THE CONSULTANCY FEE FOR STRUCTURAL DESIGN CHANGES OF
REINFORCED CONCRETE BUILDINGS IN OMAN
AMUR SALIM HAMOOD AL-HARTHY
UNIVERSITI TEKNOLOGI MALAYSIA

BAHAGIAN A – Pengesahan Kerjasama*
Adalah disahkan bahawa projek penyelidikan tesis ini telah dilaksanakan melalui kerjasama antara _______________________ dengan _______________________
Disahkan oleh:
Tandatangan :
Nama :
Jawatan
(Cop rasmi)
:
* Jika penyediaan tesis/projek melibatkan kerjasama.
Tarikh :
BAHAGIAN B – Untuk Kegunaan Pejabat Sekolah Pengajian Siswazah
Tesis ini telah diperiksa dan diakui oleh:
Nama dan Alamat Pemeriksa Luar : Assoc. Prof. Dr. Abd Rashid Bin Abd Aziz
Pusat Pengajian Bangunan & Perancangan
Universiti Sains Malaysia
11800 Minden
Pinang
Nama dan Alamat Pemeriksa Dalam : Assoc. Prof. Dr. Muhd Zaimi Bin Abd Majid
Fakulti Kejuruteraan Awam,
UTM, Skudai
Nama Penyelia Lain (jika ada) :
Disahkan oleh Penolong Pendaftar di SPS:
Tandatangan :
Nama : GANESAN A/L ANDIMUTHU
Tarikh :

THE CONSULTANCY FEE FOR STRUCTURAL DESIGN CHANGES OF
REINFORCED CONCRETE BUILDINGS IN OMAN
AMUR SALIM HAMOOD AL-HARTHY
A thesis submitted in fulfilment of the requirements for the award of the degree of
Doctor of Philosophy
Faculty of Civil Engineering
Universiti Teknologi Malaysia
MARCH 2006

This research work is dedicated to: my mother and wife who I owe them so much for their inspiration and encouragements and to my children who I had to turn down their entertainment just to find more time for this work.

Thanks to
for every thing I was able to achieve and for everything I tried but I was not able to achieve.
In preparing this thesis, I was in contact with many people, researchers, academicians, and practitioners. They have contributed towards my understanding and thoughts. In particular, I wish to express my sincere appreciation to my main thesis supervisor, Associate Professor Dr. Mohamad Ibrahim bin Mohamad for his valuable guidance; constructive advice; thoughtful comments and good friendship which have been all greatly appreciated. I also wish to record my greatest thanks to my co-supervisor Professor Dr. Abd. Karim Mirasa for his gratitude, inspiration and for his valuable suggestions. Without their continue support and interest, this thesis would not have been the same as presented here.
My sincere appreciation is extended to my colleague Ammar Al-Ajuli for his continues support and assistance especially during the difficult times. I am also indebted to the professionals who shared their time and experience during the interviews and the efforts from the industry practitioners who responded to the questionnaires. Their comments no doubt consolidated the findings of this research work.
Very special thanks to my parents and my family members for their irreplaceable giving and consistent motivation. My deepest appreciation is for my mother, my wife and my children for their love, patience and encouragement in which this research is dedicated to them.

Design changes in reinforced concrete buildings have for long time been a topic of prolonged arguments and frequent disputes due to their common phenomena of incidents in the construction industry. Although design changes in many cases are essential, clients, consulting engineers and contractors all have become increasingly worried about the negative parts that are associated with them. Design changes do not only affect the reliability of design but also increase the possibility of contractual disputes due to unpredictable delay and cost overrun on the original scope of work.
While the cost of modifying the construction scopes is well defined in normal contract documents, but the fee of engineering changes is yet to receive more attention. Therefore this research has been developed with the aim to investigate such issues and to develop an alternative approach in evaluating the fee of altering the original scope of design work. Extensive study was performed at the initial stage of this research work in term of interviews, case studies and questionnaire survey in order to identify the sources, causes and impacts of design changes on reinforced concrete buildings as well as to establish corrective actions and preventive measures to minimise the avoidable ones. Frequency analysis and non-parametric statistical technique employed in this research to analyse the qualitative and quantitative data.
It was found that engineering design changes are common in the industry and, in many cases, lead to excessive claims and disputes due to lack of appropriate and practical methods to assess their associated fee. Although there are various methods being used for assessing the fee of design changes, this study identified their limitations for practical use. Consequently, an alternative method for assessing the fee of the structural design changes has been developed in this research based on designing various type and complexity of low rise RC buildings. The developed method has been verified by a panel of experts by means of questionnaire survey and found to be practical, suitable and effective. Set of guidelines for improving consultancy design documents with respect to design changes and another set of guidelines for managing their claims have been also developed. These guidelines have been validated by panel of experts using Delphi technique. The result of the validation process provides encouragement to recommend the guidelines for practical implementation.

Perubahan terhadap rekabentuk asal bagi pembinaan bangunan konkrit bertetulang (RC) sering berlaku dan isu ini telah sekian lama diperbahaskan. Ia juga sering menjadi punca perbalahan dalam industri pembinaan. Walaupun perubahan dalam rekabentuk dalam keadaan tertentu adalah perlu dilakukan tetapi kesan negatif akibat daripada perubahan yang dibuat juga turut mebimbangkan pihak yang terlibat seperti klien, jurutera perunding dan kontraktor. Perubahan terhadap rekabentuk bukan sahaja meninggalkan kesan terhadap kredebilitinya rekabentuk itu sendiri malah boleh mendorong kepada berlakunya perbalahan kontrak disebabkan oleh kelewatan kerja dan perubahan kos akibat daripada perubahan daripada skop asal kerja. Lazimnya kaedah penilain terhadap perubahan kos bagi kerja pembinaan akibat daripada perubahan skop kerja agak jelas mengikut peruntukan yang sedia ada didalam kontrak pembinaan. Walaubagaimana pun kaedah penialaian kos terhadap perubahan bagi kerja merebentuk tidak begitu mendapat perhatian para penyelidik.
Oleh itu kajian ini telah dijalankan untuk mengenalpasti masaalah ini dengan lebih mendalam serta mengemukakan suatu kaedah alternatif bagi menilai kos perubahan bagi mengubahsuai rekabentuk asal yang dilaksanakan oleh pihak perunding. Pada peringkat awal kajian ini tela mengenalpasti punca, kesan dan kaedah penialain kos dalam proses membuat perubahan terhadap rekabentuk bagi sesabuah bangunan konkrit. Juga dikaji adalah kaedah yang boleh digunakan untuk mengurangkan keperluan membuat prubahan rekabentuk oleh pihak klien. Kaedah penyelidikan yang digunakan termasuklah sesi temubual, kajian kes dan menghantar borang soal selidik kepada responden. Kaedah analisa frekuensi dan kaedas Statistik Tak
Berparametar telah digunakan untuk membuat analisa data kualitatif dan kuantitatif yang digunakan dalam penyelidikan ini. Hasil dari kajian mendapati bahawa perubahan terhadap rekabentuk adalah sesuatu yang lazim berlaku dan dalam banyak kes menyebabkan berlakunya tuntutan tambahan yang berlebihan yang dibuat oleh perunding akibat daripada tidak ada kaedah yang sesuai untuk membuat penialaian kos yang praktikal dan wajar digunakan. Lanjutan dari itu hasil dari penyelidikan ini telah membangunkan satu kaedah yang sesuai digunakan untuk sebagai kaedah alternatif untuk membuat penialaian apabila berlakunya perubahan atau pengubahsuaian terhadap rekabentuk asal terhadap struktur bangunan konkrit bertetulang sederhana tinggi. Kaedah ini telah dipersetujui sebagai sesuai digunakan oleh panel para professional yang mempunyai pengalaman yang luas dalam industri pembinaan di Oman. Selain dari itu penyelidikan ini turut membangunkan satu garispanduan yang sesuai diterapkan dalam kontrak untuk mengemaskini lagi proses membuat perubahan rekabentuk dan menguruskan tuntutan yang dibuat berkaitan dengan perubahan yang dibuat tersebut. Garispanduan ini telah dibuat pengesahan dengan panel yang berpengalaman dalam industri pembinaan di Oman dengan menggunakan kaedah Delphi.

vii
TABLE OF CONTENTS
CHAPTER TITLE PAGE
DECLARATION OF THE STATUS OF THESIS
TITLE PAGE i
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
LIST OF TABLES xiv
LIST OF FIGURES xix
LIST OF SYMBOLS xxii
LIST OF APPENDICES xxiii
1 INTRODUCTION 1 and
1.3 Aim and Objectives 5
1.4 Scope and Limitations of the Research 6
1.6 Justification of the Research 7
1.7 Significance of the Study 10
1.8 Research Contributions 10
1.9 Organization of the Thesis 10

viii
2 DESIGN CHANGES 14
2.1 Introduction 14
2.2 Definitions of Design Changes 14
2.3 Classifications of Design Changes 15
2.5 Causes of Design Changes 20
2.6 Impact of Design Changes 28
2.6.2 Impact of Design Changes on Time 34
2.6.3 Impact of Design Changes on Productivity 36
2.7 Development for Improving the Management of 41
2.8 Chapter Summary 45
3 THE PRINCIPLE OF CONSULTING 48
ENGINEERING PRACTICE
3.1 Introduction 48
3.3 Definition of the Consulting Engineer 49
3.4 Reasons for Consulting Engineering Services 50
3.5 Services Provided by Consulting Engineers 52
3.5.1 Feasibility
3.5.2 Preliminary
3.5.3 Detailed
3.5.4 Tender Stage 54
3.5.5 Phase
3.5.6 Operation Phase 56
3.6 Methods of Charging for Consulting Services 57
3.6.2 Salary Cost Times Multiplier Plus 59
Non-Salary Cost method
3.6.3 Cost plus Fixed Amount Method 59
3.6.4 Per Diem Method 60
3.6.6 Retainer Method 64

ix
3.7 Chapter Summary 64
4 THE CONSTRUCTION INDUSTRY IN OMAN 66
4.1 Introduction 66 at Glance
4.3 Brief Highlights on Oman Economy 67
4.4 The Construction Sector in Oman 68
4.5 Consulting Engineering Services in Oman 71
4.6 Typical Scope of Consultant Services in 71
Omani Standards
4.7 Fee Assessment of the Design Changes in 75
Omani Standard
4.8 Chapter Summary 76
5.2 Literature Review 79
5.4 Case Studies 81
5.5.1 Design of the Questionnaire 83
5.5.2 Pilot Survey 85
5.5.3 Main
5.5.4
The Population and the Distribution of the 86
Questionnaire Survey
5.5.5 Methods of Analysing the Questionnaire Survey 88
5.6 Methodology for Development of an Alternative 92
Method to Assess the Fee of Structural
Design Changes
5.6.1
Design Parameters and Assumption for the 95
Building Design
5.6.2 Details and Classifications of the 95
Selected Buildings
5.6.3 Source of the Structural Design of the Buildings 96
5.6.4 General Structural System for the 97
Buildings of this Study

x
5.6.5 The Principle of the Adopted Structural Design 97
5.7 Questionnaire for Validating the Developed Method 99
5.7.1 Design of the Questionnaire 99
5.8 Development of the Guidelines 100
5.9 The Method of Validating the Developed Guidelines 102
5.9.1 Background of the Delphi Method 102
5.9.2 Selection of the Professionals for the 104
Delphi Questionnaires
5.9.3 Identifying the Number of Professionals for the 105
Delphi Method
5.9.4 Identifying the Number of Rounds for the 105
Delphi Method
5.9.5 Format of the Delphi Rounds for this Research 106
DATA
6.2 Interviews with Professionals 109
6.2.1 Discussions of the Interviews’ Results 109
6.2.2 The Occurrence of Design Changes 109
6.2.3 The Causes and Sources of Design Changes 118
6.2.4 The Impact of Design Changes 119
6.2.5 Existing Methods for Assessing the Fee of 119
Design Changes and their Limitations
6.3
6.3.1 Case
6.3.2 Case
6.3.3 Study
6.3.4 Causes of Design Changes 126
6.3.5 Sources of Design Changes 128
6.3.6 Impact of Design Changes on Cost 129
6.3.7 Impact of Design Change on Schedule 130
6.3.8 Existing Methods for Assessing the 131
Structural Design Changes

xi
6.4.1 Causes of Design Change Due to Clients 132
6.4.2 Causes of Design Change Due to Consultants 135
6.4.3 Causes of Design Change Due to Contractors 137
6.4.4 Sources of Design Changes 139
6.4.5 Impacts of Design Change 141
6.4.6 Corrective Actions and Preventive 144
Measures to Minimize the Avoidable
Design Changes
6.4.7
Preferences of Using the Existing 149
Methods for Assessing the Fee of Design Changes
6.4.8 Limitations of the Existing Methods 150
6.4.8.1 Limitations of the Man-Hours Method 151
6.4.8.2 Limitations of the Percentage of 153
Construction Method
6.4.8.3 Limitations of the Area Unit Rate Method 154
6.4.8.4 Limitations of the Lump-Sum Method 157
7 DEVELOPMENT OF THE PROPOSED METHOD 160
TO ASSESS THE FEE OF THE STRUCTURAL
160
7.2.1 Locations of the Structural Members 161
7.6 General Approach for Developing the Proposed Method 170
7.7.1 Preliminary Design and Drafting for 172
One Floor Buildings

xii
7.7.2 Detailed Design and Drafting for 176
One Floor Buildings
7.7.3
Preliminary Design and Drafting for 181
Two Floors Buildings
7.7.4
Detailed Design and Drafting for 185
Two Floors Buildings
7.7.5
Preliminary Design and Drafting for 189
Three Floors Buildings
7.7.6
Detailed Design and Drafting for 194
Three Floors Buildings
7.7.7
Preliminary Design and Drafting for 197
Four Floors Buildings
7.7.8
Detailed Design and Drafting for 202
Four Floors Buildings
7.7.9
Comparison of the Preliminary Design for 205
the Four Types Buildings
7.7.10
Comparison of the Detailed Design for 206 the Four Types Buildings
7.7.11
Comparison between the Preliminary and 208
Detailed Design
7.8 Design Based on STAAD Pro. Software 210
7.8.1 Preliminary Design and Drafting by 211
STAAD Pro for One Floor Buildings
7.8.2
Detailed Design and Drafting by 216
STAAD Pro for One Floor Buildings
STAAD Pro for Two Floors Buildings
7.8.4
Detailed Design and Drafting by 224
STAAD Pro for Two Floors Buildings
7.9 Suggested Method for Assessing the Fee of the 228
Structural Design Changes
7.10 Illustration for Using the Proposed Method 231
7.10.2 Example 2, Two Floors Building 234

xiii
GUIDELINES 242
FOR MANAGING DESIGN CHANGES
8.2 Initial List of Guidelines for Improving Consultancy 242
Design Documents
8.3
Initial List of Guidelines for Managing the Claims of 245
Design Changes
8.4 Validation of the Developed Guidelines 246
8.5.1 The Result of the Delphi Round One 247
Questionnaire
8.6 The Delphi Round Two Questionnaire 248
8.6.1 The Result of the Delphi Round Two 248
Questionnaire
8.7 The Delphi Round Three Questionnaire 252
8.7.1 The Result of the Delphi Round Three 253
Questionnaire
8.8 Chapter
9 CONCLUSIONS AND RECOMMENDATIONS 245
9.1 255
9.4 Suggestions for Further Research 263
REFERENCES 265
Appendices A - G 277 - 353

xiv
LIST OF TABLES
TABLE NO. TITLE PAGE
2.2 Importance Indexes of Sources of 19
Changes in Saudi Arabia
2.3 Sources of Changes, In Botswana, Gabrone 20
2.4 Causes of Changes in Hong Kong Building Projects 24
2.5 Causes of Changes in Botswana 27
2.6 Effects
2.7 Project
2.8 Causes
2.9 Quantitative
3.1 Converted Building Scale for Structural Works 63
in Buildings Expressed As A % of Building Cost
4.1 No. of Building Permits, Estimated Cost and Type of Building 70
5.1 Ranking System for the Questionnaire of this Study 89 using Likert (Ordinal) Scale
6.2 Result of the Interviews with Contractors 112

6.4 Result of the Interviews – Comparisons of Respondents 116
6.5 Case Study One - Causes, Sources and Fee of Changes 122
6.6 Case Study Two - Causes, Sources and Fee of 124
Design Changes
6.7 Case Study Three - Causes, Sources and Fee of 127
Design Changes
Studies Impact
Studies on
6.10 Main Scores (MS) and Ranks (R) for Causes of 133
6.11
6.12
Design Changes Due to Clients
Test for Agreement on the Ranking for Causes of 134
Design Changes Due to Clients
Main Scores (MS) and Ranks (R) for Causes of 136
Design Changes Due to Consultants
6.13
Test for Agreement on the Ranking for Causes of 137
Design Changes Due to Consultants
6.14
Main Scores (MS) and Ranks (R) for Causes of 139
Design Changes Due to Contractors
6.15
Test for Agreement on the Ranking for Causes of 139
Design Changes Due to Contractors
6.16 Main Scores (MS) and Ranks (R) for Sources 140 of Design Changes
6.17 Test for Agreement on the Ranking for Sources 141 of Design Changes
6.18 Main Scores (MS) and Ranks (R) for Impacts 142 of Design Changes
6.19 Test for Agreement on the Ranking for Impacts 143 of Design Changes
6.20 Main Scores (MS) and Ranks (R) for Corrective 145
Actions and Preventive Measures to Minimize the Avoidable Design Changes
xv

6.21 Test for Agreement on the Ranking for 149
Corrective Actions and/or Preventive Measures to Minimize the Avoidable Design Changes
6.22 Main Scores (MS) and Ranks (R) for Preference 150 of Existing Methods for Assessing the Fee of Design Changes
6.23 Main Scores (MS) and Ranks (R) for 151
Limitation(s) of the Man-Hours Method
6.24 Main Scores (MS) and Ranks (R) for Limitation(s) 153 of the Percentage of Construction Cost Method
6.25 Main Scores (MS) and Ranks (R) for 155
Limitation(s) of the Area Unit Rate Method
Limitation(s) of the Lump-Sum Method
7.1 Times, in Minutes, and Percentage of Time for 172
Preliminary Structural Design (One Floor Buildings)
7.2 Times, in Minutes, and Percentage of Time for 173
Preliminary Structural Drafting (One Floor Buildings)
7.3 Percentage of Time for Preliminary Structural 174
Design and Drafting (One Floor Buildings)
7.4 Times, in Minutes, and Percentage of Time for 177
Detailed Structural Design (One Floor Buildings)
7.5 Times, in Minutes, and Percentage of Time for 178
Detailed Structural Drafting (One Floor Buildings)
7.6 Percentage of Time for Detailed Structural 179
Design and Drafting (One Floor Buildings)
7.7 Times, in Minutes, and Percentage of Time for 182
Preliminary Structural Design (Two Floors Buildings)
7.8 Times, in Minutes, and Percentage of Time for 183
Preliminary Structural Drafting (Two Floors Buildings)
7.9 Percentage of Time for Preliminary Structural 184
Design and Drafting (Two Floors Buildings)
7.10 Time, in Minutes, and Percentage of Time 186
For Detailed Structural Design (Two Floors Buildings)
xvi

7.11 Time, in Minutes, and Percentage of Time 187 for Detailed Structural Drafting (Two Floors Buildings)
7.12 Percentage of Time for Detailed Structural 188
Design and Drafting (Two Floors Buildings)
7.13 Times, in Minutes, and Percentage of Time for 190
Preliminary Structural Design (Three Floors Buildings)
7.14 Times, in Minutes, and Percentage of Time for 191
Preliminary Structural Drafting (Three Floors Buildings)
7.15 Percentage of Time for Preliminary Structural 192
Design and Drafting (Three Floors Buildings)
7.16 Times, in Minutes, and Percentage of Time for 194
Detailed Structural Design (Three Floors Buildings)
7.17 Times, in Minutes, and Percentage of Time for 195
Detailed Structural Drafting (Three Floors Buildings)
7.18 Percentage of Time for Detailed Structural Design and 196
Drafting (Three Floors Buildings)
7.19 Times, in Minutes, and Percentage of Time for 198
Preliminary Structural Design (Four Floors Buildings)
7.20 Times, in Minutes, and Percentage of Time for 199
Preliminary Structural Drafting (Four Floors Buildings)
7.21 Percentage of Time for Preliminary Structural Design 200 and Drafting (Four Floors Buildings)
7.22 Times, in Minutes, and Percentage of Time for Detailed 202
Structural Design (Four Floors Buildings)
7.23 Times, in Minutes, and Percentage of Time for Detailed 203
Structural Drafting (Four Floors Buildings)
7.24 Percentage of Time for Detailed Structural Design 204 and Drafting (Four Floors Buildings)
7.25 Time, in Minutes, and Percentage of Time for 208
Preliminary and Detailed Structural Design and Drafting
7.26 Times, in Minutes, and Percentage of Time for 212
Preliminary Structural Design based on STAAD Pro
Design Software (One Floor Buildings)
xvii

7.27 Percentage of Time for Preliminary Structural Design 213 and Drafting Based on STAAD Pro Design Software
(One Floor Buildings)
7.28 Times, in Minutes, and Percentage of Time for Detailed 216
Structural Design based on STAAD Pro Design Software
(One Floor Buildings)
7.29 Percentage of Time for Detailed Structural Design 217 and Drafting based on STAAD Pro Design Software
(One Floor Buildings)
7.30 Times, in Minutes, and Percentage of Time for Preliminary 220
Structural Design based on STAAD Pro Design Software
(Two Floors Buildings)
7.31 Percentage of Time for Preliminary Structural Design 221 and Drafting based on STAAD Pro Design Software
(Two Floors Buildings)
7.32 Times, in Minutes, and Percentage of Time for Detailed 224
Structural Design based on STAAD Pro Design Software
(Two Floors Buildings)
7.33 Percentage of Time for Detailed Structural Design 225 and Drafting based on STADD Pro Design Software
(Two Floors Buildings)
7.34 Percentage of Time for Preliminary Structural Design 229 and Drafting (One Floor to Four Floors Buildings)
7.35 Percentage of Time for Detailed Structural Design 230
8.1
and Drafting (One Floor to Four Floors Buildings)
7.36 Questionnaire Result for the Validation of the POF Method 239
Delphi Round Two Results: Relative Importance 249
Level of each Guideline for Improving the Consultancy
8.2
Design Documents
Delphi Round Two Results: Relative Importance 251
Level of each Guideline for the Claims of the
Design Changes
xviii

xix
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Causes of Changes in Hong Kong 25
2.3 Effects of Change within Phase 39
3.2 Median Basic Fees as a Percentage of Net 62
Construction Cost
5.2 Distribution Profiles of Work Experience of the 88
Three Groups of Survey Respondents
7.1 Percentages of Time for the One Floor Buildings 176 at Preliminary Design Stage based on Manual Method
7.2 Percentages of Time for the One Floor Buildings at 181
Detailed Design Stage based on Manual Method
7.3 Percentages of Time for the Two Floors Buildings 185 at Preliminary Design Stage based on Manual Method
7.4 Percentages of Time for the Two Floors Buildings at 189
Detailed Design Stage based on Manual Method
7.5 Comparison between the Estimated Percentages of 193
Time to Design Main Structural Members for the Three
Buildings of Three Floors each at Preliminary Design Stage

7.6 Comparison between the Estimated Percentages of 197
Time to Design Main Structural Members for the Three
Buildings of Three Floors each at Detailed Design Stage
7.7 Comparison between the Estimated Percentages of Time 201 to Design Main Structural Members for the Three Buildings of Four Floors each at Preliminary Design Stage
7.8 Comparison between the Estimated Percentages of Time 205 to Design Main Structural Members for the Three Buildings of Four Floors each at Detailed Design Stage
7.9 Comparisons between Percentages of Time to Design 206
Main Structural Members for the Four Buildings at
Preliminary Design Stage
7.10 Comparisons between Percentages of Time to Design 207
Main Structural Members for the Four Buildings at
Detailed Design Stage
7.11 Comparison between Percentages of Time for 209
Preliminary and Detailed Design Stages
7.12 Percentages of Time for the One Floor Buildings at 214
Preliminary Design Stage based on STAAD Pro
Design Software
7.13 Comparison between Manual Design Vs. STAAD Pro 215
Design Software for One Floor Buildings at Preliminary
Design Stage
7.14 Percentages of Time for the One Floor Buildings 218 at Detailed Design Stage based on STAAD Pro
Design Software
7.15 Comparison between Manual Design Vs. STAAD Pro 219
Design Software for the Three Buildings of One Floor each at Detailed Design Stage
7.16 Percentages of Time for the Two Floors each 222 at Preliminary Design Stage based on STAAD Pro
Design Software
7.17 Comparison between Manual Design Vs. STAAD Pro 223
Design Software for the Three Buildings of Two Floors each at Preliminary Design Stage
7.18 Percentages of Time for the Two Floors Buildings 226 at Detailed Design Stage based on STAAD Pro
Design Software
xx

7.19 Comparison between Manual Design Vs. STAAD Pro 227
Design Software for the Three Buildings of Two Floors each at Detailed Design Stage
7.24 Original Ground Floor Roof Slabs/Beams Plan 235
7.25 Modified Ground Floor Roof Slabs/Beams Plan 235
7.26 Original First Floor Roof Slabs/Beams Plan 236
7.27 Modified First Floor Roof Slabs/Beams Plan 236
xxi

xxii
LIST OF SYMBOLS di - The different between the rank given by one group and the rank
given by another group f - frequency of responses to each score for each factor fn Total number of factors ranked by any two groups for any
given category
-
MS - Mean Score
N - Number of responses
Nf - total number of responses
NMM -
TNM Total Number of the structural Members
S - Score given to each factor as ranked by the respondents

LIST OF APPENDICES
APPENDIX TITLE PAGE
A Extract from Standard Form of Agreement and 277
Conditions for Consultancy Services for Building and
Civil Engineering Works (1987)
Survey Stage 284
E Questionnaire for Validating the POF Method 330
xxiii

