection exercise, which is denoted as #A1 in this study. The interviewee who the
author met, have had minimum of eight years of experience in architectural building
design. According to the interviewee, the preliminary design process begins when
68
architect meets the client, where client will express the project cost plan, his/her
requirements, such as the building concept design, material that wanted to be used
and etc to his/her architect. From that, architect will carry out some site surveys to
gather more relevant and useful site information before produce the first architectural
sketches. Meanwhile, architect may get some architectural design ideas by referring
to some architectural references. During the architectural sketching stage, architect
also will retrieve some materials details that will be used in the building, where
aesthetical, suitability, availability and cost of the material will be determined. After
that, those sketches will be presented to the client, and therefore several redrawing
may be required before achieving the final preliminary drawings that approved by
the client.
After the architectural preliminary drawing had been developed, the design
will proceed to produce the architectural schematic design. Generally, architectural
schematic design presents the layout plan, elevation and perspective view of the
building. Besides, the entire dimension and some relevant standard specification that
shows in these schematic drawings should fulfill the authorities’ requirements.
Because of some building structure may need to be built by non-conventional
method, therefore, the architect are required to save those architectural schematic
drawings in a data base which can be retrieved by the consultant engineers who work
behalf on client. From that, the consultant engineers will produce their preliminary
engineering plan, where they will bring it to the next meeting with the client,
architect and other engineers.
During the discussion, client, architect and engineers will discuss about the
building design, types of the structural system that need to be adopted, building cost,
consideration of project construction duration and etc. Consequently, architect and/or
engineers may be required to resubmit their drawings if they received feedbacks
from the next discussion. If the client agreed upon to the architecture drawings and
engineering preliminary plan, quantity surveyor will estimate the overall cost of the
building based on those drawings and market prices. Commonly, client will comment
on those drawings again if the cost feedback shows the cost of building is over the
budgeted cost.
69
The design will be proceed to the detail design stage after the completion of
cost estimating by quantity surveyor and client approved the architectural schematic
design and engineering preliminary plan. In this stage, the architect will produce
other detail architectural drawings to detail out all the standard and quality of the
building elements. After that, these drawings will be stored into the database and sent
to the consultant engineers, so that the engineers can retrieve it when they need those
detail information. Finally, the consultant engineers will produce the building
structural layout plan and submit to the architect for checking and drawing
coordination. Then, either the architect will give comments or approval, which is
depends on the correctness of the structural position and dimension to the
architectural drawing. Sometimes, client may change his/her mind, where he/she may
requests to change some of the building design. Hence, the design may need to
rework either from the produce architectural schematic drawings process or from the
engineering design process.
After the engineer had produced all their engineering drawings, quantity
surveyor will work out the whole building cost again, based on the architectural and
engineering drawings. If the cost of building is more than the budgeted cost,
therefore the design may need to be redesign again, where the design process may
start from either produce the architectural schematic drawings process or the
engineering design process. If the estimated cost is within the budgeted cost, the
client may request the engineer to produce their construction drawings for
procurement stage.
4.2.1
Model of Architect Firm #A1
Based on the above information given by the interviewee from the architect
firm #A1, the current design process model is shown in Figure 4.1a, 4.1b and 4.1c.
Generally, the preliminary design process of this case study consists of producing the
architectural sketches, producing the architectural schematic design, and discussion.
While, the detailed design process consists of producing the detail architectural
70
drawing, and producing construction drawing. On the other hand, the estimating cost
process is treating as another process (Figure 4.1b) rather than being included into
the preliminary design and detail design. Both of the materials and architectural
references serve as the storage database for the produce architectural sketches
process. Meanwhile, the drawing serves as the storage database for both preliminary
and detailed design processes in this case study. By referring to Figure 4.1b and
Figure 4.1c, the entities of this case study are the client, architect, engineer,
topographical info, authorities, and constructability.
Preliminary Design Process
Site
Information
Authorities
Requirements
Cost Plan
Materials
Arch. Schematic
Drwg.
Client
Requirements
Materials
1.2
1.1
Produce Arch.
Sketches
App. Arch.
Produce Arch.
Schematic
Design
Preliminary Drwg.
Refer
Idea
Sketches
Architectural
References
Eng. Drawings
Arch.
Drwg.
Detail
Arch. Drwg.
3.2
1.3
Arch.
Schematic
Drwg.
3.1
Produce
Construction
Drwg.
Notification
Eng.
Preliminary
Plan
Feedbacks
Drawings
Arch. + Eng.
Drawings
Construction
Drawings
Arch. Schematic
Drwg.
Comments
Arch.
Schematic
Drwg.
Produce Detail
Arch. Drwg.
Discussion
App.
Preliminary
Design
Comments
Feedback
Arch. Drwg. +
Eng. Preliminary
Plan
Cost
Feedback
Structural Layout
Plan
Comments &
Approval
Detailed Design Process
Figure 4.1a
The current building design process model #A1: level 2, preliminary
design and detail design
71
Client
Budget
Estimated
Cost
Cost
Feedback
Topographical
Info
Prices
Request
Prices
2
Estimating
Costs
Arch. Drwg.
+ Eng.
Preliminary
Plan
Arch. + Eng.
Drawings
Eng. Drawings
Architect
Site
Information
Authorities
Authorities
Requirements
Arch. Schematic
Drwg.
Engineers
Drawings
Arch. Schematic
Drwg.
Arch.
Drwg.
Arch.
Schematic
Drwg.
Detail
Arch. Drwg.
Comments &
Approval
3
1
App. Preliminary
Preliminary
Design
Eng. Preliminary
Plan
Structural
Layout
Plan
Detailed
Design
Design
Structural
Layout
Plan
Comments
Feedback
Comments &
Approval
Cost
Client
Plan
Requirements
Construction
Drawings
Sketches
Client
71
Figure 4.1b : The current building design process model #A1: level 1
72
Topographical
Info
Site
Information
Authorities
Structural
Layout Plan
Authorities
Requirements
0
Current
Building Design
Process #A1
Arch. Schematic
Drwg.
Comments &
Approval
Construction
Drawings
Comments &
Approval
Structural
Layout Plan
Budget
Comments
Sketches
Cost Plan
Client
Requirements
Feedback
Cost Feedback
Eng. Preliminary
Plan
Estimated
Cost
Engineers
Architect
Client
Figure 4.1c
The context diagram of current building design process model #A1:
level 0
4.2.2 Additional Information from Architect Firm #A1
This section describes the opinions and recommendations of the interviewee
of the architect firm #A1 to the questions number 3 to 6.
According to the interviewee of architect firm #1, consideration of
constructability and its input should be considered when the architect starts sketching
the concept of the architectural design, during the architectural preliminary design
stage. Besides, if the design constructability review process is needed to be inserted
in the design process, it is recommended that it should be reviewed before meeting
the client and consultants. In other words, it should be reviewed as early a possible,
where the review and/or design changes have not yet given significant impact to the
cost and time of the project, particularly before the building design or sketches are
presented to the client and/or consultants.
73
Regarding to the question number 5, the interviewee responded that as a
professional, the architect has the responsibility to ensure his design fulfills the client
and authorities requirements, can be easily constructable and free of error or
omission. Alternatively, it will be a serious omission if the architect did not consider
those appropriate and relevant circumstances in his design. Nonetheless, the senior
architect will guide and check the inexperience architect’s design work during the
design.
The interviewee of the architect firm #A1 selected four constructability
principals that suitable to be used and can be reviewed in architectural design works,
they are:
•
Principle P1: Carry out through investigation of the site
•
Principle P15: Consider suitability of design materials
•
Principle P16: provide detail and clear design information
•
Principle P18: Consider adverse weather effect in selecting materials or
construction method
According to the interviewee of the architect firm #A1, carry out through
investigation of site is very crucial, where the architect is needed to determine the
environment and surrounding area of the future building. For example, area of the
site, trees that need to be preserved, and types and characteristic of the soil. Besides,
when the architect is trying to fulfill the client requirement, the selection of materials
in terms of aesthetic value, suitability and economic will also be considered by the
architect during his/her is sketching and designing the building architectural. In
addition, the architect needs to ensure their design is given with clear dimension and
level, avoid any weird dimensions that need extra works during the construction and
be concise to the specification, such as the structural element’s dimension and
detailing is subjected to engineering design.
74
4.3
The Consultancy Firm
Three local consultancy firms had been selected for the data collection
exercises in this study, which are denoted as #C1, #C2 and #C3. These three
consultancy firms are located around the Johor Bahru, Malaysia, where they are
well-established medium size company and specializing in civil and structural works.
The interviewees, who the author met, have had minimum of eight years of
experience in building design work that procured under the traditional contracting
system. Sections 4.3.1 until 4.3.3 describe the interviewees’ responses towards the
interview question, respectively.
4.3.1
The Consultancy Firm #C1
First of all, it is a must for the employee in the consultancy firm #C1 to check
for the completeness of the architecture drawings, so that the architect is immediately
informed for any missing drawings and will replace it as soon as possible. It is
because such minor carelessness could not be tolerated as the cause of late starts of
the engineering design work.
Prior the beginning of the engineering design, civil engineer is required to
study the architecture drawings thoroughly. From that, he/she needs to identify
topography of the building layout, existing infrastructure and facilities, the structure
of that building, types of structural system, and any structure that require specific or
special dealing. Soil investigation report is an important tool to determine the type of
the building foundation and its design. Therefore, civil engineer must ensure that the
client conducted appropriate soil investigation and the report had been received
before the structural design started. Sometimes, site visit might be required when
there is unclear information from the drawings or the SI report. In addition, civil
engineer also needs to know and understand the client requirement, and overall cost
and material quantities that commonly used to build such a building.