CHAPTER
INTRODUCTION
1.1
Background and Rationale
Engineering design changes and their consultancy design fee assessment for reinforced concrete buildings’ design have, for long time, been a topic of prolonged discussions and frequent disputes between clients and their appointed consulting engineers. Design changes in their simple term are defined as any addition, omission or modification to the original scope of work in which a contract was signed
(Akinsola et al.
, 1997) or an adjustment to the completed design that may leads to change the original contract design fee (Baxendale and Schofield, 1996). These design changes might have great effect especially on cost and time and are likely to be a cause of claims and disruptions. In general, consulting engineers provide the necessary effort to develop the concept of the design to fulfil the intended use of the projects under design to their client’s requirements. An approval to preliminary design principle sets the basis for subsequent detailed design and for production of technical specification and construction documents.
It is common in the construction industry for almost all projects to go through various degrees of modifications at the design stage and more commonly during the construction. These changes are mostly caused by clients, in favour of getting new ideas or cost reduction on projects (Federal Construction Council, 1983; Kelvin,
1996). Design members have been also the main contributors of the design changes in the construction industry. They originate the changes to rectify their mistakes and

2 to improve or optimize their design (Hibberd, 1982; Choy and Sidwell, 1991).
Contractors may also introduce changes to adopt alternative construction methods that are of more familiarity (McDermott and Dodd, 1984; Yogeswaran, 1998) and suppliers, in order to meet the manufacturer’s recommendation to use a specific material (Emmitt, 2001).
The most common reasons that necessitate design changes are financial
(Ssegawa, et al.
2003), clients’ new requirements (Wilson, 1982), coordination problems (Bubshait et al.
, 1998), unclear scope of work (Austin et al.
, 2002), design errors (Leonard, et al.
, 1988), unexpected site conditions (Essex, 1996) and insufficient design information at the design stage (Ogunlana, et al.
, 1996). The possible changes could be minor related to design development which have no or relatively low cost effect on overall agreed design fees and could be major related to new ideas or changing the principle of the original design which, in turn, required replanning and re-designing that leads to a major cost effect.
There are numerous impact caused by design changes that influence the outcome of a project. Any inferior assessment, determination, misunderstanding or unavailability of relevant information or knowledge during the design stage leads inevitably to less than an optimum design that can be unnecessarily expensive and difficult to correct/alter at later stages of a project life cycle (Hashimoto, 1993). A successful project means that the project has met the required quality level, completed on time and within the allocated budget (Chan and Kumaraswamy, 1994;
Frimpong et al.
2003). Design changes usually divert these fundamental aims in the construction industry. These changes lead to great disruption on design and construction activities which, in turn, increase the chances for errors, increase cost, delay and decrease productivity.
Although design changes in many cases are essential for, as example, design development; clients, consulting engineers and contractors all have become increasingly worried about their magnitude and their impact that are associated with them. Design changes do not only affect the reliability of the design but also increase the possibility of contractual disputes due to the unpredictable delay and cost overrun on the original scope of work. The three case studies that have been

3 carried out from the construction industry in the Sultanate of Oman and were part of this research investigation have shown that the engineering consultancy fee can be as high as 189.8 percent of the original fee and the engineering consultancy time can increase by 195 percent.
While the cost of modifying the construction scopes is well defined in normal contract documents, the fee of engineering changes is yet to receive more attention.
Clients are not always willing to accept the variation charges set by consulting engineers mainly because they feel they are unjustifiable and consultants, on the other hand, feel that clients unreasonably reject or reduce the claimed amount. This can be predicted to some extend since the design changes are not easily quantified.
They are various methods in which consulting engineers have been using to assess the consultancy design fee associated with design changes These methods have been identified from the result of the interviews with the professionals working in the construction industry, from the case studies and from the questionnaire that all were carried out at the initial stage for this research work. These methods are the
Man-Hours method, Percentage of Construction Cost method, Area Unit Rate method and the Lump-Sun method. However the result of the interviews with the professionals working in the construction industry; the case studies; and the questionnaire survey that have been conducted as part of this research revealed that each one of these methods has various degrees of difficulties and limitations for implementation to the point where it becomes unpractical to adopt anyone of them.
To avoid the possible disputes arising from the lack of an affective way to evaluate the engineering consultancy fee of design changes, there is a need to develop a practical method for fee assessment of the structural design changes when they arise.
The primary aim of this research work is to develop an alternative method for assessing the consultancy design fee as a result of modifying the original structural design; to highlight suggestions for minimizing the avoidable design changes; and to provide guidelines for improving the consultancy design documents with respect of managing design changes

4
1.2 Problem Statement
Many articles have been written on the general subject of design changes.
Much of that research have focused on their nature and extend such as causes, sources and impacts, where others have concentrated on their legal aspects such as claims and disputes. Although design changes in many cases are essential for, as examples, design developments, design improvements, rectification of mistakes and resolution of problems related to unexpected circumstances, nevertheless, clients, consulting engineers and contractors all have become increasingly worried about the negative parts that are associated with design changes, and the poor recovery of the actual fee associated with their settlements (Jergeas and Hartman, 1994).
Nevertheless, design changes are still an ongoing problem that continues to raise the concerns in the construction industry. Such concerns stimulated this research and others to produce a series of reports, for example Latham report (1994) where variations have been identified as one of the main problems challenging the construction industry.
Almost all projects go through different level of modifications not only at the design stage but also during the construction. Previous studies such as the one by
Anderson and Tucker (1994) reveals that about one third of architectural/engineering projects missed cost and schedule targets as a result of design changes. Burati et al.
(1992) have shown that design changes increased the construction cost by an average amount of 12.4 percent of the total cost of the projects in the United Kingdom.
Chang (2002) reported that an engineering consultancy fee increased on an average of 24.8 percent based on four sampled projects in Taiwan as a result of design changes.
Delays have been identified as a key factor that increase the construction cost of the projects worldwide (Kartam, 1999). Design changes are one of the main causes that lead to such construction delays. Arditi et al.
(1985) found that 3.54 percent of the delays in public projects in Turkey were caused by design changes. In the UK, 49 percent of the delays are caused by factors related to design changes
(Sullivan and Harris, 1986). In Nigeria, this percentage is reported to be as high as
71 percent (Okpala and Aniekwu, 1988).

5
Consulting engineers are familiar with the methods of pricing their consultancy design services at the tender stage. These methods are well developed and well documented as it will be seen in the next chapter. When changes are introduced, there is a lack of an affective method to assess their fee. Normally consulting engineers either estimate their extra design fee for modifying the original design in a lump-sum basis or alternatively predict the most likely man-hours that are needed to carry out the change; or keep record of the man-hours they spend to execute the changes. The consulting engineers then submit the man-hours to their clients for payments. Clients, on the other hand, do not always accept the submitted man-hours because they feel the man-hours are overestimated due to lack of trust. At the same time, there is no well accepted alternative methods that might be used to quantify the design changes and hence to assess their fee. Such situations may increase the possibility of contractual disputes, affect the relationships and lead to dissatisfaction and disappointment to both the clients and the consulting engineers.
Recognizing these facts, there is an obvious need for in depth study to address these issues and to find a practical solution that might be used to assess the fee of modifying the original design changes. This research is a step toward satisfying this need.
1.3 Aim and Objectives
It is a well known fact that many design changes are most likely inevitable during the life cycle of the projects. These changes might be minor so that no major claims on fee or time extension takes place or might be major in which it results in main claims. While the original consultancy design fee is normally stated in the contract documents based on the tender submission and negotiation, there is no practical and acceptable method yet to assess the fee of modifying the original design. The primary aim of this research work is to formulate practical procedures for the assessment of the structural design changes so that an enhancement can be made to the existing practice. The result of this study will put forward practical means of avoiding and resolving the disputes caused by the lack of appropriate method of assessing the fee of design changes.

6
The review and investigation of this research work are to be carried out with the following objectives:
(1) To identify the sources, the causes, and the impacts of the design changes on reinforced concrete buildings;
(2) To establish corrective actions and preventive measures to minimise the avoidable design changes;
(3) To identify and evaluate the various methods for assessing the fee of the structural design changes and to identify their limitations;
(4) To develop an alternative method to assess the fee of the structural design changes for low rise RCC buildings;
(5) To develop guidelines to improve the consultancy design documents; and
(6) To develop guidelines to manage the design changes when they occur
1.4 Scope and Limitations of the Research
In this study, the proposed method for assessing the fee of the structural design changes is based on designing 12 number small scale low rise reinforced concrete buildings consisting of one floor to four floors. These buildings have already been constructed in the Sultanate of Oman prior to this study. The buildings under this research work have been designed using both manual calculations and
STAAD Pro 2003 software and have been drafted by AutoCAD 2000 software. The investigation and the scopes of this study were carried out in the Sultanate of Oman and hence limited to the typical standard details and normal practice in the country.
The finding can only be applied to these types of projects.

7
1.5 Brief Research Methodology
Research methodology provides a general plan and necessary steps to execute the research in a scientific manner. It is a logical model for collecting the information, analysing the data and interpreting the findings of the research. It is also the necessary methods that lead to achieve the aim and the objectives of the research.
To this end, Figure 1.1 outlines a flow chart for the methodology of this research. A more detailed research methodology is discussed in Chapter 5.
1.6 Justification of the Research
The idea of this work came from the past experience and knowledge on the extent of the problems and the size of the claims associated with the structural design changes. In many cases, design changes lead to disputes due to lack of proper guidelines to manage them and lack of appropriate methods on their fee variation assessment. The topic went through progressive refinement taken into consideration the interest in the area of the study, findings of previous works as well as the professional opinion from the industry in order to explore areas of dissatisfaction.
As a result of this initial investigation, the topic of this research is advanced to the state that it is delineated sufficiently for the aim and objectives of the research and importantly to make significant contribution to the subject.

INITIATION OF THE RESEARCH
Identifying the
Problem
Establishing the Aim
Identifying the
Objectives
LITERATURE REVIEW
Identifying the
Sources and Causes of Design Changes
Identifying the
Impact of Design
Changes
Identifying up to
Date Development for Managing
Design Changes
INTERVIEWS WITH
PROFESSIONALS
Verifying the Sources,
Causes and Impacts of
Design Changes
Identifying the Existing Methods for Assessing the Fee of Design
Changes and their Limitations
CASE STUDIES
Giving Actual Examples on the Size and Effect of
Design Changes
Demonstrating the
Limitations of the Existing
Methods in the Practice
Cont.
Figure 1.1 : Research Methodology Flow Chart
8

PILOT STUDY
QUESTIONNAIRE
SURVEY
Establishing the
Important Level of the Sources, Causes and Impacts of
Design Changes
Identifying the
Possible Preventive
Measures to
Minimise Design
Changes
Identifying the
Limitations of the
Existing Methods for
Assessing the Fee of
Design Changes
BUILDINGS DESIGN MANUALLY AND BY
STAAD PRO SOFTWARE AND DRAFTING BY
AUTOCAD FOR DEVELOPING AN
ALTERNATIVE METHOD FOR ASSESSING
THE FEE OF DESIGN CHANGES
VALIDATION OF THE DEVELOPED
METHOD BY QUESTIONNAIRE
SURVEY
DEVELOPMENT OF GUIDELINES
FOR MANAGING DESIGN CHANGES
VALIDATION OF THE DEVELOPED
GUIDELINES BY DELPHI METHOD
CONCLUSIONS,
RECOMMENDATIONS AND
SUGGESTIONS FOR FUTURE
RESEARCH
Figure 1.1 : Research Methodology Flow Chart (Continue)
9

10
1.7 Significance of the Study
The study is unique in the sense that no previous attempts have been made on the subject in spite of wide spread dissatisfaction associated with design changes, their impact and their fee assessment on reinforced concrete buildings. Surely it will improve the industry’s understanding on the negative aspects that are related to design changes and help to reduce the possible disputes in this regard. The study will improve the efficiency, effectiveness and satisfaction in the construction practice and it will make a contribution to the construction industry in general and especially to the consulting engineering firms by developing a practical method of charging for design changes. The study will help define the related issues and directions that need to be addressed in the future.
1.8 Research Contributions
The main contribution of this study to the body of knowledge falls on the following aspects: Firstly, the study gives emphasis on identifying the sources, causes and impacts of design changes on reinforced concrete buildings as well as on establishing corrective actions and/or preventive measures to minimise the avoidable ones. This study has developed practical and reliable method for fee variation assessment that might be implemented by professionals to assess the fee of changing or modifying the original design of reinforced concrete buildings. In addition, it is anticipated that the study will provide set of guidelines to improve the current design contract documents with respect to design changes and another set of guidelines to manage their claims
1.9 Organization of the Thesis
This thesis comprises four major components which can be summarized as follows:

11
•
Providing background, identifying the problems of design changes and reviewing their associated issues through literature searching;
•
Investigating and validating the main topics related to this research work through interviews with the professionals working in the construction industry, case studies and a questionnaire survey;
•
Making a contribution to the body of knowledge by developing an alternative method to assess the fee of the structural design change when they occur; and
•
Providing practical guidelines to manage design changes.
The four main components of the research are presented in nine chapters and are briefly described as follow:
Chapter 1 introduces the background of the research, its aim and objectives . It also discusses the brief research methodology used; the research justification; the significant of the study; the contributions; the scope of the research and a brief summary on the structure of the thesis.
Chapter 2 presents the findings from the literature review. It focuses on the issues of design changes which include the following:
• definitions and classifications of the design changes;
• sources, causes and impacts of the design changes; and
• new developments for managing design changes
Chapter 3 focuses on the discussion related to the principle of consulting engineering practice. The emphasis is given to these issues:
• the definitions of the clients and the consulting engineers
• the reasons for consulting engineering services
• the services provided by the consulting engineers

12
• the method of charging for consulting engineering services
Chapter 4 presents an overview of the construction industry in the Sultanate of
Oman from which the majority of the data for this study has been carried out. It gives basic information about Oman as a country; brief highlights on Omani economy; the construction sector in Oman and the consulting engineering services in the country.
Chapter 5 discusses the methodology adopted for this research. It starts by discussing the method used to justify the need for this research through the interviews with the professionals, case studies and questionnaire survey. Then it discusses the method used for data collection. An explanation was given to each method in term of their relation to the study, selection criteria and the anticipated result of each method.
Chapter 6 presents the data collection for the initial investigation to establish the extent of the problems associated with design changes and to justify the need for this research as perceived by the professionals in the industry. Interviews with professionals, three case studies and two stages questionnaire survey have been conducted and their results were presented in this chapter. In the interviews and in the case studies, the main problems of design changes have been identified as well as their causes, sources and impacts on the projects. From the results of the questionnaire survey, the significant level of the causes, sources and impacts of design change were identified along with the possible corrective measures to minimise them. The limitations of the existing methods are presented in this chapter as well.
Chapter 7 presents the development of the proposed method to assess the fee of the structural design changes in RCC buildings. It starts by highlighting the general approach that has been adopted for generating the data. The results have been shown in tables and illustrated graphically for comparisons. From the obtained data, a method for assessing the fee of the structural design changes has been developed.
Practical examples to illustrate the use of the proposed method are provided. The

13 chapter also provides the result of the questionnaire survey that has been conducted for validating the developed method.
Chapter 8 discusses the development of guidelines to manage design changes. It also provides in details the findings from the Delphi study that has been used as a method to validate the developed guidelines.
Chapter 9 concludes the results of the research. Discussions are made on the achievement of the objectives of the study, on the contribution of the research to the existing knowledge and recommendations are made for future research on the subject.

CHAPTER 2
DESIGN CHANGES
2.1 Introduction
In order to fully understand the resulting problems caused by changes, firstly their sources, causes and impacts need to be addressed. This will lead to better evaluation and management of the factors influencing their occurrence which can be minimized and better monitoring of these factors which cannot be avoided.
Providing a comprehensive background to cover these issues is an important task to set up a solid base for their assessment. As a first step toward this objective, this chapter reviews in depth and up to date the available research work and covers the principal of the design changes on RCC buildings, their sources, causes and impacts on the life cycle of the projects as well as the previous attempt to manage them that exist on the mater.
2.2 Definitions of Design Changes
Design change whether in the design or in the construction is simply defined as any change to the basis on which the contract terms were initially defined and endorsed (Baxendale and Schofield, 1996). This includes not only changes to the work or matters relating to the work in accordance with the provision of the contract but also changes to the working conditions themselves. Burati et al., (1992) defined

15 the change as a directed action altering the currently established requirements which includes changes in the design, fabrication, construction, etc. and materially affect the approved requirements, the basis of design, the existing scope of the contract plans and specifications. Akinsola et al., (1997) have defined the change as any modifications or changes that made to the original scope of work after the contract has been awarded. This definition includes: additions; omissions or adjustments to the original design; drawings; specification; contract documents; programme; method and sequence of executing the work. Turner (1984) stated that changes are
“changes within a contract” and not “changes of the contract”. In the later case, it might be more appropriate for both parties to sign a new contract. He further added that changes relate to firstly, changes to the work itself and secondly, to the means of getting the work done.
For the purpose of this study, all the above definitions are within the nature of this research work. The developed method that was proposed for assessing the fee of changing the original structural design (as it will be seen in the forthcoming chapters) is applicable to all design changes as defined above.
2.3 Classifications of Design Changes
Different classifications have been used in literature to define the design changes depending on their nature, effect and occurrence in the life cycle of the project. Gilbreath (1992) categorised the changes into two groups: formal changes and informal changes. He defined the formal changes to be the ones that are generally identified before they come in effect, based on a planned and deliberated choice by the owner and documented before they are executed by a formal instruction to change or modify the agreed scope of work. Alternative to the original design that causes revision to the construction drawings or specification is an example of formal changes. Informal changes are the ones often identified after the fact and are based on unexpected event and unplanned choice by the owner. They lead to execution of the work differently or performed task differently from that which require by the contract or which could be normally anticipated. Unexpected

16 acts of third parties such as subcontractors, material suppliers or other forces beyond the control are all examples of informal change
Fisk (2000) has used similar approach to classify the changes. He divided them into two basic groups: direct changes and constructive changes. In direct changes, the owner directs the consultant or the contractor to do works that are not specified in the original contract or the owner increases/decreases the specified scope of work which, in turn, leads to modification to the design documents. In this definition, direct changes are similar to the formal changes term that used by
Gillbreath (1992). Constructive changes, on the other hand, are an informal act resulting in modification to the work caused by act or failure to act by the owner that increases the cost and/or time to perform certain activities. Some examples of constructive changes, as listed by Fisk (2000) are defective plans, errors in specification, engineering interpretation of the contract clauses and higher standard of work than specified and change the method of doing the work. CII publication 6-
10 (1990) have added the term “cardinal changes”. It is defined as the change outside the original contract and should be executed only after negotiation and agreement.
Cox (1997) has stated that the “formal changes” wherein the owner issues a document titled “change order” that in some way modifies the contract terms, plans or specification. In addition he defined the “constructive changes” to be the one where extra-contract work performed either through oral or implied owner directives, or a result of problems for which the owner is responsible. Examples of the more common types of “constructive change” as stated by Cox (1997) are extra works to overcome incomplete or inaccurate documents and changes that arise from owner’s
“informal” approval of works or oral directive to perform works not otherwise required by the contract. Finally, “Cardinal changes” are changes that result from carrying out substantial amount of works out side the scope of the original contract which can be a single change or series of changes that lead to a significant deviation from original contract scope.

17
Defence Construction Canada’s (DCC) administration manual (DND, 1992) classified the changes based on their nature and origin. They have used the terms construction changes and design changes. Construction changes are those which caused by unforeseen site condition and do not require redesign or the ones that caused by construction errors which require rectification by the contractor or omissions of non-structural activities. Design changes are classified as the changes resulting from a modification within or out side the original scope of work and require re-design and revision to the contract documents. Changes can also be classified as required changes or elective changes (CII special publication 43-1,
1994). Required changes are the ones that must be implemented and are necessary to meet the basic and define objectives, regulatory, legal requirements, defined safety and engineering standards. Elective changes are those that may or may not be implemented and hence not mandated. They are typically introduced to enhance the project and not required to meet the original project objectives.
2.4 Sources of Design Change
Significantly increasing frequencies and magnitudes of design changes have accompanied the growth of construction activities worldwide. In spite of the amount of effort that carried out in the recent years to reduce the number of changes, yet it is a familiar characteristic in construction projects all over the global. Clients, architects, design members, and contractors all originate changes.
In the United States, the Federal Construction Council (1983) investigated the reasons for change in the construction process on federal projects. It concluded that wrong decisions by using agency (client’s representative) were the most significant sources of excessive changes and its associate cost implications. Kelvin (1996) cites owner's change of mind is the prime source of changes in residential housing projects. In the UK, Newcombe et al., (1982) found that 72 percent of the changes by number were originated by the design team. Hibberd (1982) carried out a research work into building contracts changes. His finding as derived from the
United Kingdom (UK) construction industry is presented in Table 2.1.

18
Table 2.1 : Actual Causes of Changes in the UK (Hibberd, 1982)
Source of Change
1. Designer (Architect)
2. Employer – forced
3. Employer – choice
4. Contractor
5. Design Management (Design members)
defect in design
inadequate consideration of design
incorrect assessment of brief
defects in documentation
unnecessary
6. Unforeseen
Percentage
(By Number)
19%
1%
10%
3%
9%
25%
6%
16%
5%
6%
Similar effort has been made by McDermott et al., (1984). In this study, 16 building projects were examined and the potential sources were classified into three categories, internal, external and non-allocated. He clarified that the internal sources consist of clients, architects and design members contributing design changes of 3 percent, 38 percent and 30 percent respectively. For external sources, 16 percent of the changes have caused by client’s body, 16 percent by local/planning authorities and 5 percent by contractors. Non-allocated sources represent 4 percent of the total changes.
In Australia, Bromilow (1970) investigated 25 completed construction projects to find out the sources of design changes. It was concluded that the two largest sources by value were the clients (41 percent) and the design team (25 percent). Choy and Sidwell (1991) evaluated 32 case studies to investigate the sources and extent of changes in Australian construction contracts in particular changes due to bills of quantities. The result of this work shows that the major sources of design changes in Australian projects by number were the design team (51 percent) and client’s sourced design changes to meet new requirements and preferences (16 percent) of the total design changes that have been issued for the investigated projects. The point to be noted from the two studies is the approach that

19 used for each one. The work done by Bromilow (1970) is related to the cost of the changes where the study by Choy and Sidwell (1991) is related to the number of the changes. Hence, the percentage wise for each counterpart source came out in contrast.
In Saudi Arabia, a study of a field survey in large building projects was conducted by Al-Dubaisi (2000). According to this work the owner is the main source of changes specially changes on plans, materials and/or construction procedure. He ranked the consultants to be the second major contributors to changes by generating conflicting design documents or through changes in design after the award of contract or through errors in the design, where the contractors received the third rank. The statistical result of this study is reproduced in Table 2.2.
Table 2.2 : Importance Indexes of Sources of Changes in Saudi Arabia
(Al-Dubaisi, 2000)
Source
Owner originated
Importance Index
50.44
Designer originated
Contractor originated
40.65
30.76
Others 25.49
In Botswana, Ssegawa et al., (2003) showed that the main sources of changes on building projects are the clients and the architects due to financial, aesthetic and design improvement reasons, while for the contractors it is the feasibility of the construction. The main finding of this research work is shown in
Table 2.3.

20
Table 2.3 : Sources of Changes, In Botswana, Gabrone (Ssegawa, et al., 2003)
Sources of Changes (No. of Responses)
Cause of Change
Client Arch. Contract. Other
Finance
Design
Change in drawings
Feasibility
Increment weather
Aesthetic
Geological/Geotechnical
Finance
Design
Change in drawings
Feasibility
Increment weather
Aesthetic
Geological/Geotechnical
25
-
-
-
-
12
-
16
21
-
21
-
-
-
-
24
24
-
-
6
-
11
-
17
-
-
-
-
-
-
3
-
-
-
-
-
-
-
-
-
-
5
Finance
Design
Change in drawings
Feasibility
Increment weather
Aesthetic
Geological/Geotechnical
24
-
-
-
-
22
-
3
25
22
5
-
4
6
-
2
5
20
-
1
16
2
-
-
5
-
-
-
2.5 Causes of Design Change
Various causes of changes have been identified by many researchers in different regions. Independent of the country of the study, most of these causes appear to be similar in nature yet different in magnitudes and orders.
Wilson (1982) in his study "Prevention and Resolution of Construction
Claims" has contributed the majority of the construction claims as caused by the introduction of extra work by the clients or their representative during the
-
-
6
-
2
3
3
6
-
-
-
-
6
5

21 construction stage. McDermott (1984) in his investigation of the 16 building projects in the UK stated that communication of information in the design process contributes one of the main causes of change within the investigated buildings. He related the percentage of changes that caused by the above factor to its timing of occurring. He concluded that 4 percent of the changes occurred at the briefing stage, 9 percent at preliminary design stage, 57 percent at detailed design stage and 15 percent during construction in which all contributed to communication and co-ordination problems.
Poor communication in the design intent and rationale has been also reported by
Caballero et al., (2002). They have reported that this cause of design change results in unwarranted design changes and hence unnecessary liability claims, increase the design time and cost, and inadequate pre- and post-design specifications.
An analysis of the generation and documentation process of the information reveals that propagation of design changes constitutes a main source for design deficiency. The large amount of design data that is generated within the typically multidisciplinary design environment makes managing and co-ordinating the information a very challenging task. As a result, the chances for design deficiency increase with the increase in the complexity of the projects. Bubshait et al., (1998) defined the design deficiency as any deficiency in the drawings and/or the specifications that results in a facility which will not adequately perform its intended mission.
Kirby et al., (1988) have identified three major causes of the contract modifications as follow: (1) design deficiency; (2) user requested changes; and (3) unknown site conditions. This study has also revealed that 56 percent of all contract modifications are concerned with correcting design deficiencies. Lutz et al., (1990) have categorized the design deficiencies as one of the following three types: (1)
Contract documents conflict (e.g. discrepancy between drawings and specifications);
(2) interdisciplinary co-ordination errors (e.g. conflict problems of architectural, structural, services drawings); and finally (3) technical compliance discrepancies
(e.g. non-adherence to the appropriate design guidelines, technical specifications and building codes). These deficiencies do not only lead to design changes but also result in altering the construction work which, in turn, may lead to contractual

22 disputes, cost overruns, time delay, compromise to quality, frustration and client dissatisfaction (Mokhtar, 2002).
Diekmann and Nelson (1992) examined construction claims for their frequency of occurrence, cost and type. They found that 46 percent of the claims were due to design changes as a result of design errors and 26 percent were either non-compulsory or mandatory changes. Thus, 75 percent of all contract claims can be traced to design changes, extra work and errors. Similar works have been carried out by Weston (1991), Gilbreath (1992) and Al-Dubaisi (2002) to identify the likely sources of design changes. According to these studies, the most common causes of changes include the followings:
ƒ
Change of scope of work by owners;
ƒ
Owner financial difficulties ( lead to reduction in the scope of work);
ƒ
Owner change of schedule ( to meet his financial commitment);
ƒ Ill defined project objectives ( require design improvement);
ƒ
Substitutions of materials or procedures;
ƒ
Conflict between contract documents;
ƒ
Change in design due to various reasons;
ƒ
Lack of co-ordination between the design members;
ƒ Result of value engineering process;
ƒ
Tendency to adopt new technology at the construction stage;
ƒ
Different and un-expected site condition;
ƒ
Contractor financial difficulties;
ƒ Lack of appropriate equipments;
ƒ Defective workmanship;
ƒ
Safety considerations;
ƒ
Weather condition;
ƒ
New Government regulations;
ƒ Design mistakes; and
ƒ Unclear contract clauses (miss interpolations)

23
Ogunlana and Promkuntong (1996) in their survey of the delays experienced in high-rise building construction projects in Bangkok, Thailand have contributed the delay as caused by incomplete information during the tender stage which resulted in extensive changes during the construction. They have added that since drawings and specifications have been issued in urgent bases to meet bid dates, a large margin of errors and omissions resulted and hence design changes were necessary during the construction to rectify the design mistakes and to finalize the clients' requirements.
Essex (1996) addressed the matter of uncertainty of subsurface ground conditions in the construction industry that continue to cause major disputes as a result of altering the original contract documents. In this regard, he added that owners have been unwilling to authorize adequate geologic exploration programs or to take the responsibility for unanticipated ground conditions, engineers have often prepared incomplete or inconsistent plans and specifications and contractors have tended to be excessively optimistic in their attempts to be the low bidder.
Akinsola et al., (1997) identified four main causes that influence the magnitude and frequency of changes based on analysis of 46 completed building projects in the UK, namely client characteristics (especially un-experience of building design and construction process), project characteristics (such as the type, size, degree of complexity and duration), project organization (includes the length of the design period, amount of completed construction drawings and contract documents before tendering, type of contract and validity of information provided) and environmental factors (such as the effect of the economy, political factors and the level of technology available at the region). Leonard, et al., (1988) suggested that the three major causes of changes in the construction are design errors & omissions (65 percent), design changes (30 percent) and unforeseen conditions (5 percent). Yogeswaran (1998) investigated the causes of changes in building projects in Hong Kong. This research is based on questionnaires survey, interviews and case studies for four different building projects. The result of this work is shown in Table
2.4 and Figure 2.1. Furthermore, the specification of building material is an important element but neglected area in the design process which if not correctly specified may leads to major design changes (Emmitt, 2001).

Table 2.4 :
Project A
Designer-
Change of
Design to suit
Site Condition
Designer-
Improved
Design
Design
Error
Employer-
Request to
Change
Design
Contractor-
Request
Further
Details
Monitoring
Works e.g.
Temp. Test &
Safety
Interface
Works
Request
Obstruction-
Existing
Utility
Clash-
Proposed
Utility
Delayed
Instruction
Abortive
Works
S.I Not Used
Total
Number of
Site
Instructions
Project B
Project C
Project D
Total
ƒ
ƒ
ƒ

120%
100%
Causes of Variation Series1
Series3
Series2
Series6
80%
60%
40%
20%
0%
1 2 3 4 5 6 7 8 9 10 11
Causes
Designer-
Change of
Design to suit
Site Condition
Designer-
Improved
Design
Design
Error
Employer-
Request to
Change
Design
Contractor-
Request
Further
Details
Monitoring
Works e.g.
Temp. Test &
Safety
Interface
Works
Request
Obstruction-
Existing
Utility
Clash-
Proposed
Utility
Delayed
Instruction
Abortive
Works
Figure 2.1 :

26
Love et al., , (2002) have used a case study in one of the Australian residential blocks project to identify the factors influencing a project's performance and they introduced systems dynamics to better understand changes and rework in construction project management systems. In this case study, they have interviewed the architect and engineers that have worked in the project along with other documented sources to derive the data for the study. They have found that design changes have been introduced due to many reasons including inaccurate, conflicting and incomplete information contained within the original contract documents. In addition, both the interviewed architect and the engineers stated that the program they were given was unrealistic as they were allocated only limited time period to prepare contract documentation. This short period for designing resulted in numerous design errors and conflicting drawings and specifications. Furthermore, design changes as a result of error detection during construction were found to be common occurrences. Also, a significant amount of rework occurred as the entire mechanical exhaust system for the basement car park had to be re-designed because it did not comply with the building code of Australia.
Many researchers have contributed the lack of proper design briefing as the main causes of design changes. Comprehensive and accurate briefing at the design phase is critical to the success of both the design and the construction which in turn reduce the chances of modifying the original design at later stages. Briefing involves understanding the client's needs and expressing them in a way that will ensure compatibility between the client's vision of the projects and the resulting product. In this regard, some problems do exist in the construction industry which involves the gap of common understanding between the clients and the designers. Some of these problems have been highlighted by Austin et al., (2002) which include: (i) the lack of proper guidance and support from the designers to their clients; (ii) the difficulties of the designers to capture client's needs and turning over the conceptual design options to their clients; (iii) the lack of common technical language in some cases between the clients and the designers which obstruct the communication and the exchange of the information between them.

27
Ssegawa et al., (2003) carried out a study in construction changes on building projects in Botswana, Gabrone. This study was based on a questionnaire that has been used to obtain opinions of architects and contractors working in the construction industry. The questionnaire was distributed to 20 firms from each group selected randomly around Gabrone City. The questions in the questionnaire required respondents to make a ranking corresponding with the frequency of the occurrence
(FO) ranging from slightly (1) to very often (4). The result related to the causes of the changes is shown in Table 2.5
Table 2.5 : Causes of Changes in Botswana, Gabrone (Ssegawa et al., 2003)
Omissions Additions Substitutions
Cause of Change
FO Rank FO Rank FO Rank
3. Change in drawings
3.8 1 2.8 3 3.8 1
3.5 2 3.9 1 3.2 2
2.0 6 2.6 4 1.3 7
3.4 3 1.6 6 2.6 5
1.0 7 1.8 5 1.4 6
2.2 5 3.6 2 3.6 3
7. 2.7 4 1.2 7 2.9 4
From the above table, respondents indicated that the main causes of omissions are for financial reasons which turned up at the first rank with frequency of occurrence (FO) of 3.8. Design changes came up in the second rank (FO: 3.5) followed by the feasibility of construction reasons (FO: 3.4).
Geological/geotechnical and aesthetic reasons scored lower values with FO of 2.7 and 2.2 respectively. For addition, respondents indicated that they occurred because of mainly design (FO: 3.9) and aesthetic reasons (FO: 3.6). Geological/geotechnical and feasibility of construction caused fewer additions. It can be also seen from the
FO scores, respondents believed that substitutions are caused mainly by financial reasons (FO: 3.8), design changes (FO: 3.2) and aesthetic reasons (FO: 3.6).

28
2.6 Impact of Design Change
Design changes have become an everyday occurrence in the construction industry. It is widely acceptable by clients, consulting engineers and contractors that changes have an effect on design and construction, but these effects are difficult to quantify and frequently lead to disputes if there is no mature understanding between the concerned parties exit in the matter. Clients and consulting engineering firms in the construction industry have difficulties identifying, with accuracy, the magnitude and the impact of the design changes. These difficulties increases the consulting engineers' risks when negotiating the fees of the design changes, makes clients more suspicious of consulting engineers' negotiation position, increase the chances that design changes may not be settled and may turn into claims and/or disputes.
There are numerous effects caused by design changes that influence the outcome of a project. Any inferior assessment, determination, misunderstanding or unavailability of relevant information or knowledge during the design stage leads inevitably to less than an optimum design that can be unnecessarily expensive and difficult to correct or alter at later stages of a project life cycle (Hashimoto, 1993). A successful project means that the project has met the required quality level, completed on time and within the allocated budget (Chan and Kumaraswamy, 1994;
Frimpong et al., 2003). Design changes usually divert these fundamental aims in the construction industry. These changes lead to great disruption on design and construction activities which, in turn, increase the chances for errors, increase cost, delay and decrease productivity.
Several criticisms of the industry are generated when projects take far longer than planned and cost more than expected (Southgate, 1988; Mobbs, 1989). A survey reveals that about one third of architectural/engineering projects miss cost and schedule targets as a result of design changes (Anderson and Tucker, 1994). There have been few instances where an engineering design was so complete that a project could be built to the exact specifications contained in the original design documents
(Smith 1996). It was found that the number of design changes per project was the highest for Design-Build projects and the number of construction changes per project was the highest for traditional projects (Cariappa, 2000). In the traditional projects,

29 the contractor relies on the drawings and specifications provided by the owner.
Hence any changes occurring due to errors, omissions or unexpected site conditions, as examples, are transferred to the owner.
Many construction problems are due to design defects which necessitate the need for design changes at later stages (Bramble and Cipollini, 1995). Therefore, owners, designers and contractors are all certainly concerned about the impact resulted from the changes.
A study by Finke (1998) in his effort to find a better way to estimate and reduce disruption in the construction projects has suggested that changes can cause changes in working conditions through at least six different fundamental mechanisms:
•
Resources diversions or skill strength, requiring that the changed and unchanged work use the same resources and be performed at the same time;
•
Work area congestion, requiring that the changed and unchanged work be
performed in the same area be performed at the same time;
•
Stacking of trades, requiring that the changed and unchanged work be
performed in the same area, be performed at the same time, and represent different types of work;
•
Dilution of supervision, requiring that the changed and unchanged work be performed at the same time and have the same supervision;
•
Interruptions of otherwise continuous work, requiring that the changed work forces in-progress unchanged work to be temporarily stopped; and
•
Delay, requiring that the change forces unchanged work to be performed at a different time than would otherwise have been the case, and the unchanged/delayed work, now acting as the changed work causes one of the five changes working conditions listed above.
Trickey and Hackett (2001) identified the challenges of changes as the establishment of the value of the:
•
Change itself;
•
Effect of the change on other work; and

30
•
Loss and expense directly experienced arising from regular progress of work having been materially affected due to the execution of the change and for which its reimbursement is not covered by any other part of the contract.
Ssegawa et al., (2003) investigated the effects of changes on buildings projects in Botswana. A questionnaire, with close-ended questions, was used to solicit opinions of architects and contractors on the issue. Fifteen (15) contractors and twelve (12) architects from each category responded. A frequency of occurrence
(FO) index was constructed with a minimum value of 1, and maximum value of 4.
The result of this study is shown in Table 2.6 bellow. According to this result, both the contractors and the architects confirmed that their firms have been involved in some kind of change on all projects they have worked on since their response to this question scored 4.0. The two groups also confirmed that changes affect the sequence of the work program since they have scored 2.7 and hence the completion time and cost (3.6 each).
Table 2.6
: Effects of Changes on Projects (Ssegawa et al., 2003)
Question
Frequency of
Occurrence (FO) Index
1. How often do you encounter changes on building
projects?
4.0
2. How do changes affect the following?
i) Project program
ii) Time iii) Cost iv) Quality
3.7
3.6
3.6
2.3
2.1 3. How often do you encounter disputes?
4. Which areas normally cause disputes?
i) Ascertaining losses arising from the
changes
ii) Valuations
iii) Acceptance of instructions
iv) Final account
3.8
2.9
2.5
2.4

31
Elinwa and Buba (1993) have identified four factors that influence the changes. They are:
•
Size of the project;
•
The difference between the low bid and the initial budget estimate;
•
The type of construction; and
•
The level of competition
The level of impact caused by design change is greatly related to the timing of issuing the instruction to execute them (Leonard, 1988). Changes made at later stage cause more disruption to projects as a whole. Alternation to the contract documents that made before the construction tend to have less effect on cost, time and productivity compared to the ones that made at the construction stage or after the execution of the work.
2.6.1 Impact of Design Change on Cost
The impacts of design changes on cost vary widely from project to another.
Although there have been cases where change in the project cost counted for as high as 100 percent of the budget construction funds, the industry norm of this percentage is about 10 percent (Al-Dubaisi, 2000). Merrill (1982) has taken an investigation research on the "Air Force construction Contract Disputes" to identify dispute types and causes of design changes. He found that 48.2 percent of the investigated projects have increased the cost by less than 2 percent due to design changes, 2.0 – 4.9 percent increased on cost for 16.8 percent of the projects, 5.0 – 9.9 percent cost increased for 11.6 percent of the projects, 10.0 – 14.9 percent cost increased for 3.4 percent of the projects and above 15.0 percent cost increased for 20.0 percent of the projects. In a study that carried out by Akinsola et al., (1997) to identify and evaluate the factors that are likely influencing changes on buildings, they have collected data from 46 completed building projects in the UK. They have found that all buildings have encountered design changes and costs have increased to various

32 degrees depending on the size of the investigated projects. The result of this study is shown in Table 2.7.
Table 2.7 : Project Size and Change Measurer (Akinsola et al., 1997)
Project Size
Less than £ Million
% No. of
Projects
30.4
Average
Project Cost
(Millions)
0.50
Cost of
Changes
(£1000)
341
Cost
Increase Due to Change
68.2%
£
£
£
1 – £ 5 Millions
5 – £ 15 Millions
15 – £ 25 Millions
17.4
39.2
6.5
1.68
8.89
25.50
101
1261
2317
6.02%
14.18%
9.09%
£ 25 – £ 50 Millions 2.2 46.10 1566 3.40%
Over £ 50 Millions 4.3 93.25 8500 9.11%
CII publication 6-10 (1990) carried out a study on the impact of changes on construction cost and schedule. According to this report, changes made during construction may result in cost increase due to some combination of the following:
ƒ Loss of labour productivity due to interruption of work and loss of motivation to re-do the work;
ƒ
Delay caused by the possibility of unavailability of material, tools and construction equipments at site that are required to execute the changes if these items are not the same as that needed for the original work. In many cases there is also time lost between receiving the instruction to put on hold the work under changes and waiting for new instruction to come;
ƒ Extra timing, labour and equipments are required to demolish and remove the existing work;

33
ƒ Chances of material waste due to re-work operation which should be compensated by the owner;
ƒ
Non-productivity period during redirection of the work that result from shifting labours, materials and equipments to perform different tasks; and
ƒ Need of recover the schedule by means of overtime or multiple shifts to maintain the original program
Weston (1991) reported three levels of effects caused by design changes.
These are: (1) an increase in time to do the changes; (2) an increase in both time and cost; (3) an increase in time and/or cost of other activities. He further added that changes also lead to loss of momentum, efficiency and extra cost to cover up the administration work.
Burati et al., (1992) presented a quantitative analysis of changes and their associated cost. In this study, 9 industrial projects of at least USD500,000 in total cost were selected. The result showed that design changes amounted to average of
12.4 percent of the total cost of the project. Similar study was conducted by Zietoun
(1993). In this study, 5.3 percent was the median accumulative increase on cost and 9 percent increase on schedule. Chang (2002) identified the reasons behind increasing the consultancy design cost through his investigation of four case project documents in Taiwan. He reported that the engineering consultancy cost increased on an average of 24.8 percent based on the four sampled projects.
Love et al., (2002) presented a case study on a project consisted of two sixstory residential apartment blocks, containing a total of 43 units with many facilities around the blocks. The investigated project is located in Australia. Interviews were primarily used to determine the causes of changes and their associated cost. Direct observations and documentary sources provided by the contractor, consultants, subcontractor and suppliers were also used to derive the data. The main finding of this case study is shown in Table 2.8.

34
Table 2.8 : Causes and Cost of Changes (Love et al., 2002)
Cause
Design Changes
Design Errors
Design Omissions
Construction Changes
Construction Errors
No. of
Events
65
12
2
14
120
Non-
Productive
Time (Days)
20
13
7
2
14
Cost of
Changes
(A$)
182,893
59,233
6,837
72,979
19,514
% of
Contract
Value
1.67
0.55
0.06
0.66
0.17
Construction Omissions 2 - 760 0.006
Construction Damages 3 14 3,288 0.03
69 3.15
2.6.2 Impact of Design Change on Time
Delays are identified as the principal factor leading to the high cost of construction (Zaki and James, 1987; Charles and Andrew, 1990; Kartam, 1999).
Design changes are one of the major cause that lead to such construction delays.
Example is the work that was carried out by Arditi et al., (1985) in their study to identify the reasons for delays in public projects in Turkey. They have found that
3.54 percent of the delays were caused by design changes. Their study was based on responses to questionnaires received from 44 public organizations and 34 contractors. Similar effort was carried out by Sullivan and Harris (1986) to determine the most likely causes of delays on large construction projects in the UK.
This study was conducted through interviews and responses to questionnaire survey conducted on 3 construction clients, 4 consultants and 13 top UK contractors. The result of this study indicates that 49 percent of the delays are caused by factors related to design changes. In Nigeria, this percentage is reported to be 71 percent
(Okpala and Aniekwu, 1988). The result of this study was drawn from responses to

35 questionnaires in which responses were received from 58 engineers, 52 architects and 46 quantity surveyors in three cities in southwest Nigeria.
Chan and Kumaraswamy (1995) have surveyed sample of 111 construction projects in Hong Kong and found that changes in general to be the commonest and principal sources of time overruns. Furthermore, client-oriented changes when introduced mid-stream during the construction period, causes excessive delays to projects compared to the ones that introduced at earlier stage. Ogunlana et al.,
(1996) conducted a study in 12 high-rise buildings construction projects in Bangkok,
Thailand to identify the causes of delays. The result of this study showed that design changes were one of the main causes of delay and they were also created design and co-ordination problems for field staff. They have added that, owners request for changes are usually made at short notice, thereby impacting contractor’s plans. In addition, some changes were large in magnitude in which extensive redesign were necessary. Al-Momani (2000) has investigated the causes of delays on 130 public projects in Jordan. Projects investigated in this study included residential offices and administration buildings, school buildings, medical centers and communication facilities. The result of this study indicates that the second top rank for causes of delays was the design changes (15.4 percent).
Another study in the impact of design changes was carried out by Hanna et al., (1999). Data from 61 construction projects were collected to develop a statistical model that estimates the actual amount of labor efficiency lost due to design changes.
They have illustrated in this study graphically the impact of design changes on time as shown in Figure 2.2.

36
Figure 2.2 : Planned and Actual Loading Curves (Hanna et al., 1999)
Referring to this figure, the planned and actual loading curves indicate that a project is considered impacted by changes when the actual and planned cumulative work hours vary substantially. The actual loading curve can take two forms. One form is a loading curve without time extension and the other one is a loading curve with time extension. It can be seen from the figure that the impact of the design changes leads to extension of time beyond the originally planned duration. The magnitude of the time extension is proportional to the time of executing the changes.
Hence, changes at later stages tend to cause more disruption on the original planned schedule compared to the ones that are released at earlier stage.
2.6.3 Impact of Design Change on Productivity
Productivity is an important issue in any organization, although it has received limited attention in architectural and engineering organizations (Thomas et al., 1999). It might be defined as the quantity of work produced per man-hour, equipment hour or crew hour (Finke, 1998). Lost of productivity is a classic result of

37 disruption caused by design changes, because in the end more working- hours will be required to do the same work (Meyers, 1994). To this extent, any disruption on the expected productivity outcome for any given part of the work in a project, either at the design level or at the construction stage, will increase the original planned working-hours cost which in turn increase the overall cost of the project. It has been reported that design change is a major cause that lead to loss in productivity.
Consequently, to obtain a fair compensation at later stage due to loss of productivity associated with design changes, it is important to identify the changes when they occur and accurately predict and quantify their disruptive effects on unchanged work.
Such procedure will give better estimation of expected cost of the newly introduced changes. It has been argued that productivity problems are compounded on large industrial projects by many design changes or revisions that are frequently characteristic of complex projects (Borcherding, 1976). This article went further to state that when changes are expensive and unexpected or demand arises to expedite or reschedule the completion of certain phases of the work, productivity loss occurs.
Leonard (1987) described in his quantification investigation of the effects of changes on labour productivity. The study was based on the detailed review of 90 claim cases, each from a separate contract. The cases were divided into two groups namely civil/architectural and mechanical/electrical. In this paper, the percentage loss of productivity was shown as a function of the percentage of the total work hours spent on changes. The result of this investigation shows that a four or five percent increase in the work hours spent on changes lead to 10-20 percent loss of productivity. Moselhi et al., (1991) showed that there was a cumulative effect on productivity when the time taken to do the changes is more than 10 percent of the planned contract time. They are also illustrated that for 10 to 60 percent of total contract timing spent for executing the changes, there is loss in productivity between
10 to 30 percent.
The University of California, Berkeley completed an earlier research project that published " Construction Changes and Change Orders: Their Magnitude and
Impact " (Hester et al., , 1991). This research focuses on identifying the impacts of the changes on labour productivity at the craft level. It indicates that even a small number of changes, two or three, has a significant negative impact on labor

38 productivity. Thomas and Napolitan (1995) have carried out an investigation on quantitative effects of construction changes on labor productivity. Their data for the analysis were based on daily productivity values from three industrial projects covering a period within 1989-1992. A total of 522 workdays of data were collected.
The results show that the average effect of all changes was 30 percent loss of productivity. Investigations into the cause of productivity losses showed that there were disruptions when changes work was performed. The regression analysis in this study showed a 25-50 percent loss in productivity of the work depending on the type of disruption. The relation between the disruption type and the resulted efficiency is summarized in Table 2.9. It can be seen from the table that lack of material lead to a drop on efficiency by 26 percent. Out of sequence work and non-availability information constitute a major cause of efficiency losses.
Table 2.9
: Quantitative Effect of Disruptions
(Thomas and Napolitan, 1995)
Disruption type Efficiency
Material availability
Tool availability
Equipment availability
Information availability
Sequencing
0.74
1.06
1.05
0.53
0.71
CII publication 43-1 (1994) clearly shows that projects with a high degree of change experience lower productivity. The relation between the percentage of changes and productivity at engineering and construction phased based on this study is shown in Figure 2.3 bellow.

39
Figure 2.3 : Effects of change within phases. (CII publication 43-1 1994)
CII publication 43-2 (1995) investigated the impact of changes on labor productivity during design and construction. In their statistical approach, they have illustrated graphically the relationship between the amounts of changes percentage wise versus productivity. Figure 2.4 shows the percent of construction changes as a function of construction productivity, while Figure 2.5 illustrates the relation between the design changes versus design productivity.
Figure 2.4 : Construction Change and Construction Productivity
(CII Publication 43-2, 1995)

40
Figure 2.5 : Design Change and Design Productivity (CII Publication 43-2, 1995)
Both the above figures exhibit a similar downward trend in productivity with greater amount of changes. Figure 2.4 shows the mean productivity regression line crosses the unity at 6 percent construction change. This means that better construction productivity could be achieved if construction changes are less than 6 percent. Productivity then decreases with increase number of changes. At 35 percent construction changes, as an example, lead to 10 percent loss in construction productivity. Productivity regression line on Figure 2.5, on the other hand, does not cross the unity in the population of projects under this study. This is an indication that it was not possible to complete the original design scope as planned even without any changes. In addition, less productivity is most likely encountered in the engineering phase than in construction. Comparing to loss in construction productivity at 35 percent changes, engineering productivity might be as less as 17 percent.