75
After studying the architecture drawing, the civil engineer will sketch the prelayout plan of the building by showing the location of the beams, columns, walls,
footing and other necessary facilities that need to be constructed. In this stage, the
engineer’s design experience and knowledge play a prominent role, where they help
engineer to plan and determine the most suitable and appropriate location and
dimension of the building structural components. From that, the planned location of
the beam, column and footings should be easy and convenient to be constructed by
the contractor. In order to ensure the location of structural component is designed
according to the architecture drawings, AutoCAD is employed to draw the pre-layout
by superimposing it from the architecture drawings. Meanwhile, the dimension of the
structural components will be determined, particularly the component’s depth. Then,
the engineer will calculate all the loading that may imposed to the floor by referring
to the standard code of practice. Besides, he/she also needs to visualize how the
loading and forces will be transferred to the structural component, so that the
structural components are supported in most economic and appropriate way.
After all the loadings have been calculated and checked, all the relevant data
will be inputted into the design software, such as the beam and column layout,
loading, dimension, material grade, soil bearing capacity and etc. After that, engineer
will check for any error before the calculation is started. On the other hand, some
structural component that cannot be designed by using the computer software may
need to be designed manually and according to the design clauses. In order to
achieve better, acceptable and adequate design, several trials may be required,
especially the depth and allowable maximum dimension of the beam and slab.
Besides, during this detail design stage, the engineer must ensure that the
reinforcement bar should be easily fabricated, installed and cast.
After the calculation yields the final result, design process will be further to
the next step, which also known as preparation of building key plan. Due to the
design analysis may yield various dimension and detailing, hence some structural
components may need to be standardized. This improves the constructability of the
design and therefore eases of construction. Sequentially, the building key plans will
be submitted back to the client and architect for checking, costing and agree by them.
76
At this stage, changes may happen very often due to changes in client requirements
and initial plan. As a result, rework on certain part of the design will be inevitable.
If the client and architect had agreed to the building key plan, the building
design process will proceed to the preparation of detail drawings and its specification.
According to the interviewee of consultancy firm #C1, some of the detailing and
specification can be retrieved from the previous design drawings, in order to shorten
the drawing preparation time. At this stage, it is civil engineer responsibility to
ensure the dimensions and detailing of all structural components are correct, being
standardized, realistic in term of tolerance among the reinforcement bar and
connection, and detail and clear design information and specification. Then, the
professional engineer will be the last person to check all the designs prior to stamp
and put down his signature. Eventually, those detailed drawings and specification
will be submitted to the client for procurement stage.
The interviewee in consultancy firm #C1 suggested that the preliminary
design stage in engineering design work begins immediately after receiving the
architecture drawings until the pre-layout plans of the building structure are sketched.
While the detailed design starts from calculating all the loading and forces for design
analysis until the completion of detailed drawings and specification.
4.3.1.1 Model of Consultancy Firm #C1
Based on the above information provided by the interviewee from the
consultancy firm #C1, the current design process model of consultancy firm #C1 is
shown in Figure 4.2a, 4.2b and 4.2c. Generally, the preliminary design process of
this case study consists of drawing study and calculation of forces and loading.
Meanwhile, the detailed design process of this consultancy firm #C1 consists of
structural design analysis, key plan preparation and produce detail drawings and
specification. Besides, Figure 4.2b and Figure 4.2c illustrated the entities of
consultancy firm #C1 model are the client, architect and British Standard code.
77
Preliminary Design Process
1.1
Drawing
Study
Clauses
Standard Loading
SI Report
Architectural
Drawings
Pre-layout
Plan
1.2
Forces &
Loading
Calculation
Pre-layout
Plan with
Loads
2.1
Design
Analysis
Client
Requirements
Engineering
Design Result
2.2
Detailing
& Specs
Standard Details
& Specification
2.3
Order
Produce Detail
Drwg & Specs
Retrieve
Approved
Key Plan
Engineering
Drwgs & Spec
Key Plan
Preparation
Key Plan
Approved
Key Plan
Comments &
Approval
Drawings
Detailed Design Process
Figure 4.2a
The current building design process mode l#C1: level 2, preliminary
design and detail design
Architectural
Drawings
Architect
Comments &
Approval
Key Plan
British
Standard
Standard
Loading
2
1
Preliminary
Design
Pre-layout Plan
with Loads
Detailed
Design
Clauses
British
Standard
Key Plan
SI Report
Comments
& Approval
Client
Requirements
Engineering
Drwgs & Spec
Client
Figure 4.2b : The current building design process model #C1: level 1
78
Architect
Architectural
Drawings
Standard
Loading
Key Plan
Comments &
Approval
0
Current
Building Design
Process #C1
British
Standard
Clauses
Client
Requirements
SI
Report
Key
Plan
Comments
& Approval
Engineering
Drwgs & Spec
Client
Figure 4.2c
The context diagram of current building design process model #C1:
level 0
4.3.1.2 Additional Information from Consultancy Firm #C1
This section describes the opinions and suggestions of the interviewee of the
consultancy firm #C1 to the questions number 3 to 6.
According to the interviewee of consultancy firm #C1, consideration of
constructability and its input should be injected in the beginning of the engineering
design work, such as during the drawing study. It is because it is the best for engineer
to know and understand what features that need to be given more attention during the
design. From that, the chances of producing unsuitable design or not ideal decision
making is minimize, and therefore rework of the design will able be minimized too.
In other words, the time of injection of the constructability inputs should promote
and enhance design correctly in first time. In addition, the appropriate time to review
the design constructability suggested to be before the design or its framework is
going to be finalized and agreed by the client.
Regarding to the question number 5, the interviewee responded that if the
engineers do not have enough experience in certain kind of design, they need to be
guided and their works need to be checked by the more experience engineer.
However, the engineer who produces the designs, should always ensure and check its
79
correctness, considered all the design consequences and ensure the designs can be
constructed on site, before their designs are checked by the professional engineer.
The interviewee of the consultancy firm #C1 chose nine constructability
principals that can be used and reviewed in foundation design works. They are:
•
Principle P1: Carry out through investigation of the site
•
Principle P2: Design for minimum time below ground
•
Principle P4: Encourage standardisation/repetition
•
Principle P8: Investigate any unsuspected unrealistic of incompatible
tolerance
•
Principle P12: Investigate the impact of design on safety during
construction
•
Principle P14: Design for skills available
•
Principle P15: Consider suitability of design materials
•
Principle P16: provide detail and clear design information
•
Principle P18: Consider adverse weather effect in selecting materials or
construction method
4.3.2
The Consultancy Firm #C2
From the information gained from consultancy firm #C2, site survey and
authorities requirements are the inputs for architect to produce the architecture’s
schematic plan. Normally, the schematic plan presented the client-desire architectural
building, types of building, layout and size, which according to its purpose and
function of the building. Based on the schematic plan prepared by the architect,
architect, civil engineers and M&E engineers will involved in several discussions.
During the discussion, structural engineers will determine types of the structural
system that need to be adopted, such as composite structural system, prefabricated
component in certain area instead of cast in-situ and types of footing, in terms of
cost-effectiveness, early completion, safety, buildability and etc. Hence, the soil
80
investigation report is inserted at here. As a result, architecture drawings will be
developed from the discussion and it lets the client know whether his/her
requirements are fulfilled or whether the designers understood what the client exactly
desired. Then, quantity surveyor will cost out the overall budget of the building
based on that architecture drawings. Several changes may be carried out too in order
to suit the client requirement.
If the initial costing is under the client budget and client agreed on that
preliminary plan, the design process will proceed to engineer for detail engineering
design. Sometimes, the civil engineer who participated to the discussion mentioned
above may not directly do the building design work. They may assign it to his/her
subordinators, such as the junior engineer. Therefore, it is a common practice that the
civil engineer requires to study those architecture drawings plan prior commence of
the following design work. In addition, civil engineer also needs to bear in mind that
his/her design are not only comfort to the architecture drawings, but also client
requirement too, particularly the cost and material quantities. Besides, civil engineer
also needs to identify any structure, which requires specific or special dealing and
design, such as connection between the prefabricated component and the cast in-situ
concrete.
Then, civil engineer will determine and sketch out the location of beam,
column, wall and footings by superimposing them from the architectural drawings.
During this stage, civil engineer needs to make sure the structural building is not
“over-putting” with beam, column, trusses and footing, where they quantities have a
significant affect over the cost of construction and constructor’s work load. Hence,
proper supervision is required, particularly to the junior engineer and the engineer
who is in first time to design such building. From that, the potentially of producing
poor design can be controlled and early correction can be undertaken before it gives
a deep impact on cost and time of rework at the mid of the design. Subsequently, by
referring to the standard code of practice, civil engineer will calculate all loading and
forces that impose to the building. Besides, he/she also needs to visualize how the
loading and forces will be transferred to the structural component, so that the
structural components are designed and supported in most economic and appropriate
81
way. Based on the loading calculated and his/her experience, engineer will predetermine the dimensions of the structural component, except the architect fixes
them.
After all the loadings have been calculated and their dimension have been
determined, all the data will be inputted into the design software, such as the beam
and column layout, loading, dimension, material grade, soil bearing capacity and etc.
It is encouraged that civil engineer to check for any error before the design analysis
is start. On the other hand, some structural component that can not be designed by
using the computer software is required to be designed manually and according to the
design clauses. In order to achieve better, acceptable and adequate design, several
trials may be required, especially the depth and allowable maximum dimension of
the beam and slab. Besides, during this detail design stage, the engineer also must
ensure that the reinforcement bar should be easily fabricated, installed and cast,
instead of congested and complex.