41
Ibbs et al., (1995) and Ibbs (1997) carried out an investigation to quantify the nature and impact of project changes during detailed design and construction. Data were collected by means of a questionnaire. Responses were obtained from 35 different organizations, representing 104 projects. The findings of his work showed that the amount of design changes negatively affects the design productivity. For example, the productivity of the design in these investigations show that there is 16 percent lost in design productivity when there is 40 percent change on the project.
2.7 Development for Improving the Management of Design Changes
The management of the design and construction are complex enough without changes, yet it is a familiar characteristic for the projects. A survey of the literature suggests that researchers have focused their attention on addressing the management of the construction phase more than the management of the engineering phase of a project (Eldin, 1991). He added, the reason behind this is perhaps the cost associated with the engineering phase which is only 3-10 percent of the total project cost.
Design changes are inevitable in any building projects and frequently lead to disputes between the concerned parties. Management of design changes is an important tool to reduce the risk of disputes that may arises at later stages. If the design changes are not properly managed, design conflict will be created which will result in more expensive design or even failure in the design-construction process. Thus, project managers should react appropriately to the changes and understand how it can influence the behaviour of the project system. Only then can changes be managed effectively.
The issue of managing design changes has not been given much attention in spite of its great important in engineering design practice. The construction industry is still exploring several opportunities in an attempt to achieve a team spirit across the various disciplines involved in a building design office and hence to reduce the level of design changes that being negatively impacting the construction process.
The industry is also at the exploratory stage on how to organize the flow of the design information and how to improve the co-ordination process so that unnecessary

42 design changes can be minimized. Few research works are available on design management, exchange of design information and management of design changes.
There is general trend in the engineering design industry that manual procedure of communicating design changes and design information between design members needs to be reviewed. With the dynamic nature of the design process and the fact of frequently introduced design changes, these manual practices lead to inefficiencies in the design that affect the overall quality of the construction works
(Teicholz and Fischer, 1994; Mooney 1995). The construction process typically involves several disciplines, e.g. architects, structural engineers, building services engineers, quantity surveyors, contractors, sub-contractors, material suppliers etc., collaborating for relatively short periods in the design and construction of a facility.
Until fairly recently, these disciplines tend to work independently, while making decisions that affect the others (Anumba, 2000). Creating a design in a team requires constructing a shared understanding within the team. This shared understanding is the desired result of the team members thus relating the essential topics within the design task and making the necessary decisions (Valkenburg, 1998).
The recent developments in information and communication technology have provided an opportunity to increase the level of integration among different design and construction processes by improving the flow of information. Hence, there is a tendency those days among professionals in the building design and construction process to investigate the practicality of using computer supported communication and collaborative design to develop better methods of managing design changes rather than the traditional manual methods. Thus, no information would be lost in transfer of project data (Kolarevic et al.,, 2000).
Peltonen et al.,, (1993) have taken an advantage of recent advances in information technology and computer collaboration tools to improve design coordination and increase the efficiency for managing design changes. They have proposed an engineering document management system (EDMS) that incorporated document approval and release procedures. Spooner and Hardwick (1993) developed a system with rules for co-ordinating concurrent changes and for identifying and resolving conflicting modifications. Ganeshan et al.,, (1994)

43 developed a system to capture the history of the design decision-making process, initiate backtracking, and determine the decisions that might be affected when changes are made in the design of residential buildings. Krishnamurthy and Law
(1995) presented a change management model that supports multidisciplinary collaborative design environments. They have proposed three-layered model versions, assemblies and configuration. The model monitors independent design activities by systematically tracking components descriptions in individual disciplines. It achieves co-ordination through un-matched communication of design changes. Rezgui and Depras (1995) have developed an approach to tackle the problem of integrity and consistency in construction documents production and management. This approach is based on building a construction project reference model and document reference model. Both models are linked with an association model that indexes building components to documentary items.
Another approach for managing design changes was proposed by Mokhtar
(1998a). He has provided a thorough analysis of the production process of construction technical documents with an emphasis on techniques for co-ordinating design information so as to accommodate design changes. The analysis diagnoses the main problems that cause incompatibilities in design information. These problems are the management of design changes, the media used to communicate design information, and the source of final documents. The model is capable of propagating design changes and tracking past changes. Hegazy et al., (2001) presented an information model to store design information, record design rationale, and manage design changes. The proposed model incorporates a central building components library (BCL) that is used to create a complete building project hierarchy (BPH). The original aspect of the proposed BPH is its representation of multi-disciplinary design data within each building space. In addition, each building component in the model has preset communication paths that help to automatically communicate changes made to any component to all affected parties. All of these models, however, are conceptual in nature and need further development to be practically implemented.

44
Co-ordination of design information during the design-construction activity is essential for the design team to provide quality design technical documents that are free of incompatibility errors (Pena-Mora et al., 1995). In this regard, exchange of the design information between the designers has been investigated by Vries and
Somers (1995) who developed a process model for that purpose. They suggested that a protocol to exchange information should ensure that both senders and receivers of information interpret it the same way. Also all the required and correct information should be exchanged. Abou-zeid et al., (1995) have proposed shareddata resources as primary component for common communication channels to exchange data between participants in a project. Mokhtar et al., (1998b) have presented an information model for managing design changes in a collaborative environment. The idea of their work was based on building a single reference source of information for all active design components and assigns it a responsibility to distribute the design changes to all concerned design members.
Pocock et al., (1997) found that projects with greater interaction between the project personnel performed better with respect to cost, schedule, changes and design deficiencies (based on a study of over 200 completed projects). Baldwin et al.,
(1999) added that by a better understanding of the flow of information among project participants, the design may be improved and hence chances for design errors may be reduced which, in turn, reduce the chances for design modifications. Baldwin also found that non-existent or ineffective design management may also produce conflicting construction details that result in delays and problems during construction. Austin et al., (2000) established the importance of effective design management to produce a co-ordinated design of less conflict and to ensure the smooth running of information that both reduce the chances of unnecessary design changes. Their research proposed a planning methodology based upon information requirements to optimize the design process. Kuprenas, (2003) specifically examined the impact of the number of meetings toward the successful design. He found that frequency of design team meetings and frequency of reporting of design phase progress were found to reduce the design deficiency and hence design changes.

45
Soh and Wang, (2000) have established parametric co-ordinator to manage design changes between geometric models. Their proposed co-ordinator is based on the knowledge-based constraint solver and attempts to manage the constraint models using the built-in linking knowledge to ensure consistency of design changes. While the principle of this technique is simple, its practical use requires intensive input data which might be beyond the normal engineering practice. Zaneldin et al., (2001) have developed a collaborative system for design co-ordination and effective management of design changes in building projects. Their proposed system is conceptual in nature and once it developed further, it might be helpful to store building data, record design rationale, manage multidisciplinary design changes and share design information. Further investigation has been conducted by Hew et al., (2001) in which knowledge-based engineering (KBE) has been used to improve the level of design management and the co-ordination process among the different disciplines.
2.8 Chapter Summary
1. The objective of this chapter was to establish the boundary of the existing knowledge that are in relation with design changes and to provide up to date the necessary background from the previous studies on the main topics associated with the design changes so that it sets a sound foundation and provides a platform for expanding the knowledge within the investigated subject. The above objective has been accomplished through identifying the main issues that are related to design changes and are namely: (i) definitions of design change; (ii) their classifications;
(iii) their sources; (iv) their causes; (v) their impacts on the construction industry as well as (vi) on going development for managing the design changes.
2. Design change has been defined in its simple term to be any addition, omission or modification to the existing scope of work that affect the original cost and/or the original programme. Different classifications have been identified in this chapter as means of defining the design changes depending on their nature, effect and occurrence in the life cycle of the projects. These classifications include the "formal changes" which can be identified before they come in effect and the "informal

46 changes" which can be identified only after the facts and normally based on unexpected events. "Direct, constructive and cardinal changes" are other documented classifications for design changes. In "Direct changes", the owner directs the consultant or the contractor to do works that are not specified in the original contract, while the "constructive changes" are the ones that result of problems for which the owner is responsible and finally, "cardinal change" are the changes that result from carrying out substantial amount of works out side the scope of the original contract and lead to a significant deviation from the original contract scope and time.
Examples for each type of classification have been given in the chapter for clarifications and for easy understanding of the terms.
3. The sources of design change have been identified in the chapter. It was found without exceptions that clients, design members, contractors, suppliers and local/planning authorities all originate design changes. While clients commonly introduce changes as a result of changing their original requirements or due to financial reason, design members normally originate design changes to rectify their design mistakes or due to inconsistent in the construction drawings and/or specification. On the other hand, contractors tend to modify the original design to adopt alternative construction methods that of more familiarity to them or to simplify the construction process to save time and/or money. Suppliers have been reported to be least originators of changes. In such cases, changes become necessary to be able to use their specific material. There are cases where local/planning authorities introduce changes as part of new regulations.
4. The causes of design changes have been presented in the chapter. The most common causes of design change as revealed by the literature review include changes on the original requirement due to various reasons, design deficiency, lack of proper design briefing, incomplete design at the tender stage, communication problems, co-ordination problems, conflict in the design documents, unexpected site conditions and the introduction of the new government regulation.
5. The impacts of design change that influence the outcome of a project have been discussed in details. It was reported that design changes normally increase the original contract cost, lead to extension of time and result on loss of productivity.

47
There is also an indication in the literature review that changes made at later stages tend to cause more disruptions on projects compared to the ones that are released at earlier stages. Clients, consulting engineers and contractors all have become increasingly worried about these negative impacts associated with the design changes which may lead to expensive claims and/or dispute.
6. The chapter discusses up to date the on-going development to manage the design changes. In this regards, the proposed methods have used the computers in the collaborative design environment with an intention to provide better tools to manage the design changes. It was found that the identified methods are not equally exclusive but rather, share common features. All approaches use data as the means to exchange information among participants. None of the reported approaches appears suitable to provide remedy for all the problems associated with the management of design changes.
7. The chapter highlighted the existing research on the issues of the design changes in particular sources, causes and impacts of design changes. However, there was no attempt found in the literature deals with the fee assessment associated with the design changes. This gives a scarcity in the subject which needs to be addressed here in this research.

CHAPTER 3
THE PRINCIPLE OF CONSULTING ENGINEERING PRACTICE
3.1 Introduction
This chapter explores the results of the literature searching in the area of consulting engineering practice which considers an essential to the main issue of this research work. A comprehensive background is presented in the chapter to provide in-depth understanding on the services that normally provided by the consulting engineering firms and on the methods of charging for their professional services to the clients.
The chapter starts with general definitions of the client and the consulting engineering firms. The reasons for engineering services are presented followed by the criteria for selecting the consulting engineers and the process of their selection.
Previous researches have identified the obligations of both consultants and clients which are highlighted in this chapter as well as general review on the services that normally provided by the consulting engineers at various stages of the life cycle of the projects . The methods of charging for the professional services as identified in previous research works are presented in detail at the end of this chapter.

49
3.2 Definition of the Client
A Client is a person or organization that hires a consulting engineering firm to solve an engineering problem or to perform an engineering service, Cohen (1982).
The client might be either a government or a private sector represented by one or more persons or by a department who is fully authorized to manage a given project and to engage, if necessary, a consulting engineering firm to carry out a specific task within a specific time and cost. Demkin (2002) defined the client to be someone responsible for some or all aspects of facility planning, design, construction and operation who has the ability and capacity to act and decide on matters of his scope.
He further added that a client may represent a corporation or an institution and might be delegated to lead or represent a group of people – a board of directors, for example, or a building committee. A client might have a technical or non-technical background. A technical client is the one with engineering experience and knowledge such as the ones who come from engineering firms while non-technical client is the one without engineering knowledge such those with financial, commercial or managerial backgrounds.
3.3 Definition of the Consulting Engineer
Williams and Sally (1994) defined the consulting as the process in which a consultant provides a service to a client for the purpose of meeting the client's need.
Biech (1999) defined the consulting to be the process by which an individual or a firm assists a client to achieve a stated outcome. In specific term, Consulting engineering firms are independent professional firms who provide professional engineering services for clients on a fee basis (Stanley, 1982). They are independent organizations in a legal sense because they manage and operate their own business and their service is based on independent contracts. Consulting engineering firms may be owned by an individuals, partnerships or corporations. The size of the consulting engineering firms vary from a single office operates with few technical staff involving on a particular field of engineering such as in the design and

50 supervision of local residential houses to large scale firms operate from many local or international branches with hundreds or probably thousands of specialized technical staff who provide multidisciplinary services such as environmental, planning, architectural, structural, mechanical and electrical services working on major projects including commercial and residential complexes, high rise buildings, bridges, highways, electricity plants, airports, dams and harbours.
3.4 Reasons for Consulting Engineering Services
Clients need to hire consulting engineering firms for variety of reasons. Gil et al., (1983), and Cockman et al., (1992) produced many of them including the lack of expertise, lack of experience, lack of time, for economy and quality reasons, desire for neutral opinion, seeking new ideas, desire to give to or share responsibility with outside consulting firm, requirement of some funding agencies and in many cases due to regulations of insurance companies.
Many governmental agencies, private sectors or individuals have no engineering capacity of their own therefore they turn to the consultants to do their engineering work or to solve their technical-related matters. If the occurrence of this type of work is rare in the organization, it would make no sense to establish its own engineering office when it is most likely more economical and easy to obtain a consulting engineering firm to do the task as required. There are as well cases where clients involve either fully or partially in an engineering work in their organization. Frequently, these clients will have their own engineering department which is possibly sized for normal and most frequent work. The staff in this case might not be well qualified to carry out certain type of works that require a high skill of knowledge or very specialised in nature which in turn necessitate the need for consulting firm (Hoon, 1979).
Furthermore, there are situations where both knowledge and experience are available in the organization that would be capable of undertaking a new assignment but the staff may not have the time to take extra load (Gil et al., 1983; Daft, 1986).

51
It might be more appropriate and economical to give the new work to the consultant engineering firm rather than attempt to increase the number of staff to handle the peak work load. Economical and quality reasons in many circumstances are essential to all clients whether a government, private or individual to accomplish their engineering works in the most economical way and to get as a value of their money best quality and reliable design in a shortest possible time. These are the clients' main focus points and normally the consulting engineering firms are well aware of these issues. Hence, the consultants spend a great effort to meet these requirements since it is the only way to keep good relation with the clients and to ensure to get invitation when new works come in the future.
In situations where disputes may arise due to incorrect design caused by another consultant or due to faulty construction work caused by a contractor, clients tend to engage independent consulting engineers to investigate the cause of the problems in order to obtain the opinion of an acknowledged expert not directly associated with any of the sides and to use the independent consultant to act as an expert witness to support clients' cases. Seeking new ideas and approaches are common reason among clients in their decision to hire consulting engineering firms in assumption that the consultants look at the problems in fresh perspective way, bring with them new ideas and different approaches from other firms (Ling et al.,
1997). Sharing the experience of the consultant no doubt will enhance the knowledge of the owners' in house existing staff which in turn will have a positive effect to the client in long run. Many clients also have a desire to have engineering responsibility shared with or carried out by an outside consultant. Common situations to this approach is for projects of high rise risks such as offshore structure, dams, long span bridges crossing water and high rise buildings founded in weak soils.
Finally, banks or other agencies funding projects may require the design to be carried out or checked by an independent and approved consulting engineer as part of their regulation, condition and loan agreement as well as regulations of some insurance companies in which do not provide design liability insurance to clients who design their own projects (Cockman et al., 1992). The reason for this being that in case of claims due to design mistakes, the consultant (the owner) can not be

52 against him. If the owner needs to cover the risk of the design errors, this may lead to the necessity of appointing an outside consultant and request for the necessary design liability insurance.
3.5 Services Provided by a Consulting Engineer
Projects vary in scale and complexity as in urgency and duration.
Independent of the nature of each project, most of them pass through a cycle of work as indicated in Figure 3.1 in which the consulting engineers commonly involve.
Feasibility
Study
Preliminary
Design
Detailed
Design
Operation
Phase
Supervision
Stage Tender Stage
Figure 3.1
: Stages in Projects’ Design Cycle.
The involvement of the consulting engineer at each stage varies depends on the nature and requirement of each project and the time of his assignment on the project. While the above figure shows a typical sequence of the work to be carried out by the consulting engineer, it is not always possible to complete one stage before the next one. In many situations some activities do overlap especially at the case where the project is an urgent one. American Society of Civil Engineers, Manual reports on Engineering practice No. 45 (1988) highlights six phases where the consulting engineer usually involve. These phases are feasibility study phase, preliminary phase, detailed phase, tender phase, supervision phase and operation and manual phase.

53
3.5.1 Feasibility Study Phase
In any project it is essential to evaluate the initial proposal of the client by qualified people to determine its feasibility. At this phase, the consulting engineer usually makes an analysis of the client's needs, provide conceptual design, alternative options and approximate budget estimate as well as to evaluate the workability and suitability of the options and highlighting the advantages and disadvantages of each alternative. At this stage the consulting engineer should advice the client on any technical difficulties that may arise at later time in order to decide on the best way to proceed with the work.
3.5.2 Preliminary Design Phase.
The American Society of Civil Engineers, Manual and Report on Engineering
Practice No. 45, (1988) outlined number of services that the consulting engineer normally provides at this stage. These services include reviewing the feasibility study reports, clarifying and defining the project basic requirements, reviewing available data, discussing general scheduling, advising the client on any additional data or services required to be carried out along with preparing preliminary design documents consisting of final design criteria, preliminary drawings, outline specifications and written descriptions of the project.
The structural engineer should advise at this stage on any requirement for further investigations such as geotechnical, hydrological, and environmental studies and topographical survey. The structural engineer shall evaluate and interpolate the results of these studies when they become available and draw a conclusion of the findings as to advise the client accordingly. Further services may be required to cover other aspects such as the study of user requirements to determine and confirm the function, space and the engineering principles of the proposed work, site conditions, basic requirement of planning and design together with an initial overview of the budget estimate proposed by the client. This phase should include as well the determination of the construction material, construction methods applicable to each part, and type and size of the main structural elements. Furthermore, any

54 protection measures required for durability such as cathodic protection or protective coatings to minimize the risk of chloride and carbonation attacks or tanking system against sulphate in the soil shall be discussed and agreed with the client.
3.5.3 Detailed Design Phase
This phase is usually undertaken only after the client has approved the preliminary design scheme and information. The basic services of the consulting engineer at the detailed design phase include the production of construction drawings, writing the specifications, assisting or writing the Bill of Quantities and assisting or preparing the tender documents. The structural engineer shall also provide the necessary documents that required to apply for any regulatory permits for his design or for the start of the construction work.
3.5.4 Tender Stage
Once the design is completed in form of proper plans, sections, specifications and details, the consulting engineer normally prepares complete sets of tender documents and the wok might proceeds to tender invitation phase. The consulting engineer usually assists the client in developing a tender list of suitable and qualified contractors for carrying out the proposed work and assists in preparing the contract documents and tender invitation process. Once the tender is out, the consulting engineer shall answer or clarify within reasonable time all technical issues or quarries related to his part that the bidders may have. The consultant shall also involve and participate in any mid-tender meetings or discussions to be held with the bidders wherever necessary. The consultant shall record his answers and to take notes to all the points that might arise from such meetings or discussions for later actions or corrective measures.

55
Upon the receipt of the proposals from the contractors, the consulting engineer analyzes the proposals, determining their compliance with the tender documents and specifications and advises the client as to the workability and acceptability of any alternative materials, methods or details proposed by the contractors in their submissions. The consultant may also participates in negations with bidders to clarify proposals or reduce the bid price. After the comprehensive evaluation of the bids, the consulting engineer should advise the client of his recommendation on the most competitive bid. Once the contract is awarded, the consulting engineer should provide to the selected contractor full set of working drawings with any relevant details and reports to enable him to start mobilization for the work. A pre-start meeting is normally required to introduce the key team members of both the client's and contractor's sides and to set up procedure for carrying out the work and for the communication between both sides.
3.5.5 Supervision Phase
Site supervision is best provided by the firm who was involving in the design phase of a project because of his familiarity with the work. To this extend the consulting engineer may be required to provide part or full-time on site supervision for some or full duration of the construction work. The provision for supervision better to be included in the design contract or might be added to the existing scope of work at later stage under separate agreement. The required level of site supervision depends on many factors including the size, complexity and nature of the work as well as the client's requirements. Site supervision is normally carried out by a highly qualified resident engineer who should have sensible character and well developed ability to work with people and to enforce the contract requirements equitably against contractor and client. He must be more than a competent construction man because he stands between client and contractor, Cohen (1984).
General publications such as the one by The Institute of Civil Engineers
(1996) and the Association of Consulting Engineers Malaysia (1998) outlined the most common professional services normally provided by the consultant. These

56 include working at construction site to assure that the project design is correctly interpreted by the contractor and the quality of the work is acceptable, reviewing and approving the detailed construction programme of works as proposed by the contractor. In particular, the consulting engineer shall note the dates for any outstanding information, drawings or decisions required from the client or the consultant and shall ensure compliance with the same so as to maintain the programme of the project completion time.
The consulting engineer shall prepare any further plans, drawings, design and schedules necessary for carrying out the works as well examining and approving the materials to be used, working drawings, construction methods and method statements in relation to his design. In addition he should make the necessary arrangements for the inspection and testing during the manufacture and installation of materials and plant wherever required to be inspected or tested and supervising the tests that carried out at site. He should as well make the necessary site visits to satisfy himself that the activities are executed generally according to the contract and otherwise in accordance with good engineering practice.
Furthermore, the consulting engineer shall clarify and answer queries, provide missing information, review and revise drawings, attend progress meetings, issue progress reports and co-ordinate with other contractors, sub-contractors or suppliers wherever applicable as well as examine and approve the details of materials or services that included in the contract within provisional sums and assist in settling disputes or differences that may arise between the client and the contractor.
3.5.6 Operation Phase
At the completion of the construction phase, the consulting engineer is required to assist in the start-up of a project operation. The consultant at this stage is required to test, inspect and check the integrity of the design and contractors' work under operation condition and report the findings for corrective measures, if any.
Although the project is under operating condition, the consulting engineer prepares a

57
"snack list" on any defects or minor works that need to be carried out by the contractor. The consultant should follow up these requirements to ensure a proper execution.
Furthermore, the consulting engineer prepares in co-ordination with the contractor number of "As Built" drawings as specified in the contract documents in both hard copy and those days in digital format. The "As Built" drawings should reflect in all aspects the actual construction details and specification. The consultant also requires to hand over to the client any operation and maintenance manuals either from him or from the contractor. Any assistant or input requires at later stage from the consulting engineer to assess or settle down the final account, such assistant shall be provided. If defects occur during the maintenance period due to the consultant's design, he shall act properly within reasonable time to investigate the cause and to rectify the situation in relation to his work.
3.6 Methods of Charging for Consulting Services
Fees for consulting services are determined by various methods depending on the nature and extend of the work, its complexity, duration and the service required by the client. Each method is more applicable in certain areas than others.
Therefore, it is necessary to have various methods of charging for consulting services to cover all aspects of the works. There are six methods that have been identified from the literature search including the work by Kumarasivam (1979), Stanley
(1982), Hurley and Touran (2002). These methods are:
•
Lump Sum Method;
•
Salary Cost Times Multiplier Plus Non-Salary Cost Method;
•
Cost Plus Fixed Amount Method;
•
Per Diem Method;
•
Percentage of Construction Cost; and
•
Retainer Method

58
3.6.1 Lump Sum Method
In the lump sum method, also known fixed price method, a consulting engineer performs his professional services to a client based on a fixed amount of money independents of time it takes to do the work or construction cost. This method is more applicable for works relate to special studies, reports and investigations where scope of services is well defined. The method might be used as well for small to moderate size and complexity projects when the client desires to know at early stage the final amount of money to be paid to the consulting engineer.
The lump sum amount can be calculated as a total cost of the following four items
(Stanley, 1982):
1. Direct salary cost plus up to 26 percent of the direct salary cost for profit allowance. This includes salaries of all technical and non-technical staff assigned directly to the work. The cost of staff that not fully assigned to the work is to be added proportionally according to their involvement.
2. Direct non-salary cost plus up to 7 percent of the direct non-salary cost for profit allowance. This includes the cost of everything allocated to the work excluding salaries of staff. Examples are expenses of equipments, stationary, software, special insurance, liability insurance that are directly needed and assigned for the work.
3. Indirect cost plus up to 18 percent of the indirect cost for profit allowance. This is the cost of items or salaries not specifically assigned to the work. It is a common or a shared cost to run the office. Rents, facility bills, office maintenance, secretaries, administrative, accounting and clerical salaries are few examples of the indirect cost.
4. Sub-contracts cost, if any, plus between 4-8 percent profit allowance. This covers the cost of services included in the scope of work but outside the speciality of the consultant himself which in turns required to be performed by another consultant in a subcontract agreement. These may include the cost of geotechnical investigation, site surveying, modelling, and perspectives etc.

59
3.6.2 Salary Cost Times Multiplier Plus Non-Salary Cost Method
The cost of consulting engineering services on the basis of salary cost times multiplier plus non-salary cost is a common method that used by consulting engineers. Salary cost is defined as a direct salary plus profit allowance and nonsalary cost is defined as direct non-salary cost plus profit allowance, both terms and allowances are defined in the above section, items 1 and 2 respectively.
The multiplier is a factor which compensates the consulting engineer for his overhead profit. It takes account of various items including, but not limited to, all office expenses such as cost of facilities, office stationary, drafting equipments, engineering instruments and automobiles as well as property insurance, governmental taxes and documents' renewal charges.
The multiplier also considers salaries for executives, managerial, accounting, clerical, partners and principals beside provision for loss of productive time of the staff and so on.
The size of the multiplier depends on many factors including the set-up level of the office, cost of the rent, office running cost and the level of facilities provided to the staff as well as nature of the work, experience and relation of the consulting engineer with the client, competition, and desire of getting new assignment. In
United States, the median multiplier was between 2.2-2.5 in 1985 (American society of Civil Engineers, 1988). Higher multiplier may be used for projects of short duration or small size or for more specialised work.
3.6.3 Cost Plus Fixed Amount Method
Under a cost plus fixed amount method, the consulting engineer gets paid the actual cost he spends on a project in addition to a fixed amount of money normally a percentage of design fees. In this method, the actual cost consists of all staff salaries involve in the project, cost of all services and supplies either directly or non-directly as defined in the previous sections. The purpose of the fixed amount is to compensate the consulting engineer for his net overhead profit. This method is more

60 effective at situations where scope of work is not clearly defined at the tender stage or there is a great chance to increase the scope of work at later time after the contract is signed in such situation that gives difficulties to assess the cost of the professional service at early stage due to these uncertainties.
The advantage of using this method is that both client and consulting engineer get fair deal since client pays the actual amount for the services he is getting and there is no risk on loss to the consulting engineer with reasonable and predefined overhead profit. In addition, the method covers the cost of design changes at any stage during the life cycle of a project which in turn reduces the chance of disputes in the assessment of cost design changes. However there are many disadvantages on this method. The consulting engineer has to justify and back up his claims to the client. This means that the consultant is most likely to spend great time organising the paper work, recording and detailing the claims to be acceptable to the client. This administration work of coarse needs an effective management system and possibly more staff for this purpose. Also, both client and consulting engineer do not know in advance the cost of the contract for the proposed work which might be needed for procurement and planning reasons. Nevertheless, to have this method works it requires good understanding, trust and co-operation between the client and the consultant in addition to good management system to keep good track of the work. An early agreement on the schedule of payment is essential and advisable to be in short intervals as in monthly basis for easy evaluation.
3.6.4 Per Diem Method
In this method, the consulting engineer sets up daily or hourly rates for each staff member and use these rates to bill clients for the time that used by each staff to do the work. The daily rate is based on the total working hours applicable to the consultant's firm which should be mentioned and agreed in the contract. In a daily basis contract, services that are required part of the day shall be reimbursed for full day. The consulting engineer considers many factors in his rates to cover all

61 associated costs in addition to overhead profit. Travel expense and living cost associated with the work shall be charged separately. This method is more appropriate for projects of short durations or special studies, reports and investigations and also might be used for assessment of fee variation related to design changes. The method might be used as well to assess the cost of training, seminars or workshops for client's staff. For large scale projects, the amount of administrative work require to track the time that used to perform the work does not justify its use.
The main advantage of this method if used for short duration works, that are days rather than months, is easy to implement and easy to justify the days and hours.
The client might call the consulting engineer to perform specific tasks in individual cases without formal invitation and tendering process.
3.6.5 Percentage of Construction Cost
Under this system, the fee for professional service is expressed as a percentage of total construction cost. This method is more useful at situations where types of projects, design details, construction material and general finishes are almost identical and well known to both client and consultant such as in schools, social houses and residential accommodations complexes of same types. The method was widely used in the past in which consultants have established some approximate correlations between the construction cost and the design cost that resulted in various curves like the one shown in Figure 3.2 and schedules similar to Table 3.1

62
Figure 3.2
: Median basic fees as a percentage of net construction cost.
(Stanley, 1982)
Since this method depends on past experience of the client and the consulting engineer, its advantage is being that the consultant almost certain to make a reasonable profit and the client knows as well the appropriate amount to be paid for the design. However, responses to questionnaire carried out by American Society of
Civil Engineering, ASCE (1985) indicated that the present relationship between engineering cost and construction costs for wide range of projects is so varied that it is no longer valuable as a guide for determining the consulting engineers' services.