After several tries of design analysis had yielded the final outcome, the key
plans of the building will be prepared. These building key plans are need to be
checked by the architect and agreed by client. Sometimes, changes to the building
design may occur due to the client decision. As a result, rework on certain part of the
design will be inevitable. Because of the design analysis always yield various
dimension and detailing, hence some structural components may need to be
standardized and renumbered, subject to its necessary. Therefore, the designs are
considered its constructability in the means of standardization.
According to the interviewee of consultancy firm #C2, detail drawings and its
specification only will be prepared after the architect and client had agreed to the key
plan, in order to avoid unnecessary of wastage caused by client if changes occur. As
like other consultancy firms, some of the detailing and specification will be retrieved
from the previous design drawing, and therefore it will shorten the drawing
preparation time. At this stage, all structural components are required to be check for
being standardized, realistic in terms of tolerance among the reinforcement bar and
connection, and detail and clear design information and specification, particularly for
82
the steel structure. Then, as usual, professional engineer will be the last person to
check all the designs prior to stamp and put down his signature. Eventually, those
detailed drawings and specification will be submitted to the client for procurement
stage.
In this case study, the interviewee in consultancy firm #C2 categorized that
the preliminary design stage should immediately begin from the architects prepare
their preliminary plan until the architecture’s schematic drawings are developed
from that several discussion among the architect and engineers. On the other hand,
the detailed design starts from the design calculation until the completion and
printing out of detailed drawings and specification.
4.3.2.1 Model of Consultancy Firm #C2
Based on the above information provided by the interviewee from the
consultancy firm #C2, the current design process model for consultancy firm #C2 is
shown in Figure 4.3a, 4.3b and 4.3c. Generally, the preliminary design process of
this case study consists of produce schematic plan, discussion, estimating costs,
drawing study and calculation of forces and loading. Meanwhile, the detailed design
process of this consultancy firm #C2 consists of structural design analysis, key plan
preparation and produce detail drawings and specification. The standard details and
specification serve as the storage database for the produce detail drawing and
specification process. While, the drawing serves as the storage database for both
preliminary and detailed design processes. Therefore, Figure 4.3b and Figure 4.3c
illustrated the entities of consultancy firm #C2 model are the authorities,
topographical information, client, architect and code of standard.
83
Preliminary Design Process
Authorities
Requirements
Site Survey
SI Report
1.1
Plan
Arch.
Discussion
Comments &
Feedback
Drawings
Arch.
Drwgs
Retrieve
Arch. Drwgs
Estimating
Costs
Drwgs
Arch.
Drwgs
Client
Requirements
Estimated
Cost
1.3
1.2
Schematic
Produce
Schematic
Plan
Arch.
Drwgs
Preliminary
Plan
Notification
Clauses
1.5
1.4
Drawing
Study
SI Report
Pre-layout
Plan
Forces &
Loading
Calculation
Pre-layout
Plan with
Loads
Standard Loading
2.2
Detailing
& Specs
Standard Details
& Specification
2.3
Approved
Produce Detail
Drwg & Specs
Key Plan
Engineering
Drwgs & Spec
Figure 4.3a
Design
Analysis
Engineering
Design Result
Key Plan
Preparation
Key Plan
Retrieve
Detailed Design Process
2.1
Comments &
Approval
Drawings
The current building design process model #C2: level 2, preliminary
design and detail design
84
Topographical
Info
Architect
Site Survey
SI
Report
Authorities
Authorities
Requirements
Engineering
Drwgs &
Spec
Drawings
Arch.
Drwgs
Retrieve
Arch. Drwgs
1
Comments
& Approval
2
Pre-layout
Preliminary
Design
Key
Plan
Detailed
Design
Plan with Loads
Standard Loading
Estimated
Cost
Schematic
Plan
Code of
Standard
Comments &
Feedback
Clauses
Code of
Standard
Key
Plan
Comments
& Approval
Client
Requirements
Client
Engineering
Drwgs & Spec
Figure 4.3b : The current building design process model #C2: level 1
Topographical
Info
SI
Report
Site Survey
Authorities
Authorities
Requirements
Client
Requirements
Figure 4.3c
level 0
Architect
Comments
& Approval
0
Current
Building Design
Process #C2
Schematic Estimated
Cost Comments &
Plan
Feedback
Key Plan
Key
Plan
Standard
Loading
Clauses
Comments
& Approval
Code of
Standard
Engineering
Drwgs & Spec
Client
The context diagram of current building design process model #C2:
85
4.3.2.2 Additional Information from Consultancy Firm #C2
According to the interviewee of consultancy firm #C2, consideration of
constructability and its input should be injected in the beginning of the engineering
design and its detail design stage. It is because it is the appropriate time where
engineers are starting to consider all the circumstances that may affect the decision
making and design result. Referring to the question number four in Appendix A, the
interviewee responded that it is not encourage to has the constructability review
process in the design, due to the simplicity of small and medium size project. It s
because the interviewee commented those small building’s design works are very
straightforward and common sense to design a building in first time correct.
However, unless the project is very complex, huge and long construction duration,
the design constructability review process should be carried out during the early
stage of the design.
Regarding to the question number 5, the interviewee of consultancy firm #C2
responded that it is the engineer duty and responsibility to do, consider all
requirement and circumstances, and check it works correctly before present those
design or drawings to the senior engineer. However, an in-house checking, where the
engineers works will be guided and checked by the professional or experience
engineers. Hence, a good consultancy firm is normally being in charged by at least
one senior engineer who had gained many years of experience in design and indeed
knowledgeable in engineering design.
The interviewee of the consultancy firm #C2 also chose nine constructability
principals that can be used and reviewed in the foundation design works. They are:
•
Principle P1: Carry out through investigation of the site
•
Principle P2: Design for minimum time below ground
•
Principle P4: Encourage standardisation/repetition
•
Principle P8: Investigate any unsuspected unrealistic of incompatible
tolerance
86
•
Principle P11: Consider storage requirement at the jobsite
•
Principle P12: Investigate the impact of design on safety during
construction
•
Principle P15: Consider suitability of design materials
•
Principle P16: provide detail and clear design information
•
Principle P18: Consider adverse weather effect in selecting materials or
construction method
Based on the experience of the interviewee, he had shared several examples
about some important features that need to be considered and determined before and
during the building foundation design. They are:
a)
Adequacy of site information, such as conduct a site visit, availability
of clear and adequate information in topographical map and survey
plan.
b)
Adequacy of soil investigation, particularly the location and numbers
of Mackintosh Probe Test and Borehole should be appropriate and
adequate, where they must truly reflected the soil condition,
characteristic, and sub-soil strata.
c)
Determine the existence of any underground services, where it can
affect the location of the building foundation and column.
d)
For any building project that surrounded by other adjacent building or
the area is need to maintain its tranquillity, the engineers needs to
select suitable foundation and appropriate construction method in
order to comply the environment, health, safety and other authorities
requirements.
e)
Minimal variation or standardization of foundation and stump size and
depth. Besides, avoid any odd dimension that can cause extra
workload during the construction.
87
4.3.3
The Consultancy Firm #C3
From the interview with consultancy firm #C3, preliminary design process of
a building project is starts when architect produces the architectural preliminary
drawing which based on the some important information, such as the client
requirements, the building cost plan, and topography of the site and its environment.
Normally, client will comment the first architectural preliminary drawing. Those
comments will be feedback to the architect and produce another architectural
preliminary drawing, until the client is satisfied. Then, architect will work out the
architectural schematic drawing based on the architectural preliminary drawing that
had been agreed by the client. These architectural schematic drawings present a more
detail of building and space dimension, elevation, location of each facilities and etc.
Besides, they should be fulfilled with local authorities’ requirements. From those
drawings, civil engineer will work out the engineering preliminary plan which
according to the client requirements, site condition and soil investigation report.
Based on the purpose and function of the building, an experience engineer can
estimate the dimension of the structural components. Therefore, several alternatives
of engineering design will be proposed, if the designs can not economically be
constructed by conventional method or according to what the client wanted. Hence,
discussion among the architect, civil engineers, M&E engineer and client is essential,
where all the project team members can discuss types of the structural system that
need to be adopt, building cost and constructability issue. From the discussion,
several of feedbacks may send to the architect or engineers to produce another
drawing that fulfilled with the client or architect requirements for next discussion.
Then, quantity surveyor will cost out the overall budget of the building based on that
architecture drawings and engineering preliminary plan. Commonly, client will
comment on those drawings again if the cost feedback shows the cost of building is
over the budgeted cost.
After all the architectural schematic drawings and engineering preliminary
plan had been agreed and approved by the client, the design process will proceed to
the detail design stage. The architect will complete all his/her drawing by producing
the detail architectural drawing. All the detail architecture information and
88
specification, such as the material and specifications for each component, location
and dimension of each utilities, finishes’ quality and etc, will be presented in that
drawing. Meanwhile, the civil engineer will begin his/her engineering design and
analysis. Sometimes, the civil engineer who participated to the discussion mentioned
above may not directly do the building design work. They also may assign it to
his/her subordinators, such as the junior engineer. Therefore, a thorough of drawing
study is essential prior commence of the following design process. Within the detail
engineering design and analysis process, civil engineer will calculate all the loading
and forces again, and then design it according to standard code of practice by using
computer software or manually.
After several tries of design and the analysis had yielded the final outcome,
civil engineer or draftsman will produce the building structural layout plans. These
structural layout plans indicated the exact dimension and cross section of each
structural component. Meanwhile, some structural components are required to be
standardized and renumbered, subject to its necessary, due to the design analysis
always yield various dimension and detailing. After that, the structural layout will be
checked by the architect and agreed by client. Sometimes, minor changes to the
building design may occur due to the client request. As a result, rework on certain
part of the design will be inevitable.
After the client had approved the structural layout, the design work will be
finalized by producing a complete set of detail drawings and its specification. As like
other consultancy firms too, some of the detailing and specification are retrieved or
modified from the previous design drawing in order to reduce the workload and
shorten the preparation time. Last but not less, senior engineer or professional
engineer will check all the drawing thoroughly before the endorsement and
submission to the client.
89
4.3.3.1 Model of Consultancy Firm #C3
Based on the above information provided by the interviewee from the
consultancy firm #C3, the current design process model for consultancy firm #C3 is
shown in Figure 4.4a, 4.4b and 4.4c. The preliminary design process of this case
study consists of several processes, which they are produce architectural preliminary
drawing process, produce architectural schematic drawing process, produce
preliminary plan process, discussion process, and estimating cost process. Besides,
the detailed design process consists of produce detail architectural drawing, detail
engineering design process produce structural layout process and produce detail
engineering drawing process. The prices and standard details and specification
served as the storage database for the estimating costs process and produce detail
engineering drawing process, respectively. While, the drawing serves as the storage
database for both preliminary and detailed design processes. Therefore, Figure 4.4b
and Figure 4.4c illustrated the entities of consultancy firm #C3 model are the
authorities, topographical information, client, architect and code of standard.
90
Preliminary Design
Process
Prices
1.5
Prices
Estimating
Costs
Request
Client
Requirements
Authorities
Requirements
Site
Survey
1.1
Arch.
Preliminary
Design
Cost
Plan
Arch. Drwg. + Eng.
Preliminary Plan
Arch. Schematic
Drwg.
1.2
Arch.
Preliminary
Arch.
Schematic
Design
Drwg.
1.4
Comments &
Feedback
Discussion
Feedbacks
Arch.
Schematic
Drwg.
Arch.
Preliminary
Drwg.
Cost
Feedback
Eng.
Preliminary
plan
Feedbacks
Client
Requirements
Standard
Loading
Comments
1.3
Retrieve
Drawings
Arch. Schematic
Drwg.
Produce Eng.
Preliminary
Plan
App.
Preliminary
Design Doc.
Site Survey
SI Report
2.1
Detail Arch. Drwg.
Engineering
Drwgs & Spec
Detail Arch
Design
Arch. Drwg.
Notification
2.3
2.4
Produce Detail
Eng. Drwg.
Retrieve
Approved
Structural
Layout
Produce
Structural
Layout
Detailing
& Specs
Comments &
Approval
Standard Details
& Specification
Figure 4.4a
2.2
Engineering
Design Result
Detail Eng.
Design
Clauses
Structural Layout
Detailed Design Process
The current building design process model #C3: level 2, preliminary
design and detail design
91
Topographical
Info
Site Survey
SI
Report
Authorities
Engineering
Drwgs &
Spec
Drawings
Detail
Arch.
Drwg.
Arch.
Schematic
Drwg.
Architect
Structural
Layout
Arch.
Drwg.
Retrieve
Authorities
Requirements
1
App. Preliminary
Preliminary
Design
Standard
Loading
Detailed
Design
Design Doc.
Standard
Code of
Practice
Comments
& Approval
2
Standard
Code of
Practice
Clauses
Comments &
Feedback
Cost
Feedback
Comments
Structural
Layout
Arch.
Preliminary
Drwg.
Cost
Plan
Comments
& Approval
Client
Requirements
Engineering
Drwgs & Spec
Client
Figure 4.4b : The current building design process model #C3: level 1
Topographical
Info
Site Survey
Architect
Structural
Layout
SI
Report
Authorities
Comments
& Approval
Authorities
Requirements
Cost
Plan
Client
Requirements
0
Clauses
Current
Building Design
Process #C3
Standard Loading
Comments
Cost
Feedback
Comments
&
Feedback
Standard
Code of
Practice
Structural
Layout
Comments
& Approval
Client
Engineering
Drwgs & Spec
Figure 4.4c
level 0
The context diagram of current building design process model #C3:
92
4.3.3.2 Additional Information from Consultancy Firm #C3
According to the interviewee of consultancy firm #C3, consideration of
constructability and its input should be injected as early as possible of the design,
particularly before produce any design drawings for discussion among the client and
designers. It is because wastage of resources will happen if any features, which must
be considered at the beginning of the design, are overlooked and yet only be
discovered at the end of the design. Hence, a consultancy firm which also a profit
based company, needs to avoid such circumstance. The interviewee responded the
question number four in Appendix A that if constructability is needed to be proposed
in the design process, the review should be conducted in the early stage of the design.
It is because any reviews and changes are should be settled down in the early stage of
the design, where the design decision has not been finalized and agreed by the client.
However, review of the design constructability also can be carried out for certain
features during the detail design stage, where the reviewed result will not change the
fixed design framework and therefore does not increase project cost.
Regarding to the question number 5, the interviewee of consultancy firm #C3
also responded that engineers who also as the employee of a business based company
are responsible to do his duty, consider all requirement and circumstances, design
and check his works are correct, particularly before present any design or drawings
to the senior engineer and client. Nonetheless, the senior engineer will given
adequate guidance to the young and inexperience engineer, where their works are
checked by the professional or experience engineers.
The interviewee of the consultancy firm #C3 selected ten constructability
principals that suitable to be used for inputting and reviewing the foundation design.
They are:
•
Principle P1: Carry out through investigation of the site
•
Principle P2: Design for minimum time below ground
•
Principle P4: Encourage standardisation/repetition
93
•
Principle P8: Investigate any unsuspected unrealistic of incompatible
tolerance
•
Principle P11: Consider storage requirement at the jobsite
•
Principle P12: Investigate the impact of design on safety during
Construction
•
Principle P14: Design for skills available
•
Principle P15: Consider suitability of design materials
•
Principle P16: provide detail and clear design information
•
Principle P18: Consider adverse weather effect in selecting materials or
construction method
Based on the experience of the interviewee, several features that need to be
considered and checked for the building foundation design were shared at the end of
the interview session. Among them are:
a)
Adequacies of site survey and soil investigation information are the
most important features that need to be carried out before proposing
any foundation system. For example, type of ground formation in
terms of cut and fill involved, conducting the inspection of adjoining
areas and site exploration when it is required, using appropriate soil
investigation method, and site accessibility.
b)
Suitability of the selected foundation system with site constraints and
accessibility of necessary equipments.
c)
Method of construction that comply with the environmental, health,
safety and other statutory requirements.
d)
Odd dimensions of the footing and standardize it according to the
company standard details are avoided.
e)
The designs comply with standard code of practice.
f)
All dimensions, detailing information, notes and specification are
clear, concise and complete.
94
4.4
Summary
Based on the responses of the interviewees to the interview questions, the
summaries of this chapter are shown in Table 4.1 and Table 4.2.
Table 4.1 : The summary of the interviewee #A1 and #C1’s responses
Architect Firm #A1
Consultancy Firm #C1
Preliminary design process includes:
- produce architectural sketches
- produce architectural schematic
Q1
design
- discussion
Preliminary design process includes:
- drawing study
- forces and loading calculation
Detail design process consists of:
- produce detail architectural
design
Q2
- produce construction drawing
by consultant
Detail design process consists of:
- design analysis
- key plan preparation
- produce detail drawings and
specifications
When architect starts sketching the When the engineer starts his/her
design
during
the design work, such as during the
Q3 concept
architectural preliminary design.
drawing study.
Recommended to be reviewed for its Should not wait until the design or
Q4 constructability before meeting the its framework is going to be
client and consultants.
finalized and agreed by the client.
Other than just fulfilling the client
requirements, the architect himself
should ensure the design is
Q5 construct-able and free of omission.
However, senior architect will guide
and check the fresh architect’s
design work.
Q6
P1, P15, P16, P18
If the engineers do not have enough
experience in it, they will be guided
and their works will be checked by
the more experience engineer.
P1, P2, P4, P8, P12, P14, P15, P16,
P18.
95
Table 4.2 : The summary of the interviewee #C2 and #C3’s responses
Q1
Consultancy Firm #C2
Consultancy Firm #C3
Preliminary design process includes:
Preliminary design process includes:
- produce schematic plan
- architectural preliminary design
- discussion
- architectural schematic design
- estimating costs
- engineering preliminary plan
- drawing study
- discussion
- forces and loading calculation
- estimating costs
Detail design process consists of:
Q2
Detail design process consists of:
- design analysis
- detail architectural design
- key plan preparation
- detail engineering design
- produce detail drawings and
- produce structural layout
specifications
- detail engineering drawing
In the beginning of the project design It should be injected as early as
Q3 and its detail design stage.
possible in the design, particularly
before the discussion.
Due to the simplicity of small and Should be conducted in the early
medium size project, it is not stage of the design, where the design
encouraged to conduct the construct- decision has not been finalized and
ability review process (CRP) in that agreed by the client. Certain features
Q4
design, because it is very straight can be reviewed during the detail
forward for engineer to design it design stage, where the reviewed
correctly in the first time. Unless, the features will not change the fixed
project is very complex, CRP should design framework and therefore does
be carried out during the early stage not increase project cost.
of the design.
It is the engineer duty and responsibility to do, consider all requirements and
Q5
circumstances that may affect his/her design, and check it correctly.
However, their work also will be guided and checked by the professional
engineer.
Q6
P1, P2, P4, P8, P11, P12, P15, P16, P1, P2, P4, P8, P11, P12, P14, P15,
P18
P16, P18
96
CHAPTER 5
MODEL DEVELOPMENT AND DISCUSSION
5.1
Introduction
This chapter presents the development and discussion of the general design
process model which based on the four case studies’ model, and constructability
integrated building design process, that integrated with a review design
constructability process and constructability checklists as an entity. However, the
development of constructability checklist is discussed in chapter 6.