63
Table 3.1 : Converted Building Scale for Structural Works in Buildings Expressed
As A % of Building Cost (Source: Association of Consulting Engineers Malaysia,
1998)
Building Cost in USD$ Civil & Structural Fees
Up to
Exceeding and Up to
Exceeding and Up to
Exceeding and Up to
Exceeding
And Up to
Exceeding
And Up to
Exceeding
And Up to
Exceeding
And Up to
Up to
$250,000
$250,000
$500,000
$500,000
$1,000,000
$1,000,000
$2,500,000
$2,500,000
$7,500,000
$7,500,000
$15,000,000
$15,000,000
$30,000,000
$30,000,000
$60,000,000
$60,000,000
$400 + 4.00% of Building Cost
$750 + 3.8% of Building Cost
$2000 + 3.55% of Building Cost
$7,000 + 3.05 of Building Cost
$16,000 + 2.7 % of Building Cost
$42,000 + 2.35 % of Building Cost
$93,500 + 2.0 % of Building Cost
$135,000 + 1.85 % of Building Cost
$190,000 + 1.75 % of Building Cost
Notes: (i) This scale, which is derived from the Board of Engineers' Gazetted Scale
of Fees for Normal Professional Services, is applicable to structural
works in buildings.
(ii) Building cost is defined below
(iii) The structural work includes structural works of the building and
foundations but excludes all other works outside the building.
In the above table, the Association of Consulting Engineers Malaysia (1998) have defined the building cost that assumed to be the base for the consultancy fees for the design of civil and structural works. These definitions are as follow:

64
Foundation and excavation connected herewith;
All civil and structural works in the building above the foundation;
•
All mechanical and electrical services including mechanical and electrical
plant and equipment installed in and in connection with the building;
•
All architectural works and finishes incorporated in building; and
•
All other items forming an integral part of the building to enable it to function fully and occupied to its intended standard of comfort, convenience, décor and finishes.
3.6.6 Retainer Method
Many clients prefer to have a continuation of technical advice on call from consulting engineers wherever required and agree to pay a fixed amount of money on monthly, annual or one-time basis. This type of agreement and method of payment is called the retainer method. It is a common method for cases where a client has continuing need for second opinions or technical advices in certain situations that a consultant engineer is able to provide. Typical examples are to check design, review specification, provide legal advice, write technical reports and comment in the use of certain material. It is most unlikely to use this method to design complete projects or for intensive investigations. Determination of the size of retainer fees is a matter of judgment based on the nature and extends of the expected service which might be increased if services provided go beyond the stated level.
3.7 Chapter Summary
(1) This chapter discussed issues related to consulting engineering practice . It started with definition of the client as the person or organization that hires the consulting engineer to perform a specific task while the consulting engineer defined as the professional firm that provides professional engineering services for the client on a fee basis.

65
(2) Reasons for consulting engineering services may vary with the nature of the work, clients' objectives and clients' main concerns. The most common reasons as identified in the previous studies are the lack of expertise, lack of experience; lack of time, economy and quality reasons; desire for neutral opinion, desire for new ideas and different approaches; taking or sharing responsibilities with outside consultant firm; and requirement of some funding agencies and possibility of regulation of some insurance companies.
(3) Various methods of charging for consulting engineering services are exist. Six methods have been identified and discussed in detail including their use, their advantages and disadvantages. These are Lump sum method, salary cost times multiplier plus non-salary cost method, cost plus fixed amount method, per diem method, percentage of construction cost method and retainer method. The literature search revealed that each one of these methods is applicable to certain type of work and agreement. A proper understanding and evaluation shall be given to each method before preferring one to others since some limitations and conditions among them exist.
(4) The result of the literature review revealed that still up to date there are no reviews on the methods of assessing the claims associated with design changes available to the professionals in the construction industry. Hence, there is an obvious need for a research such this study to cover the issues of design changes in general and their fee assessment in specific.

CHAPTER 4
THE CONSTRUCTION INDUSTRY IN OMAN
4.1 Introduction
The objective of this chapter is to provide a brief explanation on the construction industry in the Sultanate of Oman aiming to provide the necessary background about the country in which the majority of the data collection has been taken from (the interviews, the questionnaires survey, the case studies and the validation process).
The chapter initially presents general information about the Sultanate of
Oman and provides a brief on the basic Omani economy. Then the chapter traces the development of the construction sector in Oman between the years 1975 to 2005 as well as discussing the engineering consultancy services industry in the country.
Finally this chapter ends up with extracting relative contract clauses from the mostly used Omani standard for the consultancy services. Emphasis on this regard has been given to the methods of assessing the fee of the design changes as perceived by this
Omani standard.

67
4.2 Oman at a Glance
The Sultanate of Oman lies in the extreme south-east corner of the Arabian
Peninsula. It is bordered on the West by Saudi Arabia and the Empty Quarter; on the North by the United Arab Emirates; on the south by Yemen and on the East by the Gulf of Oman and the Arabian Sea (Oman Chamber of Commerce and Industry,
2005). The total area of the Sultanate of Oman is 309,500 square kilometres and it is the second largest country in the Arabian Peninsula. It has a coastal line extending almost 3165 kms from the Strait of Hormuz in the North to the border of the Republic of Yemen, overlooking three seas: the Arabian Gulf, Gulf of Oman and the Arabian Sea (Statistical Year Book - October 2004). The total population of
Oman is 3,001,583 including 577,293 non-nationals. The age structure of the Oman population is 42.6% are 14 years old or less and only 2.5% are 65 years old and over
(Central Intelligent of America (CIA) – The World Factbook – Oman, July 2005 estimation).
4.3 Brief Highlights on Oman Economy
The Oman economy is based on the policy of free economy that encourages fair competition, freedom of markets and price mechanism as main guiding elements of the national economy. Oman accordingly follows a policy of economic diversification and fair distribution of development to a larger section of the society.
Oman is one of the developing countries that has succeeded in achieving, within a very short period of time, a high level of economic growth.
According to "Oman Chamber of Commerce and Industry, 2005", the Gross
Domestic Product (GDP) at the current prices in 2002 was estimated to be USD
20,303.7 million. The crude oil and the natural gas are the major source of Oman's economy. Their share stands at around 78.4% of the Government's gross revenue.
However, their share on (GDP) dived from 41.9% in 1991 to 41.7 in 2002.

68
4.4 The Construction Sector in Oman
The Sultanate of Oman has experienced a massive development construction programme which started from scratch in 1970 when His Majesty Sultan Qaboos Bin
Said has taken over the power in the country. Both the Government and the private sector since that time participated equally in the development process. The construction sector has almost constructed the new infrastructure of the Sultanate, which comprises the paved roads, residential housings, commercial complexes, buildings, bridges, dams, electrical networks, government premises and many other structures.
The construction and building sector in the Sultanate of Oman started with
502 companies in 1975, and this number increased to 2,896 in 1980. It was doubled in 1986 and by the end of 1989 the number of these companies came up to 5,259
(Contractors' Directory, 1991 - Oman Chamber of Commerce and Industry). Today there are 12,754 companies working in the construction industry. Out of this figure, there are 244 construction companies registered in the Sultanate of Oman are being in the excellent grade (top grade for the construction companies); 1301 in the first class; 2125 in the second; 2199 in the third and 6885 construction companies in the fourth grade (Al Husaini, 2005).
The Contractors' Directory, 1991 (The publication of Oman Chamber of
Commerce and Industry) highlighted the shares of the construction industry in the
Omani economy during the years 1976 to 1991. According to this publication, the
Gross Domestic Product (GDP) share of the construction industry in the Sultanate of
Oman was USD 230.1 million in 1976. This figure jumped to USD 376.74 million in 1981 and then to USD 629.72 million in 1985. Due to economic recession in the whole area and the effects of the low prices of the crude oil which resulted into a severe reduction in the government expenditure, the share of the construction sector in the GDP fell down to USD 275.6 million in the year 1989 and it began to recover again in the year 1990 to reach USD 334.88 million. This sector's share in GDP in
1991 was around 2.9% however by 2002 it dropped to 2.1% (USD 435 million). By the year 2003, the figure has reached USD 693.519 million (Statistical Year Book –
October 2004).

69
The construction sector engaged 21% to 30% of foreign workforce in the private sector. The number of workers in the construction firms during the year 1980 was 33,393 and during the year 1981 it was 48,523 out of 160,507, the total number of workers in the private sector. At the end of 1985, the number of workers in the construction sector came up to 67,271 and in 1988 it jumped to 81,228 (Contractors'
Directory, 1991 - Oman Chamber of Commerce and Industry). By the end of 2004, the number of the workforce in the construction industry was 88,947 (Al Husaini,
2005).
The Ministry of National Economy in the Sultanate of Oman is maintaining statistical records on the number of building permits issued for construction during the previous years by sector along with their associated construction cost and type of buildings. Table 4.1 below shows such statistical data for the years 2001, 2002 and
2003.

70
Table 4.1 : No. of Building Permits, Estimated Cost and Type of Building (Ministry of National Economy , Statistical Year Book, August 2002, August 2003 and
October 2004,)
Type of Buildings
Residential:
-Villas
-Houses
-Flats Buildings
Non- Residential:
-Commercial
-Industrial
-Educational
-Health
-Agricultural
-Govern. Offices
-Non- Gov. Offices
-Prayer Buildings
-Parking
-Warehouses
-Others
Dual-Purpose:
-Residen./Commercial
-Residen./Industrial
-Residen./Agricultural
-Others
Year 2001
No. of
Perm.
4,355
Cost in
(000)
USD
298,678
702
311
19,253
56,103
Year 2002 Year 2003
No. of
Perm.
5,329
Cost in
(000)
USD
385,125
No. of
Perm.
5,094
Cost in
(000)
USD
373,399
842
383
22,667
74,469
1065
370
36,452
74,755
115
48
60
12
-
18
2
194
-
7
70
168
10
16
2
13,580
14,282
58,698
10,512
-
16,653
3,978
14,771
-
4,066
23,767
51,558
1,352
1,037
120
128
50
84
9
8
31
2
205
1
7
109
210
10
16
3
30,722
6,692
38,620
6,547
333
8,156
107
12,493
432
996
16,663
80,613
5,223
1,248
39
15
4
19
3
169
112
34
81
-
6
89
208
-
25
5
15,272
12,475
40,147
7,602
9,519
10,020
1,079
11,749
-
1,747
16,910
79,737
-
2,093
562
Total 6,090 588,408 7,427 691,145 7,299 693,518

71
4.5
Consulting Engineering Services in Oman
The majority of the projects in the Sultanate of Oman are designed and supervised by a consulting firm. Therefore, the consultant is the main player on most construction projects built in Oman, especially if the client is far from the site and none of his technical staff are available for work supervision.
The Tender Board in the Sultanate of Oman registers consulting firms into three grades based on the technical requirements shown in Table 4.2. Based on these registration criteria, consulting firms registered with Tender Board in each category
(as on November 2005) are as follow:
1. Seventy-three consulting firms are registered in the first category;
2. Three consulting firm is registered in the second category; and
3. Seven consulting firms are registered in the third category
4.6
Typical Scope of Consultant Services in Omani Standards
The Standard Form of Agreement and Conditions of Engagement for
Consultancy Services for Building and Civil Engineering works, Sultanate of Oman
(1987) divided the consultant services into two phases: the design phase and the supervision phase. The scope of the design phase services includes the following stages:-
1.
Feasibility;
2.
Preliminary design;
3.
Detailed design;
4.
Production information;
5.
Bills of Quantities; and
6.
Tender action

72
Table 4.2 : Consulting Firms Grades (Tender Law, Royal Decree 86/1984)
The minimum requirements of the technical team
Grade
Senior Engineer Second Engineer Third Engineer
First University degree or its University degree University degree or its equivalent in the field is or its equivalent in equivalent in the field required with ten years experience, at least five of them in a position of required with seven years experience responsibility in the years experience specialisation required
Second University degree or its University degree equivalent in the field or its equivalent in required with seven specialisation is years experience, three required with five of them in the same years experience field
Third University degree or its equivalent in the field of specialisation is required with five years experience
The above services include some or all of the following activities but are not limited to:
1.
User requirements;
2.
Site conditions;
3.
Basic requirements of planning and design;
4.
Planning consents required from other Ministries;

73
5.
Site acquisition; and
6.
The preparation of all further drawings, architectural, engineering documents, calculations required for approval, and permission by the client and/or any relevant government department or public authority for construction of the work. In addition, their services also include the preparation of all drawings and other documentation to enable competitive tenders to be obtained for carrying out the work within the allocated budget sum.
The Standard Form of Agreement and Conditions of Engagement for
Consultancy Services for Building and Civil Engineering works, Sultanate of Oman
(1987) summarised the scope of the supervision phase into the following:
1.
Preparing contract sets of documents for signature by the contract and the client;
2.
Reviewing and approving as appropriate the detailed programme of the work as proposed by the contractor. In particular, the consulting engineer shall note the dates for any outstanding information, drawings or decisions required from the client or the consulting engineer and shall endeavour to ensure completion of the work;
3.
Preparing any further plans, drawings, designs and schedules necessary for carrying out the works;
4.
Examining and approving detailed drawings submitted by the contractor or sub-contractors;
5.
Arranging for inspection and testing during the manufacture and installation of such materials and plant as the consulting engineer deems should be inspected and tested;
6.
Issuing progress reports and other information as requested by the client;

74
7.
Examining tenders for the supply of goods and services where contained within provisional sums;
8.
Issuing requests for information to contractor(s);
9.
Supervising acceptance tests on site;
10.
Setting disputes or differences that may arise between the client and contractor(s);
11.
In the event of arbitration, the consulting engineer shall if requested by the client, makes available such existing information in his possession, which the client may require to present at an effective legal action;
12.
On completion of the works, provide the client with sets of "As Built" drawings (excluding shop drawings);
13.
Obtaining from the contractor and delivering to the client, prior to the completion of the works, such records and manufacturer's manuals as are reasonably necessary to enable the client to operate and maintain the work;
14.
Consultation with any other consultants appointed by the client regarding any matters related to the works; and
15.
Reproduction and dispatch of all documents, reports, drawings, maps, etc.

75
4.7 Fee Assessment of the Design Changes in Omani Standard
The Standard Form of Agreement and Conditions of Engagement for
Consultancy Services for Building and Civil Engineering works, Sultanate of Oman
(1987) provide two clauses for assessing the consultancy extra fee associated with the design changes. According to this standard, when the additional design services are necessary due to changes in the "user requirements" within the scope of the works requested by the client in writing after completion and approval in writing by the client, the consulting engineer shall be entitled to receive from the client as additional fee either:
(a) A percentage of the percentage fee of the budget sum or the percentage of the accepted tender sum whichever is the lesser and related to the value of the modifications, or
(b) A lump sum amount which shall be mutually agree in each design change based upon an estimate of the hours to be worked and the expenses to be incurred at the rates as stated in the contract documents
The following example illustrates the use of clause “a” above:
Assume the budget sum for a project is $600,000
Assume the accepted tender sum for the project is $500,000
Assume the original design fee for the project is $40,000
Thus:
40 , 000
The percentage of the design fee to the budget sum =
600 , 000
=
6 .
67 %
40 , 000
The percentage of the design fee to the accepted tender sum =
500 , 000
=
8 .
00 %
Assume the amount of the design changes is 2.5% of the original design
Then;
The additional design fee is the lesser of :
0.025 X 0.0667 X 600,000 = $1000
0.025 X 0.0800 X 500,000 = $1000
Hence, the additional design fee is $1000

76
For clause “b” above, the man-hours need to be estimated first then multiplied by the hourly rate that agreed in the design contract documents.
Referring to the above two clauses, it is clear that the problem still arise from estimating the amount of the design changes whether as a percentage of the original design fee as for clause “a” or estimating the man-hours as for clause “b”. These are the main causes of disputes on assessing the fees of the design changes as it will be seen, as example, in the result of the interviews with the professionals and in the questionnaire survey that are both part of this research. Hence, it is obvious that more rigid solution is needed to overcome such problems. This research is a step forward for such solution.
4.8
Chapter Summary
(1) This chapter presented general information about the Sultanate of Oman, in particular its location, the total area of the country and its total population.
(2) A brief on the basic Omani economy has been highlighted. It was pointed out that the crude oil and the natural gas are up to date the major sources of the Omani economy.
(3) The construction industry in the Sultanate of Oman is considered an important sector in the development of the country. Today there are 12,754 construction companies working in the industry. By the end of 2003, the share of the construction commerce in the Sultanate of Oman has reached USD 693,519 millions. This figure constituted about 3.0% of the Gross Domestic Product in Oman.
(4) The majority of the projects in the Sultanate of Oman are designed and supervised by private consultants engineering firms. As a result, today there are 83 consultant engineering companies in the business.

77
(5) It was found that in the Sultanate of Oman, the fee of modifying the original design for the majority of the government construction projects is being assessed on the basis of the percentage of the original design fees or the percentage of the budget sum whichever is the lesser. Alternatively, the fee of the design changes could be estimated on a lump-sum basis based upon the estimated man-hours per the hourly rate that quoted in the original contract documents. Both methods show difficulties in estimating the amount of the design changes or estimating the man-hours. This research focuses on finding more rigid solution to overcome such difficulties.

CHAPTER 5
RESEARCH METHODOLOGY
5.1 Introduction
This chapter discusses the procedural plan and the methods that have been considered for this research work. It starts discussing the initial investigations that were necessary to build up the knowledge on the issues related to design changes and to justify the need for this research. Then the chapter presents the methods of data collection which includes interviews with professionals in the construction industry, case studies and questionnaire survey. Finally, it discusses the methodology that has been considered for developing the proposed method to assess the consultancy fee of the structural design changes as well as the tool to validate the developed method. An explanation was given to each method in term of their relation to the study, selection criteria and the anticipated result from each one. The order of the methods has been chosen in such away that it explores the subject, identify the shortfall of appropriate procedures to assess the fees of design changes, builds-up the knowledge and, in the end, provides answers to the points under the investigation. The adopted order is expected to provide easy understanding and fair transmission between the topics.

79
5.2 Literature Review
Fundamentally, no research work stands on its own. Each study relates in some way or other to previous ones within the research area. Therefore, it was necessary to search for and examine at early stage all relevant theories and literature in order to build up the boundary of knowledge, explore the issues along with the areas of concern and look for solutions that may never been realized before or not sufficiently addressed and to prevent repeating the already investigated topics.
To achieve the above objectives, related previous studies were collected from books through the university main library, journals articles using the university data base, thesis, internet, seminar notes and conference papers. As a result of this literature search, it was essential to provide a comprehensive background on the principle of the design changes on reinforced concrete buildings, their sources, causes and impacts on the life cycle of the projects as well as the previous attempt to manage them. The principle of the consulting engineering practice has been also highlighted with emphasis on the existing methods of charging for engineering services. The literature review did not only provide a view on what has been accomplished so far on the subject but also addressed the related issues that are necessary to gain familiarity on the topics under this investigation.
The importance of this stage is to draw a boundary of knowledge from the previous studies that in relation with the investigated topic, to provide up to date background of the research area under discussion and to come up with something different that have not been investigated and/or adopted before by others so that the existing knowledge of the subject is expanded. It is an effective tool to identify and formulate the problem of the study and to justify the need for the research.

80
5.3 Interviews with Professionals
Interviews are one of the most commonly recognised forms of qualitative research method that have been used to solicit opinions based on different backgrounds (Mason, 1996). The interview is a technique in which a set of questions are addressed verbally to the respondent, who in turn gives replies verbally. Thus an interview involves personal interaction between the interviewer and the respondent. The interview technique permits the interviewer to elaborate questions and to probe the respondent for further information (Mayer, 1980). They provide in depth understanding of the interviewee’s point of view and furnish the requested details within short time. Burgess (1984) calls them “conversations with a purpose”.
The intention of the interviews with the professionals for this research was to obtain preliminary opinions on the extent of the research problem within the content of the construction industry in the Sultanate of Oman and hence to justify the need for this research. Emphasis was given to identify the sources, causes and impacts of the design changes as exist in the construction industry. It is also aimed to identify the existing methods for assessing the engineering consultancy fee for modifying the original design and their limitations as seen by the professionals.
A format for the interview scope was prepared to consist of eleven semiclosed questions to cover the main points under discussion. The questions have been sent to the selected professionals in the Sultanate of Oman prior to the discussions with a view to optimise the interview time. In spite of advance notice, each interview took 40 to 60 minutes. Twelve industry experts were interviewed during December 2003. The professionals were selected to represent the opinion of consultants, contractors and clients who are continuously involved in the construction industry. Four interviewees from each group were selected in the following manner:
• The selected consultants were well known international offices holding excellent grade (top grade in the country for consulting engineering firms)

81 working on large scale multi disciplines projects with majority of their work being in structural design and supervision
• The selected clients were from governmental organizations that have their own large scale multi-professionals engineering offices dealing with both contractors and consultants to design, supervise and construct their projects. They are heavily involve in the construction industry and are usually responsible for finalising the designs, contract documents, financial matters and for the settlements of final accounts.
• The selected contractors were well established and well known in the country holding excellent grade (top grade in the country for construction companies working on large scale projects with majority of their work on buildings construction.
The interviewees from each group were selected to be either general managers, head of engineering sections or chief quantity surveyors that have extensive experience not only in engineering oriented works but also on contractual matters and solving disputes. The responses have been recorded in a tabulated form to highlight the opinions of each respondent and to give clear comparisons between them.
5.4 Case Studies
Case studies are useful for tracing the history of particular issues so that actual facts can be obtained. They are useful when investigating human inputs in complicated process (Blockley 1986). Case studies become particularly useful where one needs to understand some particular problem or situation in great depth, and where one can identify cases rich in information (Patton, 1987). Qualitative analysis through case studies is particularly useful for investigating why a relationship exists (Eisenhardt 1989).

82
Three case studies have been investigated for this research. They are all reinforced concrete buildings from the Sultanate of Oman. It is aimed that the selected cases would provide in-depth knowledge and better understanding on the size of the research problem; give actual examples of the issues under discussion and demonstrate the limitation of the current methods that have been used by the consultants to assess the fee of the structural design changes. These case studies were also aimed to identify the engineering time required to carry out the changes to its counterpart drafting time in order to make comparison between the estimated engineering/drafting times from the case studies and the estimated engineering/ drafting time that has to be assessed in the later parts of this research work.
The case studies were limited to medium size concrete building design within the government projects executed during the last 8 years (due to good documentation records, good filing system and comparatively easy access).
Clients’ instruction for issuing variation orders and the consultants’ claims for design changes were used as a tool to determine the nature and the fee of the design changes for each case.
Case studies may reveal some facts about the projects which the owners are possibly consider them confidential for publication. They have in many cases commercially sensitive issues. Therefore, extra care was deemed necessary to ensure reasonable level of confidentiality. To this end and as requested by the owners, their names, names of the projects and the total construction cost have been excluded in the study. However, their description, fee of structural design and fee of design changes are all included. The above restrictions are acceptable since the study is mainly related to the fee of structural design changes and it is not necessary to include the total construction cost of the projects.
5.5 Questionnaire Survey
Questionnaire survey is an effective, convenient, and economical investigative tool for obtaining data and sampling the opinions of individuals in

83 spatially diverse locations (Zhang. 2004). Questionnaires usually provide large amount of data in a short time with relatively ease of preparation, distribution and tabulation of answers and responses can be given easily and quickly. Therefore, a closed end questionnaire was designed for this research work taken into consideration the aim and objectives of the study. The questionnaire survey is aiming to collect representative data from the industry to verify the findings of the previous work on the subject, to update the existing knowledge and to re-evaluate the extent of the problem as it stands to date. Hence, the questionnaire was set up to obtain professional opinions on the following aspects:
• Causes, sources and impacts of the structural design changes on reinforced concrete buildings;
• The possible corrective actions and preventive measures to minimise the avoidable design changes; and
• Level of satisfaction on the existing methods for assessing the design changes
5.5.1 Design of the Questionnaire
The questionnaire survey was designed to verify the significant level of the potential factors that are associated with design changes. While designing the questionnaire, considerations have been taken for the aim and the objectives of the study with an intention to provide sufficient background and to obtain professional opinions from the industry to cover the issues that are within the limitation of this research work. The findings of the literature review and the result of the structured interviews with professionals in building industry that discussed in the previous parts of this research work were used as a basis for the questionnaire’s content and its format. The aim of the investigation was to establish the following aspects:
ƒ Estimating the significant level for each factor of causes, sources and impacts of design changes ;

84
ƒ Establishing the significant level for each factor of the possible corrective actions and preventive measures to minimise the avoidable design changes; and
ƒ Establishing the significant level for each possible limitation of the existing methods that are widely used by the professionals to assess the fee of design changes.
The questionnaire survey contains an introductory section for general information in addition to eight sections to cover the main issues under investigation. The introductory section begins with general information which provided a useful contact point for clarifying queries about any answers given.
This section also includes the identification of types of organizations and number of years that the respondents have been in the industry. The first three sections of the questionnaire focused on the causes due to clients’, consultants’, and contractors’ design changes. Section four covers the sources of design change while section five deals with their impacts. Possible corrective actions and preventive measures to minimise the avoidable design changes are presented in section six of the questionnaire and section seven aimed to identify the preference order of using the existing methods for assessing the fee of design changes. The last section highlights the possible limitations of the existing methods that are in use for fee variation assessment associated with design changes. At the end of each section, the respondents were requested to add any other factors that in their opinions are appropriate to the study and this resulted in identifying more factors which have been included in the investigation.
The questionnaire was distributed in the Sultanate of Oman, in the capital area, Muscat, and conducted in two stages. The first stage was used as a pilot study test and the second stage was used for the main survey. An explanation to each stage is given on the following sections.

85
5.5.2 Pilot Survey
A pilot survey questionnaire was performed to identify the right questions and to present them in a clear format and high-quality presentation. Special care went into phrasing the questions in a language that is easily understood by respondents. The pilot survey was also used as an opportunity to identify any other information, suggestions, comments or factors appropriate to the study that could be included in the second stage main survey. The responses of the pilot study were used to test the adequacy of the proposed statistical analysis and to determine the sufficiency of the expected results. The pilot study was performed with six selected professionals who are closely involved in the building industry and have extensive experience dealing with the issues of design changes. The professionals for the pilot study have been chosen as follow:
ƒ Two Clients government organizations;
ƒ Two Consultants Engineers; and
ƒ Two building Contractors
Five responses out of the six have returned in the pilot survey stage. Most of the comments were received from the clients pertaining additional factors to minimise the design changes as stated in the last part of this section.
5.5.3 Main Survey Questionnaire
The responses in the first stage pilot study illustrated the lack of clarity on some of the questions that have been either left un-answered or provided with unexpected replies. As a result, many amendments have been made to the questions for the main survey questionnaire that have unsatisfactory responses. It was also deemed more appropriate for the main survey to break down some of the questions which contain many variables for better ranking assessment. Many respondents have added more factors to the ones that have been identified for the pilot study which in turn have been incorporated into the main survey. The questionnaire’s

86 format has been also improved from that of the pilot study. A copy of the main survey questionnaire is presented in Appendix B
5.5.4 The Population and the Distribution of the Questionnaire Survey
The main population of the questionnaire survey was limited to the following:
• Consulting engineering firms holding an excellent grade;
• Clients representing government agencies; and
• Contractors holding an excellent grade
The rationale behind limiting the population of the questionnaire survey to the above is that they usually take on large scale projects in the country in which design changes are normally encountered in such projects and hence they are more familiar with the issues of the design changes. Smaller consultants and smaller contractors deal with smaller projects and hence not much design changes takes place. In turn, their familiarity of the issues related to design changes is very limited, if there is.
The main survey questionnaire was personally handed over to the respondents and an interview was available to answer any questions relating to the questionnaire. It was distributed to 42 carefully selected construction industry professionals representing Clients, Consulting Engineers and Contractors who particularly deal with design changes issues. Completed forms were requested to be collected later or faxed back. Follow-up telephone calls and subsequent visits have been made. Over a period of two months after distributing the questionnaire,
27 responses were received and the composition of the respondents is given in
Figure 5.1.

87
Consultants
33%
Contractors
26%
Clients
41%
Figure 5.1 :
Type of Organization Represented
The above figure represents 11 responses from clients, 9 from consultants and 7 from contractors. The rational to include the three groups is to obtain opinions from all concerned professionals’ representative working in building industry and to confirm the assessment of the questions to each other for better evaluation. The respondents who participated in this questionnaire survey have been engaged in the construction industry for many years, ranging from a minimum of 12 years to a maximum of 40 years with a mean period of
22 years. Therefore, the information provided is considered reasonably reliable and realistic. Figure 5.2 shows the distribution profiles of their experience in the construction industry.

88
40
35
30
25
20
15
10
5
0
Clients Consultants Contractors
Figure 5.2 : Distribution Profiles of Work Experiences of the Three Groups of
Survey Respondents
5.5.5 Methods of Analysing the Questionnaire Survey
It is important to consider at early stage the method of analysis before developing any system of data collection. The reason for this being that the method of analysis determines the type of data to be collected and structure of questions.
One of the scientific methods that have been widely used to test hypothesis and has been considered for this study is a statistical analysis. Firstly, the significant levels of importance for factors related to design change that are under the investigation have been ranked using Likert Scale (also called Ordinal Scale). Secondly, appropriate statistical methods, as discussed in the forthcoming paragraphs were used. Lastly, the responses have been tested for agreement by using t-statistic test.
This procedure was found as a suitable technique to be employed for this study. To rate the factors Table 5.1 outlines the assigned values of Likert Scale with its appropriate designation.

89
Table 5.1 : Ranking System for the Questionnaire of this Study using Likert (Ordinal) Scale
Section(s)
1 to 6 and 8 7
Rate 1
Rate 2
Rate 3
Rate 4
Disagree
Slightly Agree
Agree in Average
Mostly Agree
First choice
Second choice
Third choice
Forth choice
Rate 5 Strongly Agree Fifth choice
The data collected for this questionnaire survey were analyzed using the
“Mean Score” terminology. This technique was used by Assaf et al.
, (1995) to establish the significant level of the causes of delay in large building projects in
Saudi Arabia, as suggested by the owners, the architects/engineers and the contractors. The method was also used by Chan and Kumaraswamy (1996) to establish the “Mean Scores” for the construction time performance in building industry in Hong Kong, as acknowledged by clients, consultants and contractors and used by Abd. Majid (1997) in his research work to establish the “Average
Index” for non-excusable delays in construction as declared by contractors and clients. The five point Likert Scale described previously was used to determine the relative ranking of different factors by assigning ranks to the mean score, with low mean score assigned low ranks and high mean score allocated high ranks. These rankings made it possible to have cross-reference to the relative level of importance to compare the responses of each participated group. The Mean Score ( MS ) for each factor was computed by the following formula, Chan and Kumaraswamy
(1996):
MS =
∑
( fxs )
N f
(1 ≤
MS
≤ 5), (1)
Where:
f : frequency of responses to each score for each factor

90
s : score given to each factor as ranked by the respondents
N f
: total number of responses concerning that factor
In order to combine the opinion of the three participated groups to determine the level of significant to each factor, a “Weighted Average” ( WA ) for each of the factors was obtained from the following expression; (Chan and
Kumaraswamy, 1996):
WA
=
∑
Where:
⎜
⎜
⎝
⎛
⎢
⎢ ⎣
⎡ n
N g
⎟
⎟
⎠
⎞ xMS
⎥
⎥ ⎦
⎤
(1 ≤
WA
≤ 5), (2)
n : number of responses for each group, for this study n = 11 for
clients group; 9 for consultants group; and 7 for contractors.
N g
: total number of responses for the three participated groups;
N g
= 27
MS : corresponding Mean Score for that group in respect of each
factor
Mean Scores,
MS
, and Weighted Average,
WA
, could be further interpreted back to reflect the respondents rating. To achieve this,
MS
and
WA
can be split into discrete categories (Abd. Majid and McCafer 1997) as follow:
(1) Disagree 1.0 ≤
MS or WA < 1.5
(2) Slightly Agree 1.5 ≤
MS or WA < 2.5
(3) Agree in Average 2.5 ≤ MS or WA < 3.5
(4) Mostly Agree 3.5 ≤ MS or WA < 4.5
(5) Strongly Agree 4.5 ≤ MS or WA ≤ 5.0
Similar categories can be established for other ranking classifications and the computed MS and WA from the analysis can then be converted to the above categories.

91
The agreement between rankings of any two groups for any given number of factors need to be tested. Kometa et al (1995), Assaf et al (1995) and Abd Majid
(1997) have used a Spearman correlation analysis to test such agreements. This method is a commonly used tool as a measure of association, in this case between clients and consultants, consultants and contractors, clients and contractors. The expression for calculating the Spearman’s correlation coefficient is as follow,
Mendenhall et al.
, (1993): r s
= 1 - f n
6
(
∑
2 f d n
− i
2
1 )
(-1 ≤ r s
≤ +1), (3)
Where : d i
: the different between the rank given by one group and the rank
given by another group f n
: total number of factors ranked by any two groups for any
given category
In the above expression, a maximum rank correlation coefficient of +1 indicates perfect linear correlation while a minimum value of -1 indicates negative correlation. In case of zero value, no correlation exists.
To test the rank correlation coefficient (the null hypotheses, H
0
), a twotailed t-statistic test was used for this study at a level of significance of 5%. H
0
: two groups of participants in the building industry, clients Vs consultants, clients
Vs contractors and consultants Vs contractors, do not agree in the ranking of important factors; H
1
: otherwise.
Hence; reject H
0 if -t st
> t cal
> + t st
Where:
t st
: t-statistic and obtained from standard t-statistic tables
t cal
: t-calculated from the following formula: t cal
= r s
1 n
−
− 2 r s
2
(4)
r s and n as defined above

92
5.6
Methodology for Development of an Alternative Method to Assess the Fee of Structural Design Changes
Twelve different types of low rise reinforced concrete buildings ranging from one floor to four floors have been designed both manually and by STAAD Pro software and drafted by AutoCAD. The selected buildings are all from the
Sultanate of Oman and have been already constructed in the country. Man-minute times (times in minutes for one structural engineer) have been recorded for designing and drafting each structural activity. As an example, the time required for one structural engineer to design footings, columns, beams, roofs, etc, have been established for each building. The rationale behind using the minutes rather than the hours as used in the practice (refer to the result of the interviews and the case studies) is to avoid using fraction of the hour since most of the recorded timing for designing the structural elements as defined in this study are less than an hour.
In turn, using the minutes have resulted in better representative of the timing in the production of the graphs as it will be seen in the forthcoming chapter. With the time records for designing various structural members and elements, the percentage of time for each structural group has been established. In turn, this method has led to a form of quantifying the amount of the structural design for each element percentage wise which then correlated to the amount of the design changes proportionally and hence to the original design fee.
The above methodology has been extracted from the result of the case studies, the interviews with the professionals working in the construction industry in the Sultanate of Oman as well as from the result of the questionnaire survey that all have been carried out at the earlier stage of this research work. The result of these initial investigations revealed that the most common method that is in use by the consultants to claim extra fee due to design changes in the Sultanate of Oman is the man-hours method. There are many examples that can be seen in the case studies where the consultants have submitted the man-hours to their clients that have been claimed to be the actual man-hours spent to execute the changes.
However, if the man-hours are not totally accepted by the clients, they can not be assessed and hence the disputes normally arise due to the lack of a method to assess the claimed man-hours.

93
The man-hour rate for services charges has been used not only in the consultancy industry but also in other disciplines. As an example, in the United
Kingdom, Bournemouth International Airport Ltd Company has been using the man-hour rates for labour charges associated with the airport fire & rescue fire appliance and crew services. The Office of Administration in State of Missouri,
United States, have also been using the man-hours rates for charging customers require professional services for special applications in connection with their developed commercial software. Other example is Dubai Central Laboratory
Department where the fee for issuance of Certificate for Good Jewellery Trading
Practice (GJTP) is calculated based on the man-hours spent to carry out the required tasks in the certification process.
Similar approach have been adopted for this research work accept that more detailed break down of the timing is maintained in an intention to approximate the time that most likely be required to design each structural members in any given building so that an assessment to the claimed design changes can be carried out.
The result of this stage has led to development of a mathematical expression to assess the fee for design changes. The followings are the more detailed steps that have been adopted:
Step 1. Twelve reinforced concrete buildings have been selected for structural
designing and drafting in the following manner
• One floor : Three buildings
• Two floors : Three buildings
• Three floors : Three buildings
• Four floors : Three buildings
Step 2. The buildings have been designed manually and drafted by AutoCAD
Software
Step 3. One floor and two floors buildings have been designed both manually and
by STAAD Pro software to compare the results of the two methods.
Step 4
. The following categorization for the structural group members have been
used:

94
• Structural group members 1 : Columns
• Structural group members 2 : Plinth beams
• Structural group members 3 : Floor beams
• Structural group members 4 : Slabs
• Structural group members 5 : Footings
• Structural group members 6 : Stairs
• Structural group members 7 : Arches
• Structural group members 8 : Sections
Step 5
. Time, in minutes, has been recorded for designing each structural group
members
Step 6.
Time, in minutes, has been recorded for drafting each structural group
members
Step 7
. The percentages of time requires for designing and drafting each structural
group members have been calculated. Hence;
Total Time of that Group
% of time for each group members = ────────────── X 100
Total Time of All Groups
Step 8 . It has been assumed that the percentage of time for designing and drafting
each structural group member is the percentage of total contract fee to
that group.
Step 9 . It has been assumed that the amount of design changes to any number of
group members is proportional to its total percentage time and hence to its
fee.
Step 10.
The above data has been used to propose a method for assessing the
consultancy fee associated with design changes
Step 11.
The developed method has been sent to experience professionals for
assessment and validation
Step 12.
Examples have been provided to demonstrate the practical use of the
proposed method

95
5.6.1 Design Parameters and Assumption for the Building Design
The followings have been considered in generating the data for the development of the method. The design parameters and the assumption that have been made are the most common criteria for the buildings design in the Sultanate of
Oman.
• The buildings have been designed for local Omani conditions ;
• British codes of practice and British standards have been used;
• The buildings have been designed for dead loads and live loads only;
• No earthquake or wind loadings have been considered, no shear walls (not common for designing buildings in Oman);
• Soil bearing capacities assumed to be between 100 to 200 KN/m 2 ;
• Foundations have been selected to suit the most appropriate loading conditions;
• Pile foundations have not been considered, not common in Oman; and
• Construction drawings have been produced with basic structural details only
5.6.2 Details and Classifications of the Selected Buildings
Each building under this research has been given a reference number to represent the number of floors and an identification letter. For instance, one floor buildings have been assigned reference numbers 1A, 1B and 1C while for the two floors buildings the references are being 2A, 2B and 2C with similar designation for the three and four floors buildings. Architectural ground floor plans for each of the building in this research work is attached in Appendix C and their basic details are shown in Table 5.2 below. The type and the nature of these buildings are the most common ones for the low rise concrete buildings in the Sultanate of Oman.

96
5.6.3 Source of the Structural Design of the Buildings
For the purpose of this research work, the structural design and drafting of the buildings have been carried out by two senior structural engineers working in two different international consulting engineering firms along with the Researcher.
The distribution of the buildings’ design was as follow:
• One Senior Engineer : Three buildings. (Buildings Ref. 2A, 3A and 4A)
• Other Senior Engineer : Three buildings. (Building Ref. 2C, 3C and 4C)
• The Researcher : Six Buildings. (Buildings Ref. 1A, 1B, 1C, 2B,
3B and 4B)
Table 5.2 :
Basic Buildings Details
Building
Reference
No. of Floors Building Type Ground Floor Area
The rationale behind involving independent senior structural engineers from international consultants firms in the structural design of the buildings are to obtain the data from more than one source and hence better data representative, to get continue technical supports and discussions in the existing structural design practice

97 and to develop the anticipated method of fee variation along with the professionals that are in the industry.
The required level of design and drafting information were formulated in writing and discussed in detail with each of the above engineers along with the methods of designing and detailing so that all designers follow similar design and drafting approaches. Architectural drawings and details were given. The consultants were asked to fill up the times required to carry out each activity in the provided time table sheet.
5.6.4 General Structural System for the Buildings of this Study
All buildings on this research work have been designed using the British
Standard BS8110 (1997). This code of practice is adopted in the Sultanate of
Oman. The general structural arrangement of the buildings was frame structures.
Thus, loads from roof slabs get transmitted to roof beams which in turn get transmitted to the columns then to the footing and finally to the soil. Plinth beams, the beams that are located at the ground floor level and usually provided for restraining the buildings and to support the walls of ground floors, have been provided. Top level roofs are flats concrete roof. This type of structural arrangements is the one that have been adopted and approved in the Sultanate of
Oman.
5.6.5 The Principle of the Adopted Structural Design
An intensive discussion with the professionals along with various references of the commonly used contract documents in the Sultanate of Omen have been taken place at the early stage of this part of the research to identify the mostly used methods of the structural design, the level of detailing and the common contracts’ design clauses. Similar approach to the finding of what is in the practice in Oman

98 has been followed so that the adopted method of the design matches with the existing practice in the construction industry. It has been revealed from this exploration phase that the majority of the consultants have been designing the reinforced concrete buildings either manually or by a combination of manual design along with computer design software. Most of the consultants have developed their calculations in which Microsoft Excel is the dominated one. Nevertheless, only certain structural elements such as columns, beams and/or, in some instances, footings are carried out by computer Software. Due to this, and to get more consistent data, the structural design of the buildings for this study was carried out manually.
In addition, the one floor and two floors buildings have been designed both manually and by STAAD Pro software. The reason behind this is to give comparison between the results of the manual design and STAAD Pro software design. Due to the nature of the designing process by the commercial structural design software such as STAAD Pro, it is not possible to allocate exact timing for designing each structural group members. Hence, the time required for modelling the structure is a common time for all structural members. An assumption might be made to this extent but, nevertheless, it was found more practical to build up the proposed method with the manual design to avoid the uncertainties of the structural analysis and design software such as STAAD Pro software.
Furthermore, it has been noticed from many contract documents in the
Sultanate of Oman to break down the fee of the structural design into two main items namely preliminary design fee and detailed design fee. Each stage has its own fee item which might be used as a reference for releasing the payment certificates to the consultants on the completion of each part of the work. Similarly, the structural design for the purpose of this study has been divided into preliminary design phase and detailed design phase to match with the existing practice.
Preliminary design has been assumed to consist of the general arrangement of all structural members with approximate sizes including the foundation. This

99 stage does not need detailed calculations and reinforcement details. On the other hand, detailed stage requires exact sizing and all relevant construction details.
5.7 Questionnaire for Validating the Developed Method
5.7.1 Design of the questionnaire
The questionnaire was designed to obtain professional opinions from consultant engineers who are in the construction industry and being encountering design changes in their major previous projects especially in RC buildings. The aim of the questionnaire is to validate the developed method in term of its suitability, effectiveness and its practicality. It has been structured in a good quality format, short phrases and in a simple language for easy understanding. The respondents have been asked to rate their opinions to each pre-determined observation using a rating scale from 1 to 5 in which rate 1 was allocated for no agreement in the observation, rate 2 for slight agreement, rate 3 for agreement in average, rate 4 for most agreement and rate 5 for strong agreement.
A brief background of the subject under investigation was attached to the questionnaire and included a definition of the design changes, the justification of the research in this subject and the necessitation for better method to assess the fee of the structural design changes. Brief was also provided for the adopted methodology in which the proposed method was based on with highlight on the principle of the adopted structural design. The proposed method in term of tables for the estimated coefficients, mathematical expression and definitions of the terms to be used in the mathematical expression were all affixed to the questionnaire. A practical example was appended as well to illustrate the use of the proposed method. The rationale for attaching the above sections is to give the respondents a reasonable background to the main parts of the questionnaire since many observations that need to be viewed by the respondents were related to these sections. The distributed questionnaire is attached in Appendix E.

100
The distributed questionnaire started with an introductory section for general information in addition to eleven pre-determined observations carefully formulated and considered necessary for the validation of the proposed method.
The introductory section begins with general information which provided a useful contact point for clarifying queries about any answers and/or given information.
This section also includes the identification of types of organizations and number of years that the respondents have been in the industry. In the next section of the questionnaire, the respondents have been asked to state their opinions on the principle of the proposed method, their level of acceptance of the adopted methodology, their view on the proposed coefficients and their view on the definitions of the parameters used in the mathematical expression as well as to get their opinions on the practicality and the suitability of the method. Opinions have also been looked for the level of confidence in the proposed method and the appropriateness of the method to be in the contract documents for assessing the consultancy fee of the structural design change. At the end of each section, the respondents have requested to comment on each raised observation that feel in their opinions are appropriate to the study and this have been taken into consideration.
The questionnaire for validating the proposed method was distributed in the
Sultanate of Oman, in the capital area, Muscat. It was distributed to seven, top grade, leading international consultant engineers who have wide experience dealing with design changes and were expected to contribute their knowledge to the subject in general and to the proposed method in specific. All consultants have responded and returned the questionnaire with many comments in which some of their comments are useful to the study. The method of data analysis that has been described in Chapter 5 has been adopted for this questionnaire wherever applicable.
5.8 Development of the Guidelines
Consideration has been given in this research to develop practical guidelines for improving the consultancy design documents with respect to managing design changes in reinforced concrete buildings. In constructing the guidelines, reference

101 has been made to the manual published by the American College of Cardiology
(ACC), Section II: Tools and Methods for Creating Guidelines (2004). The extracted steps from this manual are as follow:
•
Step One: Determine the Guideline Scope and Objectives
The scope of the developed guidelines is within the area of the engineering consultancy industry in the Sultanate of Oman. The main objective of the developed guidelines was to establish the necessary steps for improving the existing engineering consultancy contract documents with respect of managing design changes.
•
Step Two: Define and Conduct Appropriate and Comprehensive
Literature Searches
Once the scope and the objective of the guidelines have been determined, comprehensive searching of the published works and the result of the investigations for this research (Interviews, case studies and questionnaire survey) were examined.
There were no published practical guidelines found in previous works for managing design changes.
•
Step Three: Sort and Evaluate the Evidence
After the literature search results have been established, a list of initial guidelines for managing the design changes was constructed from the result of the literature searching, the result of the interviews, case studies and the questionnaire survey.
•
Step Four: Synthesise and Interpret the Evidence
To improve the consistency of the guideline content, both within and between the guidelines, a cross check in the terminologies was conducted so

102 that there is a consistency in the terminologies within the guidelines and unambiguous language has been used.
•
Step Five: Write Recommendations (Guidelines) Based on Expert
Interpretation of the Evidence
The guidelines have been condensed in complete sentences. Separate guidelines have been written to each specific objective. The guidelines were constructed in a simple format, easy interpretation and intended for practical implementations.
5.9 The Method of Validating the Developed Guidelines
The guidelines that have been developed for managing the design changes were validated by the professionals working in the consultant engineering firms.
Delphi Method has been used as a tool for validating the developed guidelines. The guidelines and the result of the validation process are presented in Chapter 8 of this research. The forthcoming sections highlight the principle of the Delphi Method.
5.9.1 Background of the Delphi Method
The Delphi concept was developed from the American defence industry.
Project Delphi was the name of the study undertaken by the Rand Corporation for the US Air Force in the early 1950s concerning the use of expert opinion
(Robinson, 1991). The objective of the study was to “obtain the most reliable agreement of opinions among a group of experts by series of questionnaires combined with controlled feedback” (Linstone and Turoff, 1975). It was originally developed for market research and sale forecasting purposes (Goldfisher, 1992).

103
According to Hartman and Baldwin (1995), the Delphi Method typically consists of three or more iterations of questions. A panel of experts is first assembled. This panel is frequently limited in size for practical reasons. The panel is then asked for general input and commentary on the issues that are under study.
On the basis of the comments of the panel, a second round of more focused questions is developed. The panel is then approached again with these new questions and with feedback of the previous responses. The successive rounds are typically allocated for the panel to re-consider their previous responses if deemed necessary in light of overall result from earlier rounds (Hess and King, 2002). The process stops when consensus has been approached among participants or when sufficient information exchange has been obtained (Delbeeq and Gustafson, 1975).
The Delphi method is an iterative forecasting procedure characterised by three features (Dickey and Watts, 1978): anonymity; iteration with controlled feedback; and statistical response. Anonymity (confidentiality) is often adopted to promote frank discussion, improve group response, and reduce the sensitivity among the panellists. Panel members remain unknown to one another during the process.
Alder and Ziglio (1996) noted a number of benefits to the Delphi approach.
These include providing a framework that allows individuals with different backgrounds and in different locations to work together on a problem; providing an equal opportunity for all involved; and producing documentation of the decision making process. Alder and Ziglio (1996) added that the Delphi approach offers an additional advantage in situations where it is important to define areas of uncertainty or disagreement among experts. In these instances, the Delphi method can highlight topics of concern and evaluate uncertainty to a quantitative manner.
Group evaluation of belief statements made by panel members is an explicit part of the Delphi method (Robinson, 1991). It can represent the best forecast available from a consensus of experts (Corotis et al.
, 1981). Goldstein (1975) pointed out that, although the group view has a higher probability of being correct than an individual, its success depends principally on the careful selection of the panel and the formulation of questions. The most difficulties of the Delphi method however

104 lie in maintaining the high level of response and in reaching and implementing a consensus (Robinson, 1991).
5.9.2 Selection of the Professionals for the Delphi Questionnaires
The success of the Delphi method depends principally on the careful selection of the professionals. For this study, the participating professionals have been selected to provide opinions on the suitability, practicality and effectiveness of the proposed method as a means of validation. Since the information solicited for the Delphi technique requires in depth knowledge and sound experience, appropriate selection criteria of the participants for each investigation shall be formulated carefully (Bryman, 1996; Morgan, 1998). The following criteria were devised to correctly identify eligible participants for the Delphi questionnaires associated with this study.
• Participants to have extensive knowledge and sound experience of the issues related to design changes in reinforced concrete buildings;
• Participants to have working experience in large scale reinforced concrete projects in which substantial design changes are normally encountered;
• Participants to be available, accessible and show interest to participate in the study; and
• Participants to be currently working in leading consulting engineering firms or clients directly encounter in their main projects substantial design changes
In order to obtain the most valuable opinions, only practitioners who met all the above criteria were selected.