5.2
The General Building Design Process Model
After series of reviewing and refining with the pre-appointed experts through
discussions, a general building design process was developed by comparing,
combining and generalizing among the four current building design process models
in Chapter 4. Figure 5.1 shows the context diagram for the general building process
consists of five entities: topographical information, authorities, client, architect, and
standard code of practice.
Figure 5.2 is the top-downed view to the general building process, where it
consists of preliminary design process, estimating costs process and detailed design
process. A data store named drawings function as a storage place for all architectural
97
and engineering drawings that can be retrieved by architect, quantity surveyor and
engineers. While, the prices is a data store, where quantity surveyor can retrieve the
market prices for estimating building cost.
Topographical
Info
Authorities
Site
Information
Authorities
Requirements
Standard Loading
Standard Code of
Practice
Clauses
Cost
Plan
Comments
Sketches
Structural
Layout
0
General
Building Design
Process
Structural
Layout
SI
Report
Comments &
Approval
Budget
Comments
& Approval
Client
Requirements
Architect
Estimated
Cost
Cost
Feedback
Construction
Drawings
Client
Figure 5.1 : The context diagram of general building design process model: level 0
98
Client
Budget
Estimated
Cost
Cost
Feedback
Topographical
Info
Prices
2
Estimating
Costs
Arch. Drwg.
+ Eng.
Preliminary
Plan
Arch. + Eng.
Drawings
SI
Report
Site
Information
Prices
Request
Drawings
Authorities
Authorities
Requirements
Standard Code of
Practice
Arch.
Schematic
Drwg.
Detail
Arch. Drwg.
Comments &
Approval
3
1
App. Preliminary
Preliminary
Design
Standard
Loading
Architect
Structural
Layout
Arch.
Drwg.
Retrieve
Arch. Schematic
Drwg.
Eng. Drawings
& Spec.
Detailed
Design
Design Doc.
Clauses
Structural
Layout
Comments
Standard Code of
Practice
Comments &
Approval
Cost
Client
Plan
Requirements
Construction
Drawings
Sketches
Client
98
Figure 5.2 : The general building design process model: level 1
99
Figure 5.3 is the level 2 for preliminary design process, where it consists of 4
sub-processes; they are produce architectural preliminary design process, produce
architectural schematic design process, produce engineering preliminary plan process,
and discussion process. Generally, client meets the architect and describes in detail
about his/her requirements and cost plan of the building. Then, the architect will
gather site information by conducting site survey. Based on the client requirements,
cost plan and site information, the architect works out his first building sketches
during the produce of architectural preliminary design stage. Meanwhile, the
architect will refer the materials information and retrieve some idea form the
architectural references, in order to sketch out a better building architectural design
asked by the client. After than, those sketches will be reviewed and comments by the
clients.
Site
Information
Cost Plan
Authorities
Requirements
Client
Requirements
Materials
Arch. Schematic
Drwg.
Materials
1.1
Produce Arch.
Preliminary
Design
App. Arch.
Preliminary
Drwg.
1.2
Produce Arch.
Schematic
Design
Refer
Idea
Arch. Schematic
Drwg.
Comments
Sketches
Architectural
References
Feedbacks
Client
Requirements
1.3
Standard
Loading
Eng. Preliminary
Plan
Produce Eng.
Preliminary
Plan
Site
Information
Retrieve
Discussion
Feedbacks
App.
Preliminary
Design Doc.
SI Report
Arch. Schematic
Drwg.
1.4
Arch. Drwg. +
Eng. Preliminary
Plan
Comments
Cost
Feedback
Figure 5.3 : The general building design process model: level 2, preliminary design
100
After receiving the approved architectural preliminary plan, the architect will
produce their architectural schematic design. The architectural schematic drawings
will be sent to the consultant engineers for producing their engineering preliminary
plans that are needed for the following discussion stage. Hence, the required inputs to
produce those plans are the client requirements, site information and soil
investigation report that contribute by the topographical information entities,
standard loading from standard code of practice, and the architectural schematic
drawings retrieved from the drawings data store.
Then, based on the architectural schematic drawings and engineering
preliminary plans, discussion will be conducted among the client and all designers.
The purpose of the discussion is to determine and select the design, such as types of
the structural system that need to be adopted, materials grade and its quality,
alternative design and etc. Besides, client will let the quantity surveyor to estimate
the rough construction cost, based on the architectural drawings and engineering
preliminary plans that purposed by the architect and engineers. Hence, client may
give several comments and cost feedback. Design changes may happen if the client is
not satisfied with the design or costing result. Therefore, the architect and engineers
will amend their design according to the feedbacks. As a result, several discussions
are required before the preliminary design process proceed to the detail design
process stage.
Figure 5.4 illustrated the detailed design process, where it comprises of 4 subprocesses, such as produce detail architectural drawing process, detail engineering
design process, produce structural layout process, and produce detail engineering
drawing process. After the general design framework has been determined and
selected during the discussion, the architect will produce their detail architectural
drawings. The inputs of this process are approved preliminary design document and
architectural schematic drawings that can be retrieved from the drawings data store.
After that, the architect sends a notification to the engineers.
101
App.
Preliminary
Design Doc.
Arch. Schematic
Drwg.
App.
Preliminary
Design Doc.
3.1
Detail Arch.
Drwg.
Arch. Drwg.
3.2
Produce Detail
Arch Drwg.
Notification
Engineering
Drwgs & Spec
Engineering
Design Result
3.3
3.4
Construction
Drawings
Clauses
Detail Eng.
Design
Produce Detail
Eng. Drwg.
Retrieve
Detailing
& Spec.
Approved
Produce
Structural
Layout
Structural
Layout
Comments &
Approval
Structural Layout
Standard Details
& Specification
Figure 5.4 : The general building design process model: level 2, detailed design
Meanwhile, the engineers may begin their detail engineering design, such as
study the architectural drawings, calculate the actual loading and forces, and run the
design analysis. Hence, the inputs for the detail engineering design process are
approved preliminary design document, all architectural drawings that retrieved form
the drawings data store, and clauses from the standard code of practice. The outcome
of the detail engineering design is engineering design result. From that, the engineers
or their draftsmen will sort up the results and produce a standard structural layout.
Then, the structural layouts are needed to be checked by the architect for drawing
coordination, and submitted to the client for comments and approval. Hence, the
engineers are required to produce good design in order to fulfil the client
requirements, i.e. can be constructed within the budget, and therefore minimize the
design reworks.
After the structural layout have been commented and approved by the client
and architect, engineers will produce detail engineering drawings, where all
specification will be described in detail and concise. Normally, the engineers will
102
retrieve the standard detailing and specification from their company’s standard
details and specification data store. In contrast, they need to produce those detailing
and specification if it can not be found from the data store. After that, those drawings
will be saved and client will request the quantity surveyor for detail costing. If the
estimated cost is more than the budgeted cost or the client made a sudden change to
the design, his/her requirements or budget, then the design may either needs to be
redesigned either from the discussion process or detail engineering design, which it
depends on the degree of the changes. Finally, the construction drawings will be
produced if there are no further changes to the design and accepted by the client.
Table 5.1a , Table 5.1b, Table 5.2a, Table 5.2b and Table 5.3 summarized all
the inputs and outputs of the processes that involved in the general building design
process model.
Table 5.1a : Inputs and outputs of process 1: preliminary design
Processes
Inputs (from)
Outputs (to)
Client Requirements (Client)
Cost Plan (Client)
Process 1.1:
Produce
Architectural
Preliminary
Design
Refer
(Architectural References)
Site Information
(Topographical Information)
Materials (Materials)
Idea (Architectural References)
App. Arch. Preliminary Drwg.
(Process 1.2)
Comments (Client)
Process 1.2:
Produce
Architectural
Schematic
Design
App. Arch. Preliminary Drwg.
(Process 1.1)
Authorities Requirements
(Authorities)
Feedbacks (Discussion)
Comments (Client)
Arch. Schematic Drwg.
(Drawings & Discussion)
103
Table 5.1b : Inputs and outputs of process 1: preliminary design (continue)
Processes
Inputs (from)
Outputs (to)
Client Requirements (Client)
Standard Loading
(Standard Code of Practice)
Process 1.3:
Produce
Preliminary
Engineering
Plan
Retrieve (Drawings)
Site Information
(Topographical Information)
SI Report
(Topographical Information)
Arch. Schematic Drwg.
(Drawings)
Eng. Preliminary Plan
(Process 1.4)
Feedbacks (Process 1.4)
Process 1.4:
Discussion
Arch. Schematic Drwg.
(Process 1.2)
Arch. Drwg. + Eng. Preliminary
Plan (Process 2)
Eng. Preliminary Plan
(Process 1.3)
Feedbacks (Process 1.2 & 1.3)
Cost Feedback (Client)
Comments (Client)
App. Preliminary Design Doc.
(Process 3.1 & 3.2)
Table 5.2a : Inputs and outputs of process 3: detailed design
Processes
Inputs (from)
Outputs (to)
Process 3.1:
Produce detail
architectural
drawing
App. Preliminary Design Doc.
(Process 1.4)
Detail Arch. Drwg. (Drawings)
Arch. Schematic Drwg.
(Drawings)
Notification (Process 3.2)
App. Preliminary Design Doc.
(Process 1.4)
Process 3.2:
Detail
engineering
design
Notification (Process 3.1)
Arch. Drwg. (Drawings)
Clauses
(Standard Code of Practice)
Engineering Design Result
(Process 3.3)
104
Table 5.2b : Inputs and outputs of process 3: detailed design (continue)
Processes
Inputs (from)
Outputs (to)
Process 3.3:
Produce
structural
layout
Engineering Design Result
(Process 3.2)
Structural Layout
(Client & Architect)
Comments & Approval
(Client & Architect)
Approved Structural Layout
(Process 3.4)
Approved Structural Layout
(Process 3.3)
Retrieve
(Standard Details &
Specification)
Process 3.4:
Produce detail
engineering
drawing
Detailing & Spec.