105
5.9.3 Identifying the Number of Professionals for the Delphi Method
There is substantial debate regarding the optimal size of the Delphi panel within the literature (Williams and Webb, 1994). Adler and Ziglio (1996) believe that the size of the expert panel is dependent on the number of issues covered. The aim is not to accumulate the opinions of the experts to represent any population.
Rather, the goal of the Delphi study is that all relevant issues are identified and explored. They suggest 20-30 participants for each issue. By contrast, Linstone and Turoff (1975) argue that there is no optimum figure of respondents for the
Delphi study, but suggest a minimum requirement of 4-7 respondents.
For this study seven senior professionals working in well established engineering consultancy firms in the Sultanate of Oman were selected to provide the required information and hence to validate the proposed guidelines. The expertise of the selected professionals was sufficiently broad in the design changes so that a confidence has been built in this group to provide the meaningful results needed to assess the practicality of the proposed guidelines.
5.9.4 Identifying the Number of Rounds for the Delphi Method
Several studies have examined how many rounds are required for responses to stabilise. Brockhaus and Mickelsen (1977) reported that most studies contain three or fewer iterations. Dietz (1987) reported that most changes in the Delphi response occur in the first two rounds. Other researchers too have reported that not much is gained in the conventional Delphi method by iterating more than twice
(Gunhan and Arditi, 2005). In fact, a highly suggestive outcome of Dalkey et al.
,
(1972) experiment was that answers were most accurate on round two and actually became less accurate on subsequent rounds. There is, then a move away from multiple-round Delphi toward a view that two rounds are sufficient. Indeed, according to Mitchell (1991), the number of rounds needs to be as few as possible; otherwise exhaustion and time pressure will result in unsuccessful rounds. It was

106 also reported that maintaining participant interest in the questionnaire study would become progressively more difficult after each additional round (Beech, 1999).
5.9.5 Format of the Delphi Rounds for this Research
The Delphi method adopted in this research consisted of three rounds. In the first round of the Delphi approach, it was intended to construct a practical set of guidelines that in the opinion of the participated professionals are important for improving the existing consultancy contract documents with respect of the design changes along with guidelines to manage them when they occur. In the second round of the Delphi questionnaire, the set of the guidelines resulted from round one was provided and the participants were asked to rate the significant level of each guideline. In the third round of the Delphi method, the respondents were provided with the results from round two. They were asked to reconsider their round two scores and decide whether they would like to adjust them. The consistency of the results over the last two rounds were analysed and compared. The details of the adopted Delphi rounds are presented in the next sections.
5.10 Chapter Summary
(1) This chapter presented the procedural plan and the methods that have been considered for this research work.
(2) The chapter highlighted the detailed methodology for the interviews, case studies and the questionnaires’ survey that all were part of this study.
(3) Detailed procedure for developing an alternative method to assess the fee of structural design changes has been presented.

107
(4) The chapter also furnished brief discussion on the principle of the adopted structural design for this research work.
(5) For the validation of the developed guidelines, the Delphi Method has been proposed and its background has been provided at the end of the chapter.

At the initial stage of this research work, it was necessary to investigate the issues that are related to the design changes through more than one source in order to build up a solid level of confidence in the research problems and hence to come up with better methods of assessing them. Such issues have been discussed firstly with the professionals working in the construction industry in the Sultanate of Oman by mean of interviews so that independent initial opinions could be obtained from the concerned professionals. Secondly, it was also deemed necessary to provide case studies so that actual examples on the extent of the problems associated with design changes can be observed. This stage of the investigation ended up with a questionnaire survey to identify the significant level of each factor under investigation as perceived by the professionals. This chapter discusses in details the findings of the interviews with the professionals, the outcome of the case studies and the result of the questionnaire survey.
A detailed methodology for each of these methods has been presented in chapter 5 of this research.

109
The semi-structured questions for the interviews have focussed on the sources, the causes and the impacts of the design changes. The interviews also aimed to identify the problems associated with them due to the lack of the guidelines in the existing design contract documents to assess their fee and to identify the existing methods for their assessment. The targeted respondents for the interviews were the consultants, the clients and the contractors. These respondents represent the engineering professionals working in the Sultanate of Oman. The result of the interviews in term of is shown in
Table 6.1, Table 6.2 and Table 6.3. A comparison between the respondents of the consultants, the contractors and the clients are presented in Table 6.4.
The following sub-sections highlight the main findings of the interviews results
The data obtained from the interviews shows clearly that projects are most unlikely to be completed without design changes. This conclusion is in agreement with the previous studies reported in the literature review section of this work. The
Interviewees have reiterated that (not included in the tables) the amount and degree of changes depend on the nature of the work, its complexity and its extent in addition to the level of experience of concerned people. Projects that have repetitive design and detail such as standardized schools, clinics, social houses and apartments' blocks experience less amount and degree of changes compared to the non-repetitive projects especially the ones that have relatively complicated detail and have high standard finishes.

Table 6.1 :
Question No. Interviewee No. 1 Interviewee No. 2 Interviewee No. 3 Interviewee No. 4
1. Do you encounter
design changes on
projects you carry
out? How often?
Yes, almost on all projects
Yes, very often, 5 to 6 changes per project
Yes, very often Yes, very often
2. Why design
changes occur?
Clients make changes, clients do not get involve at early stage, lack of co-ordination between design members, clients sometimes want to save money or to do the work within budget estimates, modify the design to suit site conditions, contractors need to get different construction methods specially on design and build projects
Scope in many cases is not well defined, clients change the design, un-expected site conditions
Clients change the requirements, scope of work is not well defined by both the client and the consultant, different interpretation to contract documents and clauses
Clients introduce changes when initial brief is not clear, intial requirement change, financial availability change (decrease or increase) and change of material.
Consultants introduce changes to enhance the quality of design and due to availability/introduction of new material
3. What is the most
common cause of
design changes?
4. Who causes esign
changes?
5. Who is the most
common source of
design changes
Change on scope of work by clients
Clients, Contractors and Design
Members
Unclear scope of work
Clients and/or his representative
Change of requirements caused by clients
Change of brief by the client
Clients and governments authorities
Clients, statutory authorities and very seldom by consultants
Clients Clients Clients Clients
6. What are the
impacts of design
changes on
projects?
Delay the design and the progress at site, lead to frustration and build bad atmosphere, increase the fee, quality is effected and increase the chance for mistakes
Increase the fee and time, loss of design productivity, disturb the design plan and procurement of resources
Delay the production of design, increase the fee of the design and increase the chance of disputes
Delay the progress, increase/decrease in expenditure, change in contracts and improvement in finished project

Table 6.1 :
Question No. Interviewee No. 1 Interviewee No. 2 Interviewee No. 3 Interviewee No. 4
7. Do contract
provide guidelines
to cover the fee
of design changes?
Yes but not very effective Yes
8. What method are
you using to
assess the fee of
design changes?
9. Do you encounter
disputes due to
changes?
At early stage or new work a lump sum method and negotiation, at later stage for modification manhour method
Man-hours rate plus office running cost plus paper cost and 20% profit
Yes, very often Yes
No clear methods in most of the contracts. This lead to production of our change control form
Yes under modify design services section
Negotiation before the execution of the work, for some client negotiation after the execution.
Normally we get paid after assessing additional man-hours input required to conduct design changes.
Yes, always Yes
10. Why disputes
occur?
Due to lack of trust. Clients always question the claimed design time and sometimes ask for un-reasonable justification
Due to different interpretation of the contract between the client, contractor and consultant
Clients do not accept the charges set by the consultant without a comprehensive justification
Claimed amount is always disputed by the clients and they do not accept the fact that changes are introduced due to incomplete design brief and clients feel that consultant’s rate to modify the design is much higher than the actual project rate.
11. How do you
solve the
disputes?
Mostly by negotiation, one case settled by court
By mature discussion and negotiation
Negotiation and the intention to settle the payments quickly to keep good relation with clients
Disputes are normally not solved, but the consultants have to accept the decision by the clients which may not be fair.

Table 6.2
:
Question No. Interviewee No. 1
1. Do you encounter
design changes on
projects you carry
out? How often?
Yes, in every project
Interviewee No. 2
Yes, very often
Interviewee No. 3
Yes, always
Interviewee No. 4
Yes, very often
2. Why design
changes occur?
Clients change the function of the projects when they see them in reality. In many cases, specially for fast track projects, no sufficient detail is provided at the initial construction stage and due to financial reasons of the clients
Clients change their mind, to meet the authority regulations, to rectify the improper design, to suit site conditions and to use new material
Incomplete design at starting construction, modification or changes to the intended use of projects, clients’ desire for something better, end users need changes, new technology/material and contract build-ability benefit
Change of requirement by client and consultant, incomplete design when contract awarded, unforeseen site conditions, lack of co-ordination, change of authority regulations, early completion requirement and value engineering to save cost and money
3. What is the most
common cause of
design changes?
4. Who causes
design changes?
5. Who is the most
common source of
design changes
Complete design is not provided at the initial construction stage
Clients, Designers and ontractors to use alternative material
Clients’ oriented changes
Clients and Consultants
Incomplete design at start of construction
Clients (60%), Consultants (30%),
Contractor (20%)
6. What are the
impacts of design
changes on
projects?
Alteration and re-work, loss of efficiency and productivity, extension of time, increase the cost, lead to frustration and strain the relation with others
Increase the cost and time, increase labor cost, increase the frustration, loss of efficiency, extra waste of material
Extension of time, extra waste of material, increase indirect loss of time and money, quality drops if not programmed well, increase direct cost ( may be save money), resources of labor and material get effected
Lack of co-ordination specially for fast track projects
Clients, Contractors for design & build projects and Design
Members
Major effect on time and cost, result on re-work, loss of productivity and momentum and increase the chance for frustration

Table 6.2 :
Question No. Interviewee No. 1
7. Do contract
provide guidelines
to cover the fee
of design changes?
Yes, for the benefit of the clients
8. What method are
you using to assess
the fee of design
changes?
Not applicable to answer
9. Do you encounter
disputes due to
changes?
Yes, very often
Interviewee No. 2
Yes
For design and build projects, manhours rates
For sub-consulting works, manhours basis but always look to the original design fees basis
Yes
Interviewee No. 3
Sometimes yes
Yes, always
Interviewee No. 4
Yes, but not in details
Not answered, it is not applicable
Yes
10. Why disputes
occur?
Clients are not willing to give fair compensation for the changes, not easily accepting the impact on schedule, due to natural distress and each side try to defends his interest
Clients always want to pay less than the actual claims and they do not accept easily the extension of time cause by the changes
Not getting the right compensation, the sub-consultants maximize their profit, extension of time is not always accepted and the effect of the changes is under estimated by both clients and consultants
Clients do not accept the indirect cost and time caused by the changes and the contractors mostly not getting the claimed amount
11. How do you
solve the
disputes?
First by negotiation and if not succeeded possibly by court
Negotiation and discussion Negotiation and arbitration
Refer to contract clauses, negotiation and sometimes arbitration

Question No.
1. Do you encounter
design changes on
projects you carry
out? How often?
Interviewee No. 1
Table 6.3 :
Interviewee No. 2 Interviewee No. 3
Yes, very often Yes, in many cases yes, very minor due to the nature of our projects
Interviewee No. 4
Yes almost to all projects
2. Why design
changes occur?
Change client’s requirements, different site condition, incomplete design information and for build-ability reasons
Problems with site conditions, introduction of new requirement and new technology
To implement new ideas and new technology, to improve the initial design and to adopt better specifications
Desire to get better planning, improper design detail, insufficient site investigation, and use of alternative construction material/detail to save time and money
3. What is the most
common cause of
design changes?
Change of client’s requirements Introduction of new requirements Improvement to the original design To get better planning
4. Who causes
design changes?
5. Who is the most
common source of
design changes
6. What are the
impacts of design
changes on
projects?
Clients (60%), Consultants (30%),
Contractors (10%)
Clients Clients Clients Clients
Delay on the completion, cost overrun, loss of productivity, decrease in moral and enthusiasm and increase the waste of material/resources implications
Clients
Delay the projects and cost
Clients, contractors and sometimes consultants
Cost increase dramatically, causes major delay, increase the working load of the stuff and increase the waste of material
Clients and contractors
Projects get delay, cost overrun, increase the chance of disputes, lead to frustration to both contractor and client and reduce the quality of the work due to extra speed to meet the deadlines

Table 6.3 :
Question No. Interviewee No. 1 Interviewee No. 2 Interviewee No. 3
7. Do contract
provide guidelines
to cover the fee
of design changes?
Yes
Yes usually some clauses in the contracts
8. What method are
you using to
assess the fee of
design changes?
Time sheet method from the consultant to record the manhours and a lump sum fee method to do the changes for negotiation and agree as a lump sum without further justification
Percentage of construction cost of the modified parts and man-hour method
9. Do you encounter
disputes due to
changes?
10. Why disputes
occur?
Consultants submit excessive man-hours, lack of appreciation and understanding on the actual resources require to carry out the design changes, lack of on time notification by the consultants on the fee of the changes and lack of proper back up for the claims
Fee always come high when compared to the original design fee
Yes, but debatable
No, because the changes are negligible
No disputes
11. How do you
solve the
disputes?
Normally by negotiation Negotiation and discussion By discussion and negotiation
Interviewee No. 4
Yes, different guidelines to different projects
Yes, sometimes
Fee of the changes comes high compared to the original fee, difficult to quantify the changes and evaluate their fee, miss understanding the actual scope of work and different interpretation to the contract clauses
By negotiation with reference to contract documents

Table 6.4 :
1. Do you encounter
design changes on
projects you carry
out? How often?
Yes, very often Yes, always
Yes
2. Why design
changes occur?
Clients modify the original design to suit their new requirements, clients sometimes want to save money, scopes in many cases are not well defined, lack of co-ordination between design members, different interpretation to contract documents and clauses, consultants introduce changes to enhance the quality of design and due to availability/ introduction of new material
Clients change the function of the projects when they see them in reality, clients’ desire for something better, end users need changes, no sufficient detail is provided at the initial construction stage, lack of co-ordination, financial reasons, early completion requirements, change of authority regulations, result of value engineering to save money and/or time, to rectify the design mistakes, to suit site conditions and to use new material/technology
Introduction of new requirements, modification to the original design as part of design development process and design improvement, desire to use better specification and new material/ technology, insufficient site investigations, improper design details, site conditions problems and for alternative construction detail to save time and or money
3. What is the most
common cause of
design changes?
Clients’ oriented changes
4. Who causes
design changes?
Clients, Contractors, Design Members,
Government Authorities and sometimes
Consultants
Incomplete design at initial construction stage
Clients, Consultants and Contractors
Introduction of new requirements
Clients, Consultants and Contractors
5. Who is the most
common source of
design changes
Clients Clients Clients

Table 6.4
:
Question No. Consultants Contractors Clients
6. What are the
impacts of design
changes on
projects?
Delay the design, delay progress at site and completion time of projects, increase the cost, quality is effected, disturb the design plan and procurement of resources, increase the chance of mistakes, loss of productivity, lead to frustration, build up bad atmosphere and increase the chance of disputes
7. Do contract
provide guidelines
to cover the fee
of design changes?
8. What method are
you using to
assess the fee of
design changes?
9. Do you encounter
disputes due to
changes?
Yes, but not easy to implement
Lump-sump method, man-hours method and negotiation
Yes, very often
10. Why disputes
occur?
Increase the cost and time, alteration and rework, resources of labor and material get effected, loss of efficiency and productivity, extra waste of material, quality drops if not programmed well, increase the frustration, and strain the relation with the others
Yes
For design and build projects or subconsulting works, man-hours rates. Two contractors did not answer this question
Yes
Most of the times claimed amount is disputed by the clients and they ask for unreasonable justification, lack of trust, different interpretation of the contract clauses and the clients feel that consultants’ rate to modify the design is much higher than the original project rate
Clients tend to pay less than the actual claims and not easy accept the impact on schedule and indirect construction cost
Delay the projects, cost overrun, loss of productivity, increase the paperwork, increase the working load of the stuff, decrease in moral and enthusiasm and increase the waste of material/resources
Yes
Man-hours time sheets, lump sum method, percentage of construction cost of the modified parts
Yes, always
Fee of the design changes always comes high when compared to the original design fee, difficulties to assess the claimed man-hours, lack of appreciation and understanding on the actual resources require to carry out the design changes, lack of on time notification by the consultants on the fee of the changes and lack of proper back up for the claims
11. How do you
solve the
disputes?
Negotiation and mature discussion Negotiation, discussion and arbitration Negotiation and discussion

118
6.2.3 The Causes and Sources of the Design Changes
Referring to the results of the interviews as presented in Tables 6.1 to Table
6.4, the reasons for design changes as perceived by the interviewees include changes on scope of works and normally initiated by clients. This is the most common source of design changes. Many clients have no sufficient ability to visualize the proposed works from detailed drawings until they see them in reality. If the work does not satisfy their need, they introduce changes on the completed parts. Many ideas and new requirements come at later stages that clients are eager to agree to it.
Changing the specification by clients is not unusual in the construction industry in order to enhance the quality of the work and extend its performance. Clients’ capacity to meet the financial obligations to the projects plays an essential part to achieve a successful completion. There are many cases where clients get difficulty to meet these obligations. As a result they tend to reduce the cost of their projects by modifying the scope of work, carrying out value engineering, using an alternative material, adopting different construction methods and limiting the work to be within the budget estimate.
Lack of co-ordination between designs members at the initial stage also contributes changes to projects. Co-ordination is important and should start at the initial design stage where many important decisions take place at this stage. Buildability and conformity of the elements from different disciplines totally depend on the level of co-ordination between the design members of the disciplines.
Unclear scope of work is also a common source of design changes especially for fast track projects. To save time, there are cases where the construction work starts before the completion of the design. The contractors submit tenders according to the available information to them. At later stage, they might get unexpected detail that may require different skills and resources than the planned ones which could have cost implications. In addition, the contractors may get hold because of unavailability of the details when they are needed.
Changes also caused by unexpected site conditions. This is due to improper site investigation and improper feasibility study at the proposed site. It is important

119 to carry out at early design stage a comprehensive site survey including topographical study and soil investigation. It is equally important to highlight any site restrictions and to give details of any existing structures and facilities along with the available accesses to site and allocated area of storing the construction material. .
6.2.4 The Impact of the Design Changes
While consultants, contracts and clients spend great effort to ensure the completion of the work within the allocated time, cost and good quality , design changes are no doubt deviate these essential goals. It can be noted from the respondents of question number 6 in Table 6.4 that changes cause major delay on the planned completion time because they disturb the planning of material and resources and the completed parts require re-work. The extent of the delay will have great cost effect due to the extension of time require to manage the site and to supervise the works as well as due to extra waste of material and resources. In addition, productivity, efficiency and momentum get affected and slow down over all progress of the work. Changes also increase the cost of the projects. . Furthermore, there is a common interest among professionals in the construction industry to build good relation with each other, and to work in harmony to achieve a successful projects, design changes are yet build bad atmosphere, lead to frustration and strain with others, decrease in moral and enthusiasm and increase the chances for disputes.
6.2.5
Existing Methods for Assessing the Fee of Design Changes and their Limitations
Although provisions are normally including in the design agreements either standardized clauses in an attempt to assess the fee of design changes when they occur, there is no acceptable results from adopting any of the existing methods. The result of the interviews revealed that the most widely method used by professionals in Oman is the man-hours method. This method if adopted is based on trust between

120 the consultants and their clients. The consultants keep records for the actual timing that for certain changes or claim the predicted time required for carrying out the changes. From the consultants' point of view, it is not always easy to keep track the actual hours spent and managing them. Even though the consultants usually base their claims as an actual times, there are in many cases approximates especially for large amount of changes. From the clients' point of view, the hour unit rate is typically high compared to the fee of the original design. Clients tend not to negotiate at the tender stage on this high unit rates and mainly concentrate on the design fees. Secondly, clients feel that the claimed hours are over-estimated and hence disputed. They ask for further justification which might not be readily available with the consultants. Disputes arise from this method due firstly to the difficulties to assess the claimed man-hours by clients and secondly lack of proper back up for the claims by the consultants.
A second recognized method in practice that used to assess the fee of the changes is the percentage of construction cost. This is an old method and proved to be not very effective as explained by others in literature review (refer to chapter 3, section 3.6.5). Nevertheless, the fee of the changes as a percentage of construction fee of the portion under modification is totally a function of the cost of construction material used, the grade of the contractor and the construction rates. As an example, the construction cost of high strength, special concrete structural elements with stainless steel that carried out by excellent contractor is very high compared to the one with low strength normal concrete, normal steel while the time require to do the design is same. If this method of assessment is used, the fee of the changes no doubt is very high.
The third method that people are using is a lump-sump method. This is a traditional method and is based on negotiation. The main disadvantage of this method is the chance that people do not agree with the fee. Many consultants do not accept to carry out the design changes prior to mature agreement which may result in delaying the work. In addition, there is a tendency that the fee of design changes becomes high and clients might be forced to accept the fee in favour to progress the work.

121
6.3 Case Studies Results
Three case studies have been considered for this research work. They were all from the Sultanate of Oman. The intention for the case studies is to provide actual examples on the negative parts of the design changes especially on cost and time. In additions they were used to identify the methods that being used by the professionals in the construction industry. A detailed methodology for the case studies is given in
Chapter 5.
6.3.1 Case Study One
The design phase of this project initiated on April 1994 and the construction of the whole project completed on March 2001. It consists of three main complex buildings with basements and/or ground floors. It is unique in its architectural features, interior finishes and its large scale structural elements. The complex is enclosed by boundary wall and four main entrance gates. Four approach roads connect the development to the main surrounding roads. Outside courtyard is rich on landscaping and many different agricultural plantations. The design was carried out by an international consulting engineering firm and the consultancy agreement was to cover the full design and supervision of all parts mentioned above. This included design and supervision of all architectural, structural, landscaping, mechanical and electrical works but excluded the interior design part. Table 6.5 highlights the main sources, causes and the fee of the design changes for case study one.

122
Table 6.5 : Case Study One - Causes, Sources and Fee of Design Changes
Var
No.
Date of
Design
Changes
1 25/12/95
2 27/01/96
3 01/03/96
4 21/05/96
5 07/06/96
6 14/09/06
7 03/11/96
8 27/12/96
9 21/03/97
10 19/04/97
11 21/07/97
12 05/09/97
13 28/12/98
14 30/03/99
15 25/12/99
16 17/06/2000
Main Causes
Modifications to the design
Introduction of new work
Introduction of new work
Modifications to the designs
Modifications to the design
Lack of coordination
Lack of coordination
Improper site investigation
Introduction of new work
Introduction of new work
Introduction of new work
Modifications to the design
Modifications to the design
Introduction of new work
Lack of coordination
Introduction of new work
Main Sources
Interior
Designer
Interior
Designer
Sub-
Consultant
Interior
Designer
Fee of the
Changes,
USD
% of
Original
Fee
6,269 0.67
32,901 3.52
27,720 2.97
25,648 2.75
Total 1,284,519 137.53
Notes:
1. Original design fee USD$ 934,003 (Architecture, Structure, M&E and
Landscaping, exclusive Interior Design and Supervision
2. Costs were converted from Rial Omani to USD$ (1 Rial = 2.5907 USD$ as on
June 2004)

123
In the above table, new work is the work that originally was not part of the initial scope of the work. This includes extension of the buildings, introduction of new buildings, introduction of new elements such as boundary walls, gates, new facilities etc. Modification to the design, on the other hand, consists of re-arranging the structural elements to suite new conditions. These new conditions either caused by new architectural arrangements or to suite other design requirement such the one for the air conditioning systems or for the interior design.
6.3.2 Case Study Two
The initial structural design part of this project started on November 1996 and the construction of the structural work completed on October 1999. The total construction completed on March 2001. This project has the following main elements:
ƒ
Three main concrete buildings with basements and ground floors;
ƒ
Seven secondary concrete buildings of one floor each;
ƒ
Main and secondary boundary walls with entrance gates; and
ƒ Service roads and landscaping works
The main complex buildings have many distinctive architectural features both internally and externally with high standard interior finishes while the secondary buildings have very basic finishes without interior design works. The structural design and supervision of the project was given to an international consulting firm while all other design elements such as architectural, interior, landscaping, mechanical and electrical works were designed in house by well established client's own design office. Table 6.6 shows the main sources, causes and the fee of the design changes for case study two.