(Standard Details &
Specification)
Engineering Drwgs. & Spec.
(Drawings)
Construction Drawings (Client)
Table 5.3 : Inputs and outputs of process 2: estimating costs
Processes
Inputs (from)
Outputs (to)
Budget (Client)
Arch. Drwg. + Eng.
Process 2:
Request (Prices)
Preliminary Plan (Process 1.4)
Estimating
Costs
Prices (Prices)
Arch. + Eng. Drawings
(Drawings)
Estimated Cost (Client)
105
5.3
The Constructability Integrated Building Design Process Model
Based on the suggestion of the interviewees in Chapter 4 and general building
design process model discussed above, a constructability integrated building design
process model was developed. After series of reviewing and refining from the preappointed experts through discussions, an entity, named constructability checklists,
are proposed in this model, where it contributes the constructability inputs and
checklists to the design processes. Figure 5.5 illustrated the context diagram of
constructability integrated building design process model of this study.
Constructability
Checklists
Constructability
Inputs
SI
Report
Authorities
Site
Information
Authorities
Requirements
Clauses
Cost
Plan
Amended
Structural Layout
0
Standard Loading
Standard Code
of Practice
Topographical
Info
Checklists
Constructability
Integrated
Building Design
Process
Amended
Comments Structural
Sketches
Layout
Architect
Comments &
Approval
Budget
Comments
& Approval
Client
Requirements
Estimated
Cost
Cost
Feedback
Construction
Drawings
Client
Figure 5.5
The context diagram of constructability integrated building design
process model: level 0
The beginning of the architect’s design work is producing the architectural
preliminary design. While, the engineers’ design work only will starts after the
architect had produced their architectural schematic design. Therefore, it is proposed
106
that the constructability elements be viewed and considered during the early stage of
both processes, as in Figure 5.6. It is because early understanding of the
constructability elements that need to be considered during both processes can give a
great and significant influence of producing better design. It is rather already late to
know what the constructability features need to be considered after the building is
designed. It is also proposed that designers make use the constructability checklists
as the constructability inputs, where they can study thoroughly the checklists. From
that, it lets them know what constructability features that need to be considered
during the design. Hence, constructability is proposed to be integrated into the
general building design process model by inserting the constructability inputs to the
produce architectural preliminary design process and produce engineering
preliminary plan, in the preliminary design process.
Site
Information
Cost Plan
Authorities
Requirements
Client
Requirements
Materials
Arch. Schematic
Drwg.
Materials
1.1
Constructability
Inputs
Produce Arch.
Preliminary
Design
App. Arch.
Preliminary
Drwg.
1.2
Reviewed Design
Constructability
List
Produce Arch.
Schematic
Design
Refer
Idea
Sketches
Architectural
References
Client
Requirements
Standard
Loading
1.3
Produce Eng.
Preliminary
Plan
Site
Information
Feedbacks
Constructability
Inputs
SI Report
Amended Eng.
Preliminary Plan
Arch. Schematic
Drwg.
Eng. Preliminary
Plan
1.4
Discussion
Feedbacks
App.
Preliminary
Design Doc.
Retrieve
Figure 5.6
Amended Arch.
Schematic Drwg.
Comments
Reviewed Design
Constructability
List
Arch. Drwg. +
Eng. Preliminary
Plan
Comments
Cost
Feedback
The constructability integrated building design process model: level 2,
preliminary design
107
In detail design stage, constructability input also is proposed to be injected in
the detail engineering design process, as in Figure 5.7. It is because the person who
involved in the detail engineering design may not be the same person who involved
in the engineering preliminary plan, due to the company’s working culture. Besides,
the period of conducting the produce engineering preliminary plan process and detail
engineering design process is long. Therefore, the injection of constructability input
by referring back to the constructability checklist can enhance the constructability of
the following detail engineering design. In addition, the features that need to be given
attention for its design constructability during the preliminary design process and
detail design process are different. It is because the design constructability features
that need to be considered and reviewed in the detail design process will not change
the major design framework that had been agreed in the preliminary design stage.
Hence, constructability inputs is proposed to be injected in the beginning of the detail
engineering design, as showed in Figure 5.7, in order to enhance the design
constructability.
App.
Preliminary
Design Doc.
Detail Arch.
Drwg.
Arch. Schematic
Drwg.
App.
Preliminary
Design Doc.
4.1
Comments &
Approval
4.3
Approved
Produce Detail
Eng. Drwg.
Reviewed Design
Constructability
List
Structural
Layout
Retrieve
Detailing
& Spec.
Standard Details
& Specification
Figure 5.7
Engineering
Design Result
4.4
Engineering
Drwgs & Spec.
Clauses
Detail Eng.
Design
Amended Detail
Arch. Drwg.
Construction
Drawings
Amended
Engineering
Drwgs & Spec.
Arch. Drwg.
4.2
Notification
Produce Detail
Arch Drwg.
Reviewed Design
Constructability
List
Constructability
Inputs
Produce
Structural
Layout
Structural
Layout
Amended
Structural
Layout
Reviewed Design
Constructability
List
The constructability integrated building design process model: level 2,
detailed design
108
In level 1 of the general building design process model, a review design
constructability process is also proposed to review and check the design
constructability. In this process, the designers or his/her supervisor can review,
evaluate and analyze the design constructability by using the building design
constructability checklist. Hence, they either will approve or put some remarks in the
checklist according to the features listed in the checklist. Then, a list of reviewed
design constructability will be given to the designers, so that they will amend their
design and drawings if the design is not ok or been given remarks.
As showed in the Figure 5.6, a process of review design constructability is
proposed to be carried out after the produce architectural schematic drawing process
and engineering preliminary plan process. After reviewed its design constructability,
the reviewed design constructability list will be feedback to those processes for
further amendment or proceed to the following stage. In detail design process, the
review design constructability process is proposed to be carried out after produce the
detail architectural drawing process, structural layout and detail engineering drawing,
but before sending any drawings to the drawings data store, client for comments and
approval, and quantity surveyor for cost estimating, as illustrated in Figure 5.7. As
similar in the preliminary design process, the reviewed design constructability list
will be feedback to those processes for further amendment or proceed to the
following stage after it has been review for its design constructability.
Figure 5.8 is the level 1 of the constructability integrated building design
process model, where the integration of constructability into the design process is
proposed to be carried out by having the constructability checklist as a entity that
contribute the constructability inputs and checklists, and a review design
constructability process which denoted as process number 2. As a result, the level 1
of the constructability integrated building design process consists of preliminary
design process, review design constructability process, estimating costs process and
detailed design process. While, the entities and data stores are still remained as in
general building design process model, except the constructability checklists is added
in it. Table 5.4 summarized al the inputs and outputs of the review design
constructability process.
109
Budget
3
Client
Topographical
Info
Site
Information
Estimated
Cost
Arch. Drwg.
+ Eng.
Preliminary
Cost
Plan
Feedback
SI
Report
Authorities
Request
Estimating
Costs
Prices
Prices
Arch. + Eng.
Drawings
Amended Eng.
Drawings & Spec.
Amended Structural
Layout
Drawings
Arch. Drwg.
Authorities
Requirements
Arch. Schematic
Drwg.
Retrieve
Standard Code
of Practice
Standard
Loading
1
Constructability
Checklists
Arch. Schematic
Drwg.
Reviewed Design
Constructability
List
2
Review Design
Constructability
Checklists
Client
Requirements
Cost
Plan
4
Sketches
Comments
Clauses
Detailed
Design
Design Doc.
Eng. Preliminary
Plan
Comments &
Approval
Amended Detail
Arch. Drwg.
App. Preliminary
Preliminary
Design
Constructability
Inputs
Architect
Standard Code
of Practice
Constructability
Inputs
Detail
Arch. Drwg.
Constructability
Checklists
Structural
Layout
Eng. Drawings
& Spec.
Amended
Structural Layout
Comments
& Approval
Construction
Drawings
Client
109
Figure 5.8 : The constructability integrated building design process model: level 1
110
Table 5.4 : Inputs and outputs of process 2: review design constructability process
Processes
Inputs (from)
Outputs (to)
Arch. Schematic Drwg.
(Process 1.2)
Eng. Preliminary Plan
(Process 1.3)
Process 2:
Review Design
Constructability
Reviewed Design
Detail Arch. Drwg.
Constructability List
(Process 4.1)
(Process 1.2, 1.3, 4.1, 4.3 and
4.4)
Structural Layout
(Process 4.3)
Eng. Drawings & Spec.
(Process 4.4)
5.4
Summary
After series of reviewing and refining with the pre-appointed experts through
discussions with them, a general building design process model is developed by
comparing, combining and generalizing among the four case studies’ model. As a
result, the level 1 of general building design process consists of five entities: client,
topographical information, authorities, standard code of practice, and architect; three
processes: preliminary design (process 1), estimating costs (process 2), and detailed
design (process 3); and two data stores: drawings, and prices.
Besides, the level 2 of its preliminary design (process 1) consists of four
processes: produce architectural preliminary design (process 1.1), produce
architectural schematic design (process 1.2), produce preliminary plan (process 1.3),
and discussion (process 1.4); and two data stores: materials, and architectural
references. Whilst, the level 2 of its detailed design (process 3) consists of four
processes: produce detail architectural drawing (process 3.1), detail engineering
111
design (process 3.2), produce structural layout (process 3.3), and produce detail
engineering drawing (process 3.4); one data store named as standard details and
specification.
Based on the general building design process model and the suggestion from
the interviewees, a entity of constructability checklist and a review constructability
process are proposed in the model in order to promote the design constructability by
injecting its inputs, and review and check for its design constructability in the certain
times of the design works. Hence, the numbering of the processes in level 1 of this
new model, named as constructability integrated building design process model, are
rearranged according to the logical of the design workflow. As a result, preliminary
design process is still remained as process 1, review design constructability process
is denoted as process 2, estimating costs process and detailed design process are
renumbered as process 3 and process 4, respectively.
112
CHAPTER 6
CHECKLIST DEVELOPMENT AND DISCUSSION
6.1
Introduction
In the previous chapter, a constructability integrated building design process
model has been developed whereby design constructability is integrated and
enhanced by having a review design constructability process and constructability
checklist. In this chapter, a building design constructability checklist is developed
after it had been undergo series of reviewing and refining with the pre-appointed
experts through discussions. However, the developed checklist is used for building
foundation assessment, due to limitation of time. Design phase’s constructability
principles that being integrated in the features to be checked are also presented.
6.2
The Development of Design Constructability Checklist
Based on the responses from all interviewees, a design constructability
checklist for building foundation assessment is developed. Totally, there are 13 main
features that needs to be checked for its design constructability, are constructed.
They are:
a)
General characteristic of the surrounding;
b)
Types of ground formation;
113
c)
Adequacy of oil investigation information;
d)
Adequacy of Borehole numbers that depends on site condition;
e)
Site exploration, such as geological formation and subsoil strata;
f)
Consideration of site clearance;
g)
Site suitability of selected foundation system;
h)
Consideration of construction and/or testing equipments and tools for
the selected foundation system;
i)
Requirement to the environmental, health, safety and other statutory
compliance for the construction;
j)
Minimize the complexity of foundation design;
k)
Construction material to the selected type of foundation;
l)
Detail design and construction drawings; and
m)
Clear marking and positioning.
Besides, each of the main features are detailed with other sub-features to be
checked, so that it can assist the users to know what things are needed to be
considered before the start of design work and reviewed the design constructability
before completion of the design. Three columns, respectively named as ok, not ok
and remarks, are prepared in the checklist form for assessment purpose. Table 5.1
showed one of the sections in building design constructability checklist, where the
complete checklists are demonstrated in Appendix B.
1.
General characteristic of the surrounding
• Topographical map or landscape
• Existing planting or trees
• Existing or previous building
• Others infrastructure, e.g.: road, water,
electricity, drains and etc
• Survey plan
Not OK
Features to be checked
OK
Items
Table 6.1 : Item no. 1 of the building design constructability checklist
Remarks
114
6.3
The Discussion
The purpose of having this design constructability checklist is to use it as a
tool for promoting, implementing and enhancing the foundation design
constructability. It is because those features stated in the checklist are integrated with
constructability principles that have been discussed in Chapter 2. In other words, the
designers will be able to consider the construability principles that appropriate to be
applied for foundation design, when they read through the checklist at the beginning
of the design work. In addition, the designers also reviewed the foundation design
constructability, when they are using the checklist to assess their design work. So,
constructability inputs are injected and the design constructability is reviewed by
utilizing this kind of checklist that developed in this study. Appendix C listed out the
design phase’s constructability principles that being inserted in those features to be
checked.
However, other features to be checked that not yet being listed in that
checklist, also can be added up in the future, if the designers, client or contractor feel
that features need to be checked in order to promote or enhance the design
constructability.
6.4
Summary
Based on the development of building design constructability checklist for
assessment on building foundation design discussed in this chapter, the following
summaries can be made:
a)
Totally, there are 13 main features had been listed in the building design
constructability checklist. All main features are further described by
sub-features in order to let the users know what things are needs to be
considered and reviewed for enhancement of design constructability.
115
b)
Design phase’s constructability principles that being integrated in the
features to be checked are discovered and listed. Hence, when the
designers study through the checklist at the beginning of their design
and used it for design assessment purpose, the constructability of the
design will be inputted in the design consideration and reviewed during
the assessment.
116
CHAPTER 7
CONCLUSIONS AND RECOMMENDATIONS
7.1
Introduction
In traditional contracting system, a building design is separated from its
construction stage and the involvement of construction experts will only be
commenced after the project design stage is complete. Hence, this traditional design
process do not focused on the production of the contractor, where it is the
contractor’s responsibility to plan and match the design needs. As a result, many
design-related problems arise during the project design stage, such as the buildings
could not be built efficiently or constructed as designed. This study was carried out
to integrate constructability into the building design process that conducted within
the traditional contracting system. The findings from this study are concluded and
several recommendations for related future research are briefly explained in this
chapter.
7.2
Conclusions
The objectives of this study that stated in Chapter 1 have been reached from
the three phases of research exercises described in the research methodology. They
are:
117
a)
To determine the local construction industry’s current building design
process.
b)
To propose a model that integrates constructability to the general
building design process.
c)
To develop a building design constructability checklist.
Hence, the conclusions of this study are:
a)
The local construction industry’s current building design process flow
has been determined by conducting several structured interview with
the predetermined interviewees described in Chapter 3. Based on the
information collected from the each expert, three current building
design process models have been developed and presented in DFD
form. Then, a general building design process model is developed by
comparing, combining and generalizing those four current building
design process models. In briefly, the building design process consists
of 3 major processes, they are preliminary design, detailed design and
estimating costs. The sub-processes consist within the preliminary
design process are produce architectural preliminary design, produce
architectural schematic design, produce engineering preliminary plan,
and discussion. Meanwhile, the sub-processes consist within the
detailed design are produce detail architectural drawing, detail
engineering design, produce structural layout, and produce detail
engineering drawing.
b)
Based on the opinions from the four experts, an integration of
constructability principles into the general building design process
model is proposed by having a constructability checklist as the entity
and a review design constructability process in that model. The
constructability checklist, where the features to be checked promote
the design constructability, contributes constructability inputs into
determined points of the sub-processes and acts as a checklist itself to
the review design constructability process. Besides, the review design
118
constructability process is functioned to check and assess the design
constructability at the predetermined points of the design process by
using the constructability checklist.
c)
A building design constructability checklist for assessment on
foundation is developed. It is a tool that integrated with
constructability principles in the features to be checked, use for
integrating constructability in the design. Totally, there are 13 main
features to be checked, have been listed into the checklist. The subfeatures further describe all main features in order to let the users
know what things are need to be considered and reviewed for
enhancement of design constructability.
7.3
Recommendations for Future Research
The following suggestions are recommended for related future research.
a)
The constructability assessment framework proposed in this study is
limited to building project procured under the traditional contracting
system. Hence, it is recommended that similar framework should be
developed for other types of project, or the building project is
procured in other types of procurement system.
b)
The constructability checklist developed in this study is only limited
to enhance and assess the building foundation design. Further study
should be carried out to develop other building design constructability
checklists that can be used for assessment on other structural elements,
such as beam, column, slab and roof.
119
c)
It is not specified that those features and sub-features listed in the
foundation constructability checklist are the only features that need to
be considered and checked. Other relevant features to be checked,
which
can
promote
and
enhance
the
foundation
design
constructability, are recommended to be added in the future, so that
the checklist is more complete in terms of coverage.
d)
It was discussed in Chapter 2 that the design will improve as the
constructability principles were considered in the early stage of the
design phase. Since in this study there was no indication of actual
impact on the project that considered and reviewed its constructability
during the design phase, it is recommended that further work should
be carried out to determine the actual benefit gained from utilizing the
constructability integrated design process model.
120
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APPENDIX A
126
Universiti Teknologi Malaysia
Fakulti Kejuruteraan Awam
Interview Questions on:
Integrating Constructability into the Design Process
General
Generally, all building project will undergo several major stages, such as
conceptual and feasibility study, design stage, procurement stage, construction stage,
operation and utilization stage. In traditional contracting system, a building design is
separated from its construction stage and the involvement of construction experts
will only be commenced after the project design stage is completed. Consequently,
many design-related problems arise during the project construction stage, where the
buildings could not be constructed efficiently, or some could not be built as planned
or designed. These design-related problems can often be traced back to design
decisions that lacked of knowledge regarding on how the object would be built.
Hence, proper implementation of constructability review within the design process it
seems to be able to minimize or solve those design-related problems.
Constructability, or buildability in other word, means the extent to which the
design of a building facilitates ease of construction, subject to the overall
requirements for the completed building (CIRIA, 1983). It emphasis the designers to
incorporate constructability inputs and critiques as part of their design practice. Such
constructability inputs that had been identified in this study are:
• Carry out thorough investigation of the site;
• Design for minimum time below ground;
• Design for simple assembly;
• Encourage standardisation/repetition;
• Design for pre-fabrication, pre-assembly or modularisation;
• Analyse accessibility of the jobsite;
• Employ any visualisation tools such as 3D CAD to avoid physical interference;
127
• Investigate any unsuspected unrealistic of incompatible tolerance;
• Investigate the practical sequence of construction;
• Plan to avoid damage of work by subsequent operations;
• Consider storage requirement at the jobsite;
• Investigate the impact of design on safety during construction;
• Design to avoid return visit by trade;
• Design for skills available;
• Consider suitability of designed materials;
• Provide detail and clear design information;
• Design for early enclosure; and
• Consider adverse weather effect in selecting materials or construction methods.
Aims
The aims of this interview are:
i)
To determine the current design process flow of building project, which
procured under Design/Bid/Build contracting system.
ii)
To determine any constructability consideration or implementation within
the current design process flow.
iii)
To determine the best time of implementation for constructability review
process.
All information and responses you provided will be treated in confidential manner
and anonymously.
128
The Interview Questions:
1.
Generally, a building design process can be categorized into 2 major subphases, which are the preliminary design and detail design.
Based on your experience, can you explain in detail about when, how and
what the activities and workflows are normally being involved in preliminary
design of a building project (excluded civil or infrastructure works)?
2.
After the preliminary design, the building design will be proceed to detail
design, in order to produce a complete set of detailed drawings and
specification for procurement stage.
Based on your experience too, can you explain in detail about how and what
the activities and workflows are normally being involved in detail design of a
building project (excluded civil or infrastructure works)?
3.
Consideration of constructability during the design stage is one of the
alternative ways to minimize or solve various design-related problems.
Based on your experience and in your point of view, when is the building
project, within the design stage, should be injected with constructability input?
4.
Either the building design had injected with constructability input during the
design phase or they had been neglected, review of its constructability which
based on any one or more from the eighteen constructability principles
mentioned above, can discovered up the design’s constructability problem.
For example, constructability reviews can be carried out within the
preliminary design stage and/or detail design stage, after a certain work had
been done.
In your opinion, when is the appropriate time to conduct this constructability
review process?
5.
Normally, it is encouraged that the review or checking system shall be
carried out by other persons who are not directly involved in the design.
What is your opinion if a design is designed by the engineer or architect, and
the design’s constructability is checked by the same person who did the
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design? In other words, shall the constructability review be carry out by other
competent person, professional engineer for example, so that the review
system is carried out without any personal mistake?
6.
In this study, a constructability review checklist for building foundation’s
design is need to be developed for that reviewing system mentioned above.
Based on the eighteen constructability principles as printed on first two pages,
can you tick out which principles should be considered and reviewed during
the building foundation’s design stage?
Based on your experience, what features shall be checked for that foundation
design, by regarding to each constructability principle that you have selected
just now?
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APPENDIX B
131
BUILDING DESIGN CONSTRUCTABILITY CHECKLIST
Assessment on
: FOUNDATION
Project’s name
: _________________________________________________
1.
General characteristic of the surrounding
• Topographical map or landscape
• Existing planting or trees
• Existing or previous building
• Others infrastructure, e.g.: road, water,
electricity, drains and etc
• Survey plan
2.
Type of ground formation
• Cut and fill involved and slopes
3.
Adequacy of soil investigation information
• Geological survey maps
• Inspection of adjoining areas and site
exploration
• Availability of Borehole or Mackintosh
Probe Test records for adjacent area or
significant areas
4.
Adequacy of Borehole numbers (depends on
site condition)
• Numbers of boreholes
• Soil variability:
- uniform or variable
- frequency and type of sampling
• Any complexity of founding strata or
bedrock?
Not OK
Features to be checked
OK
Items
_________________________________________________
Remarks
Continue…
5.
Site exploration, such as geological formation
and subsoil strata
• Its nature, thickness, dip and variability
• Physical properties of strata
• Ground water level, peculiar ground water
movement, variation and chemical
composition
• Subsoil and bedrock profiling
• Adequacy of sampling and testing
6.
Consideration of site clearance:
• Underground services, such as power
lines and cables, telecommunication
cables and conduits, main and distribution
of water supply, sewer lines, tensioning
steels of RE wall.
• Overground items, such as protected or
gazette trees, structures and monuments
• Maintained adequate clearance between
those services and items.
7.
Site suitability of the selected foundation
system
• Its spatial requirement and constraint
• Individual space requirement
• Provision of convenience and services
• Consideration of accessibility (ingress,
egress and circulation)
• Consideration of adverse weather effect to
selected construction method
Not OK
Features to be checked
OK
Items
132
Remarks
Continue…
8.
Consideration of construction and/or testing
equipments and tools for the selected
foundation system.
• Accessibility of those equipments and
tools to the site (ingress, egress and
circulation)
• Versatile and ease to be fitted or parked in
the site constraints
• Availability of resources and skill for
installation, operation, maintenance and
dismantling
• Is the selected system well established in
the local market?
9.
Requirement to the environmental, health,
safety and others statutory compliance for the
construction
• Noise pollution
• Dust and suspended air particles
• Vibration control
• Temporary or permanent works and
protection to the neighbors
• Debris or spoils disposal and dumping site
Not OK
Features to be checked
OK
Items
133
Remarks
Continue…
10.
Minimize the complexity of foundation design
• The system to construct is available in the
local market
• Required method of construction is simple
• Consideration of repetitive construction
sequence
• Adequate allowance for construction
tolerances
• The design can be construct within
minimal time and depth of work below
ground
• The design supports modifications and
enhancement, such as ease of remedy for
remedial design and compensating works
11.
Construction materials to the selected type of
foundation
• Ease of availability of:
- type, size, grade, and quality of the
materials
- additives
• Skills availability and its workability in:
- handling and placement
- fabrication and assembly techniques
- safety during the foundation
construction
• Suitability of the designed materials to
soil condition and adverse weather
Not OK
Features to be checked
OK
Items
134
Remarks
Continue…
12.
Detail design and construction drawings
• If possible, design the foundation with
zero eccentricities between pile groups,
stumps and column.
• Standardization of the foundation and
stump size and depth; avoid odd
dimension that required addition works in
preparing the formwork
• Minimal variation or standardize the
standard detailing in:
- yield strength of reinforcement bars
- concrete grade
- pile’s types and sizes
- single pile, double pile or three pile…
- pilecap details
- stump
• Adequate and practical tolerance of
reinforcement bars and adjacent footings
• Anchorage bars are clearly shown
• Cross section of the foundation design
with other structural elements are clearly
shown
• All detailing information, notes and
specifications are clear, concise, complete
and understandable
13.
Clear markings and positioning
• Gridlines and boundaries are properly
identified and consistent with architectural
layout
• Footing base levels
• Top of footing or pilecap levels
Not OK
Features to be checked
OK
Items
135
Remarks
136
APPENDIX C
Items
Design Phase’s Constructability Principles That Being Inserted
1.
Features to be checked
Integrated
principles
General characteristic of the surrounding
• Topographical map or landscape
• Existing planting or trees
• Existing or previous building
Principle P1
• Others infrastructure, e.g.: road, water, electricity, drains
and etc
• Survey plan
2.
Type of ground formation
• Cut and fill involved and slopes
3.
Principle P1
Adequacy of soil investigation information
• Geological survey maps
• Inspection of adjoining areas and site exploration
Principle P1
• Availability of Borehole or Mackintosh Probe Test records
for adjacent area or significant areas
4.
Adequacy of Borehole numbers (depends on site condition)
• Numbers of boreholes
• Soil variability:
Principle P1
- uniform or variable
- frequency and type of sampling
• Any complexity of founding strata or bedrock?
5.
Site exploration, such as geological formation and subsoil strata
• Its nature, thickness, dip and variability
• Physical properties of strata
• Ground water level, peculiar ground water movement,
variation and chemical composition
• Subsoil and bedrock profiling
• Adequacy of sampling and testing
Principle P1
137
6.
Consideration of site clearance to:
• Underground services, such as power lines and cables,
telecommunication cables and conduits, main and
distribution of water supply, sewer lines, tensioning steels
of RE wall.
• Overground items, such as protected or gazette trees,
Principle P1 and
P8
structures and monuments
• Maintained adequate clearance between those services and
items.
7.
Site suitability of the selected foundation system
• Its spatial requirement and constraint
• Individual space requirement
• Provision of convenience and services
• Consideration of accessibility (ingress, egress and
Principle P2, P6
and P18
circulation)
• Consideration of adverse weather effect to selected
construction method
8.
Consideration of construction and/or testing equipments and
tools for the selected foundation system.
• Accessibility of those equipments and tools to the site
(ingress, egress and circulation)
• Versatile and ease to be fitted or parked in the site
constraints
Principle P6,
P11 and P14
• Availability of resources and skill for installation,
operation, maintenance and dismantling
• Is the selected system well established in the local market?
9.
Requirement to the environmental, health, safety and others
statutory compliance for the construction
• Noise pollution
• Dust and suspended air particles
• Vibration control
• Temporary or permanent works and protection to the
neighbors
• Debris or spoils disposal and dumping site
Principle P12
138
10
.
Minimize the complexity of foundation design
• The system to construct is available in the local market
• Required method of construction is simple
• Consideration of repetitive construction sequence
• Adequate allowance for construction tolerances
• The design can be construct within minimal time and depth
Principle P2,
P3, P4 and P14
of work below ground
• The design supports modifications and enhancement, such
as ease of remedy for remedial design and compensating
works
11
.
Construction materials to the selected type of foundation
• Ease of availability of:
- type, size, grade, and quality of the materials
- additives
• Skills availability and its workability in:
- handling and placement
- fabrication and assembly techniques
Principle P15
and P18
- safety during the foundation
construction
• Suitability of the designed materials to soil condition and
adverse weather
12.
Detail design and construction drawings
• If possible, design the foundation with zero eccentricities
between pile groups, stumps and column.
• Standardization of the foundation and stump size and
depth; avoid odd dimension that required addition works in
preparing the formwork
• Minimal variation or standardize the standard detailing in:
- yield strength of reinforcement bars
- concrete grade
- pile’s types and sizes
- single pile, double pile or three pile…
- pilecap details
- stump
Principal P3, P4,
P8 and P16
139
(continue from item 12)
• Adequate and practical tolerance of reinforcement bars and
adjacent footings
• Anchorage bars are clearly shown
• Cross section of the foundation design with other structural
elements are clearly shown
• All detailing information, notes and specifications are clear,
concise, complete and understandable
13.
Clear markings and positioning
• Gridlines and boundaries are properly identified and
consistent with architectural layout
• Footing base levels
• Top of footing or pilecap levels
Principal P16