124
Table 6.6 : Case Study Two - Causes, Sources and Fee of Design changes
Var.
No.
Date of
Design
Changes
1 27/01/97
Main Causes Main Sources
Fee of the
Changes,
USD
% of
Original
Fee
2 28/07/97
3 02/08/97
4 15/10/97
5 23/10/97
6 14/11/97
7 27/11/97
8 04/01/98
9 23/01/98
Extra soil investigations
Modifications to the design
Modifications to the design
Extra soil investigations
Introduction of new works
Introduction of new works
Lack of coordination
Introduction of new works
Introduction of new works
Structural
Engineer
Service
Engineer
31,088 14.81
1,904 0.91
11 12/03/98
12 16/04/98
13 03/06/98
14 25/07/98
15 07/08/98
16 14/02/99
17 01/05/99
Introduction of new work
Modifications to the design
Modifications to the design
Modifications to the design
Modifications to the design
Introduction of new works
Lack of coordination
Interior
Designer
1,927 0.92
Total 398,266 189.79
Notes:
1. Original structural design fee USD$ 209,846
2. Fees were converted from Rial Omani to USD$ (1 Rial = 2.5907 USD$ as on
Jan.2004

125
Due to increase number of design changes for the project in case study two and their associated fee, the client have made an attempt to improve the condition of the claims. He has requested the consultant to provide full time structural engineer and a draftsman in a monthly rate basis agreement initially for three months and could be extended if deemed necessary to carry out the design changes. It was a risk on the client because it was difficult to predict the amount of the changes that may take place in the future but his decision was based on his expectation, experience on the project, and the fee of past changes that already claimed by the consultant which all turned up to be in favour of this new approach of controlling the extra fee of the changes. Nevertheless, there was noticeable reduction in number of claims after the implementation of this approach except for changes that were caused by clients' instruction to carry out new works which were charged separately.
6.3.3 Case Study Three construction of the structural work completed on May 2004. This project consists of the following parts:
The structural design stage of this project started on mid May 2000 and the
ƒ
Main complex concrete buildings with basements and three floors;
ƒ
Four secondary buildings of one to two floors without basements;
ƒ
Boundary wall with entrance gates along it; and
ƒ Service roads and landscaping works
The main buildings have various degrees of complexity due to their architectural planning and detail. The secondary buildings are also complicated in nature but less than the main buildings. Similar to the project in case study two, the structural design and supervision carried out by international consulting firm while all other parts designed by client's own design office and supervised by others.
For the project in case study three, they are clauses in the contract documents that classify the design changes into major and minor. In these classifications, major

126 changes are the ones that caused by expanding the structure either horizontal by introducing extensions to the original planning or vertically by adding more floors or increasing the original height of the buildings. In addition, adding new works that have not been part of the original contract agreement have been considered to be of major variation. On the other hand, minor changes are the ones within the original design without increasing the structures or adding new works which in turn to be considered part of design developments. Consultants have been requested at the tender stage to include in their tender submission fees, if they consider it necessary, to cover all minor design changes. Hence, they have requested to take note that no claims would be accepted for minor design changes.
The appointed consultant for the project in case study no. 3 have included in his tender submission one full time structural engineer and one full time draftsman to cover what is meant to be minor design changes for the duration of the design period.
Any minor changes above the capacity of the allocated staff would be considered a variation to the original scope. He qualified his submission as above which in the end was accepted by the client. Table 6.7 shows the main sources, causes and the fee of the design changes for case study three.
6.3.4 Causes of Design Changes
The main causes as identified from the three case studies and were shown in
Table 6.5, Table 6.6 and Table 6.7 are the following:
•
Modifications to the original design;
•
Introduction of new works ;
•
Lack of co-ordination between design members;
•
Un-expected site conditions; and
•
Alternatives construction methods

127
Table 6.7 : Case Study Three - Causes, Sources and Fee of Design Changes
Var.
No.
Date of
Design
Changes
1 27/11/01
2 12/12/01
3 21/12/01
4 22/01/02
5 27/04/02
Main Causes Main Sources
Fee of the
Changes,
USD
Modifications to the design
Modifications to the design
Lack of coordination
Modifications to the design
Modifications to the design
Interior
Designer
% of
Original
Fee
10,933 2.48
7 12/05/02
8 23/05/02
10 03/06/02
11 17/11/02
12 16/02/03
13 25/05/03
14 07/06/03
15 12/11/03
Un-expected site condition
Lack of coordination
Structural
Engineer
Service
Engineer
5,575 1.27
5,032 1.14 of 5,329
Un-adequate
Design
Modifications to the design
Lack of coordination
Lack of coordination
Alternative construction method
Addition of new work
Interior
Designer
Interior
Designer
2,528 0.57
8,938 2.03
Contractor 1,337 0.30
Notes:
1. Original structural design fee USD 440,414 excluding supervision
2. Fees were converted from Rial Omani to USD (1 Rial = 2.5907 USD as on June
2004)

128
These causes are in-line with the causes that have been identified in the literature review and the interview parts of this research work. However, the following causes that have been identified in both the literature review and in the interviews have not contributed to the design changes in the three case studies:
•
Clients' financial difficulties;
•
Substitution of materials;
•
Conflict between contract documents;
•
Results of value engineering process;
•
Adoption of new technology;
•
Rectification of defective works;
•
Requirements for safety measure;
•
Changes to meet new governments regulations; and
•
Unclear contract clauses
One of possible reasons for limiting the causes of design changes to the ones mentioned above is that, only major design changes or new works that have reasonable fee effect have been considered as valid design changes claims. There were possibly many other design changes of minor impacts in which some of them may fall under the causes that have been identified in the literature review and the interview parts have been, instead, considered part of design development and hence no claims from such changes. On the main time, and as mentioned in the previous section, many design changes have been covered by complementary agreements or covered under the original contracts documents. As a result, the majority of the changes are Clients' oriented changes with few reported to be due to lack of coordination and contractors' sourced changes.
6.3.5 Sources of Design Changes
Similar to the result of the interviews carried out in this research, Table 6.5,
Table 6.6 and Table 6.7 revealed that clients are the most common source of design

129 changes in the Sultanate of Oman construction industry beside design members being the next and the contractors are the least producers of the changes. This can be contributed to the fact that the details of the projects were not completed at the time of design tender stage. Due to this, many new ideas from the clients came up at later stage which in turn leads to the increase number of clients' oriented changes.
6.3.6 Impacts of Design Changes on Cost
Table 6.8 below summarises the impacts on fee for both design and supervision phases. Increase in design fee is normally a factor of the size and complexity of the projects, the clear definition of the scope at the tender stage and the availability of initial investigation of proposed sites. As it can be seen from
Table 6.8 the percentage of paid amount for design is less than the claimed amount.
The reasons being for this are that the consultants have used for most of their claims man-hours basis (other claims were based on lumps sums). These man-hours were disputed by the clients and in turn further justifications were practically not possible.
The reduction on design fee was a result of lack of trust between the consultants and their clients on the estimated time. Furthermore, it was difficult for the clients to evaluate the claimed man-hours because no recognizable method is available for such evaluation. Due to these facts, both clients and their consultants most probably went through mature discussions and negotiations which resulted in an agreement on the coats of the changes. For the fee of supervision, there were no disputes arises because the monthly rate per person were well defined in the contracts and the supervision times could not be easily disputed.

130
Table 6.8 : Case Studies - Impact on Cost
Case Study No.
Original Design Fee
Fee of the Changes
Final Design Fee
Increase in Design Fee
Paid Amount for Final
Design
% Paid for Final Design
Original Supervision Fee
Final Supervision Fee
Claimed Amount for
Supervision
Increase in Supervision Fee
Paid Amount for Supervision
% Paid for Supervision
1
USD$ 934,003
USD$
1,284,519
USD$
2,218,522
137.5%
USD$
1,863,550
84.0%
2
USD$ 209,846
USD$ 398,266
USD$ 608,112
189.8%
USD$ 473,070
77.8%
USD$ 704,598 USD$ 145,078
USD$
2,707,768
284.3%
USD$
2,707,768
USD$
2,707,768
100%
USD$ 239,365
65.0%
USD$ 239,365
USD$ 239,365
100%
6.3.7 Impacts of Design Changes on Schedule
The impacts on schedule for the three case studies are given in table 6.9 below.
The amount of the changes does not only delay the progress of the design but also delay the construction and extend the supervision time. Similar factors that have been mentioned in previous section to cause design fee overrun are also cause extension to the original programmes. Although design changes no doubt cause delay on the progress of construction works, the total delay on construction cannot be totally contributed to design changes. Other factors such as contracts' or clients' oriented reasons may have negative effects as well in the construction programmes. The supervision time is a factor of construction time. Any construction delay would lead to extension on supervision time. Hence the percentage of delay on construction and supervision shown in Table 6.9 might be partially contributed to design changes.
79.0%
USD$
568,290
USD$
909,264
60.0%
USD$
909,264
USD$
909,264
100%
3
USD$
440,414
USD$
243,127
USD$
683,541
55.2%
USD$
540,000

131
However, it can be seen from Table 6.8 and Table 6.9 that when time overruns for a project, design and supervision fees for that project increase accordingly.
Table 6.9 : Case Studies - Impact on Schedule
Case Study No.
Original Design Period
Actual Design Period
1
321 Days
947 Days
2
104 Days
608 Days
3
290 Days
715 Days
Increase in Design Time
Original Supervision Period
Actual Supervision Period
Increase in Supervision Time
Original Construction Period
Actual Construction Period
195.0%
34 Months
77 Months
126.5%
34 Months
75 Months
484.6%
24 Months
31 Months
29.2%
24 Months
29 Months
146.5%
30 Months
48 Months
60.0%
29 Months
42 Months
Increase in Construction Time 120.6% 20.8% 44.8%
.
6.3.8 Existing Methods for Assessing the Structural Design Changes
Only two methods have been used for the claims that have been submitted for extra charges due to design changes. These two methods are:
•
Man-Hours Method; and
•
Lump-Sum Method
In general, changes that have caused by addition of new works were based on the lump-sum method where all other claims are based on man-hours methods. It has been noticed from the three case studies that by using the Man-Hours method, the consultants have based their claims on an estimated time rather than an actual one.
Furthermore, consultants tend not to record the time at the execution of the changes, instead, they estimate the time when the design changes are completed. At this stage, the time is purely based on approximations.

132
6.4
Questionnaire Survey Result
The questionnaire survey has been conducted to establish the significant level for each factor under investigation as perceived by the clients, the consultants the contractors working in the construction industry in The Sultanate of Oman. Detailed methodology for the questionnaire survey has been given in chapter 5 (Research
Methodology chapter). The following sections highlight the findings of the questionnaire survey.
6.4.1 Causes of Design Changes Due to Clients
The objective of conducting the analysis for this section is to establish category and ranking for each cause of clients’ oriented design changes according to their significant level as perceived by clients, consultants and contractors. There are seven possible causes have been identified form literature searching, interviews with professionals in the construction industry and pilot study that have been conducted for this research work and reported in previous parts. Main Scores, MS , and
Rankings, R , for each cause are presented in Table 6.10. As it can be seen from this table, clients, consultants and contractors “mostly agreed” that clients are likely to
“modify the original design” and this factor has been considered the most common cause of clients’ oriented design changes. Consequently, this factor has been assigned the highest rank among other causes with a weighted average mean score of
4.175. In addition, contractors have “mostly agreed” to give the second highest rank to the cause wherein clients are likely to “add new works/scopes” with a weighted average mean score of 4.037 as perceived by the three participated groups.

133
Table 6.10 : Main Scores ( MS ) and Ranks ( R ) for Causes of Design Changes Due to Clients
Cause(s)
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R a) Additions of new works/ scopes (not part of original scope)
4.273 2 3.778 2 4.000 1 4.037 2 b) Omission of works/ scopes (reduction on original scopes)
3.000 3 2.333 7 2.857 4 2.741 6 c) Modifications to the original design (changes within the original scope)
4.454 1 3.889 1 4.105 1 4.175 1 d) Not clear initial design brief (e.g. the extent of the scopes, requirements, details etc.)
2.909 4 3.333 3 3.571 3 3.222 3 e) Desire to use alternative material/new technology
(may require different details and co-ordination with suppliers) f) Desire to use better specification (e.g. to extend the life of the structure or for better performance etc., may require different design detail) g) Insufficient background of proposed site (e.g. possibility of underground facilities, previous structures, previous site condition etc.)
2.818 5
2.818 6
2.400 7
3.000 4 2.286 7 2.741 5
2.778 5 2.714 5 2.778 4
2.667 6 2.714 5 2.570 7

134
Furthermore, consultants have “slightly agreed” in the opinion that clients tend to originate design changes through “reducing original scopes”. Subsequently, consultants have put this factor in the lowest rank of 7 with mean score of 2.333.
Clients and contractors, on the other hand, have “agreed in average” to give this factor more weight as a cause of clients’ oriented design changes through their mean scores of 3.000 (ranked 3 out of 7) and 2.857 (ranked 4 out of 7) respectively. .
The participated groups have “mostly agreed” not to consider the factor in which clients tend to provide “insufficient background for their proposed sites” as a main cause of clients’ oriented design changes. This factor may include the detail for underground facilities, previous structures, and previous site conditions etc, which in turn reduce the chances for modifying the design to cope for such obstacles. This factor has been given the lowest weighted average mean score of 2.570 which indicates it low level of significant compared to other factors. The result of the statistical test that has been conducted on this group of clients’ oriented design changes is shown in Table 6.11 below. It is clear from this table that at 95% confidence level, clients versus consultants and consultants versus contractors did not have significant agreement in the ranking since the null hypothesis H
0
is accepted for these groups. Hence; the null hypothesis: reject H
0 if -t st
> t cal
> + t st
. On the other hand, clients versus contractors did have significant agreement in the ranking.
Thus an alternative hypothesis H
1
is accepted.
Table 6.11 : Test for Agreement on the Ranking for Causes of Design Changes Due to Clients
Group
Clients and Consultants
Spearman’s coeff. Rho. (r s
) t-statistics
(Calculated) t-statistics
(From ttable)
Reject
H
0
0.643 1.877 No
Clients and Contractors 0.786 2.843 2.571 Yes
Consultants and Contractors 0.643 1.877 No

135
6.4.2 Causes of Design Changes Due to Consultants
There are many reasons wherein consulting engineers introduce design changes which may require at later stage modifications to the original design and/or constructed works. Five causes have been identified to be of common occurrence as reasons for consultants’ oriented design changes. These causes are shown in Table
6.12 below along with their Main Scores, MS, and Rankings, R , for each cause as perceived by the participated groups in the questionnaire survey for this study.
It is clear from Table 6.12 that “inconsistent information in drawings” such as conflicts between structural and architectural details is the most common cause of consulting engineers design changes. Clients have “agreed in average” and contractors have “mostly agreed” to give this cause the highest rank with mean scores of 3.364 and 4.000 respectively. In spite of these high scores, consultants considered the possibility of this factor to take place comes in the “average range” with mean score of 2.667 but happened to be in the second highest rank.
Furthermore, there is an agreement among the respondents that “discrepancy between contract documents”, for example between drawings, specification and Bill of
Quantities, comes in the second highest rank yet in the “average range” as well.
It is worth to notice from the above table that unlike clients and contractors, consultants have given a highest score for the factor related to the “insufficient detail of existing site conditions” such as clashes with underground facilities, clashes with adjacent structures, flooding condition at site, etc. To this extent, the consultants have believed more on the excessive changes as a result of the above factor. This high score might be contributed to the fact that consultants expect clients to provide such information either through carrying out site investigation or through providing records/documentations for the proposed site. In this regard, clients may under estimate the need for these requirements or may not be in a position to provide such information. Consultants, on the other hand, normally do not consider these tasks parts of their responsibility unless there is a specific request from clients to carry out such services.

136
Table 6.12 : Main Scores ( MS ) and Ranks ( R ) for Causes of Design Changes Due to Consultants
Cause(s)
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R a) Improper design /part of design improvement (e.g. to rectify design mistakes, to adopt better detailing, to simplify the design for easy construction etc.)
2.909 3 2.556 4 2.571 3 2.704 4 b) Inconsistent information in drawings (e.g. structural detail does not matching architectural detail etc.) c) Discrepancy between contracts documents (e.g. drawings/ specification,
Bill of Quantities etc.)
3.364 1 2.667 2 4.000 1 3.297 1
3.091 2 2.667 2 2.857 2 2.889 2 d) Lack of/insufficient geotechnical investigation or wrong interpretation of the findings (e.g. un-expected rock layers, loose soil, high water table etc.)
2.545 4 2.444 5 1.857 5 2.333 5 e) Insufficient detail of existing site condition
(e.g. clashes with underground facilities, clashes with adjacent structures, flooding condition at site, etc.)
2.545 4 3.111 1 2.571 3 2.740 3
Furthermore, the participated groups “slightly agreed” on the factor associated with “lack of/insufficient geotechnical investigation or wrong interpretation of the findings” (e.g. un-expected rock layers, loose soil, high water table etc.) as a cause of consultants’ originated design changes. The reason behind

137 this low score for this factor might be related to the common practice in the construction industry in which soil investigation normally conducted for almost all major projects and there is a general trend on ability of the designers to interpret the findings correctly.
Table 6.13 shows the statistical test on this group of consultants’ oriented design changes. At 95% confidence level, clients versus consultants and consultants versus contractors did not agree significantly in the ranking of the factors. Hence, the null hypothesis H
0
for these two groups is accepted since the null hypothesis is to reject H
0 if -t st
> t cal
> + t st
.. For clients versus contractors group, the Spearman’s coefficient ratio, r s is 0.900 which indicates a strong correlation in the ranking between both groups of respondents on the factors for this group of causes since the r s
is close to a unity. This concludes that there is a significant agreement in the ranking so that the null hypothesis H
0
is rejected and the alternative hypothesis H
1
is accepted for this group.
Table 6.13
Test for Agreement on the Ranking for Causes of Design Changes
Due to Consultants
Group
Clients and Consultants
Spearman’s coeff. rho. (r s
) t-statistics
(Calculated) t-statistics
(From ttable)
0.400 0.756
Reject
H
0
No
Clients and Contractors 0.900 3.576 3.182 Yes
Consultants and Contractors 0.700 1.698 No
6.4.3 Causes of Design Changes Due to Contractors
The literature review, the interviews with professional in the construction industry and the pilot study which all conducted at early stage of this research work revealed many causes of contractors’ originated design changes. These causes are shown in Table 6.14 below along with their Mean Scores, MS , and Rankings, R , for each cause as viewed by participated clients, consultants and contractors.

138
Table 6.14 : Main Scores ( MS ) and Ranks ( R ) for Causes of Design Changes Due to
Contractors
Possible Cause(s)
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R available 3.000 3 3.444 1 2.143 5 2.926
3 b) To use alternative construction methods to save time c) To use alternative construction methods to save money d) To rectify construction mistakes
2.727 4
3.364 1
3.182 2
3.000 3
2.889 4
3.142 2
3.000 1 2.889
2.857 2 3.074
2.429 3 2.973
4
1
2 e) To improve the quality of works at site
2.182 5 2.444 5 2.400 4 2.184 5
An observation to the above table demonstrates low mean scoring rates for all listed contractors’ oriented design changes ranging from MS 2.143 to MS 3.444.
Hence, all participated clients, consultants and contractors in this questionnaire survey either “slightly agree” or “agree in average” to the causes of the contractors’ oriented design changes. It can be concluded from this result that it is not common cause for contractors to originate design changes.
Clients and contractors have believed more to the fact that contractors may
“use alternative construction methods to save money” so that clients have given this factor the highest rank while contractors put it in the second highest. Contractors, on the other hand, have shown more interest on this factor to save time (highest rank by contractors) rather than saving money. This is true to some extent since contractors always under pressure to finish the work on time. Furthermore, the participated groups were “mostly agreed” that it was not a common cause for contractors to
“improve quality of works at sites” since this factor has been given the lowest rank.
Normally, quality of construction works falls under the responsibility of clients’

139 representatives such as their consultants or specifically appointed quality controllers especially for large scale projects and/or for projects that are extraordinary in nature.
Table 6.15 shows the results of the statistical tests that have been conducted on this group of contractors oriented design changes. As it can be seen from this table, the null hypothesis H
0 is accepted for the three groups which indicates no significant agreements in the ranking of the factors was achieved at 95% level of confidence. In addition, the Spearman’s coefficient ratios, r s for the three groups are close to 0 which implies almost no correlations exist between the scores.
Table 6.15 : Test for Agreement on the Ranking for Causes of Design Changes Due to Contractors
Group
Spearman’s coeff. rho.(r s
) t-statistics
(Calculated) t-statistics
(From ttable)
Reject
H
0
Clients and Consultants 0.300 0.263 No
Clients and Contractors 0.200 0.354 3.182 No
Consultants and Contractors
-0.150 -0.263 No
6.4.4 Sources of Design Changes
Clients, Consulting Engineers, Contractors and specialized Design Members all initiate design changes yet in different magnitudes. Table 6.16 shows the sources that normally originate design changes in the construction industry as well the Mean
Scores, MS , and Rankings, R , for each source. It is observed from Table 6.16 that all participated groups have agreed in the significant level of each source and have given the highest scores for clients to originate design changes and the lowest one for contractors. The respondents have “mostly agreed” in the rank that clients originate design changes more than anybody else in the construction industry and have
“slightly agreed” to consider contractors as originators for design changes. This result is in line with the one in section 6.4.2 where the participated groups have
“mostly agreed” that clients tend to modify the original design and add new works.
The above result also coincides with the conclusion of section 6.4.3 where it was

140 concluded that design changes were not common for contractors. According to the result in the table below, the respondents have considered Clients to be in the first rank to introduce design changes with a Weighted Average ( WA) of 4.445 in which the respondents “mostly agreed” to consider the Clients as a source of design changes, followed by the Design Members such as Interior Designers, Acoustic
Engineers etc., with a WA of 3.741 (they have “mostly agreed” to this source), then the Consulting Engineers with WA of 2.852 ( “agreed in average” ) and finally the
Contractors with WA of 2.111 (“slightly agreed”).
Table 6.16 : Main Scores ( MS ) and Ranks ( R ) for Sources of Design Changes
Possible Sources
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R
4.455 1 4.444 1 4.429 1 4.445
1
3.091 3 2.667 3 2.714 3 2.852
3
2.000 4 2.222 4 2.143 4 2.111 4 d) Design Members (e.g.
Interior Designers,
Acoustic Engineers etc.)
4.091 2 3.000 2 4.143 2 3.741
2
A statistical test was conducted for the group of sources of design changes to test the significant level of agreement between the respondents in which the result is shown in Table 6.17. Since all participated groups agreed in the rankings, the
Spearman coefficient ratios, r s, have a zero value for all groups. As a result, the calculated t-statistics have zero value as well. This result indicates no correlations exist between the groups in the ranking. The null hypothesis H
0
is accepted which confirm that there is no significant agreement in the ranking between the groups.

141
Table 6.17 : Test for Agreement on the Ranking for Sources of Design Changes
Group
Spearman’s coeff. rho.(r s
) t-statistics
(Calculated) t-statistics
(From ttable)
Reject
H
0
Clients and Consultants 0 0 No
Clients and Contractors 0 0 4.302 No
Consultants and Contractors 0 0 No
6.4.5 Impacts of Design Changes
The objective of this section is to establish the level of significance for each factor related to the impacts of design changes aiming to put forward a general knowledge for the professionals in the construction industry on the negative aspects of the design changes so that the avoidable ones could be minimized. The initial stages of this study have exposed number of impacts in which the most common ones are shown in Table 6.18 below along with their mean scores, MS and rankings, R.

142
Table 6.18
: Main Scores ( MS ) and Ranks ( R ) for Impacts of Design Changes
Possible Impact(s)
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R a) Increase design fee 4.454 1 3.778 2 3.286 7 3.926
3 b) Increase construction cost 4.182 2 3.667 4 3.714 6 3.889
5 c) Delay design progress 4.091 3 4.444 1 3.857 5 4.148
1 d) Delay construction progress 4.000 4 3.556 5 4.571 2 4.000
2 e) Increase chances for material waste due to rework operations
3.132 7 3.778 2 4.000 4 6 f) Lead to loss of productivity and efficiency due to interruption and out of sequence works
3.727 5 3.444 6 4.857 1 4 g) Lead to loss of motivation and momentum to re-do the work
3.091 7 3.444 6 4.286 3 7 h) Increase chances for design mistakes
2.636 9 2.556 9 2.429 9 9 i) Decrease quality of works 2.000 10 2.111 10 2.143 10 2.074 10 j) Increase chances for frustration, strain the relation and build-up bad atmosphere among concerned people
3.273 6 3.222 8 3.286 7 8
It is clear from Table 6.18 that the three participated groups did not agree in the most important factor that leads to major impact of design changes. Factor that
“leads to loss of productivity and efficiency due to interruption and out of sequence works” was ranked highest by contractors with a mean score of 4.857 in which contractors have “strongly agreed” on this factor as a most important impact of design changes. The impact on labour productivity due to this factor is a major concern to contractors especially when the changes come at construction stages.

143
Clients have considered the “increase in design fee” is the most important factor among other impacts so that they have placed this impact in the highest rank with a mean score of 4.454 wherein clients in this factor have “mostly agreed” in the ranking. Clients may have influenced to rank this factor the highest by the high fee that the consulting engineers claim for altering the original design. “Delay construction progress” was given the highest rank by consultants with a mean score of 4.444. Hence, consultants have “mostly agreed” in the ranking of this factor.
Although the consultants have no direct impact due to this factor, they have ranked this at highest possibly they have considered their previous experience in which the majority of projects get delayed significantly.
A statistical test has been performed for the factors that are related to the impacts of design changes and the result is shown in Table 6.19. At 95% confidence level, the null hypothesis H
0
is accepted for clients versus consultant group which implies no significant agreement is achieved for the factors of the impacts. The
Spearmans’s coefficient ratio, r s
of 0.733 indicates reasonable correlation to the ranking of the factors. On the other hand, both clients versus contractors and consultants versus contractors did not agree significantly in the ranking since the null hypothesis H
0
is accepted for both groups.
Table 6.19 : Test for Agreement on the Ranking for Impacts of Design Changes
Group
Spearman’s coeff. Rho.(r s
) t-statistics
(Calculated) t-statistics
(From ttable)
Reject
H
0
Clients and Consultants 0.733 3.217 Yes
Clients and Contractors 0.327 1.169 2.306 No
Consultants and Contractors 0.436 1.370 No

144
6.4.6 Corrective Actions and Preventive Measures to Minimize the Avoidable
Design Changes
One of the main objectives of this section is to identify the most significant corrective actions and/or preventive measures that could be recommended to the concerned professionals in the construction industry in an attempt to minimize the avoidable design changes. The majority of the corrective actions and/or preventive measures that might be implemented to minimize the design changes came from the result of the interviews with professionals that have been specifically conducted for this study and reported in section 6.1 of this chapter as well as from the identified causes of design changes in the previous sections of this work. Table 6.20 shows the required corrective actions and/or preventive measures along with their mean scores and ranks as perceived by the participated groups.
As it can be seen from Table 6.20, clients, consultants and contractors have considered “allocating sufficient time at the initial design stage to implement properly clients’ idea and to finalize the requirements of the proposed work” is the most important factor that needs to be well thought-out to avoid expensive design changes. They have “strongly agreed” in the highest rank of this factor with a weighted average score of 4.629. In many cases, clients do not see their basic requirements being implemented until the late design stage or event at the construction. This is in most cases due to lack of briefing clients in regular basis on the progress of the design work and discussing with them any technical problems or alternative opinions that might deviates clients’ requirements. Many clients also do not get involve much at the design stage because they are too busy or short of technical experience and expect their ideas to be implemented with a minimum time and discussion with them. In addition, there are cases where construction works start before the completion of design. For such cases, consultants come under pressure to produce working drawings to contractors in a quicker manner to avoid delaying progress at sites. Most importantly, Consulting Engineers should understand in detail clients’ requirements and be able to implement them correctly. If consultants come in doubt, they should clear such doubt promptly.

145
Table 6.20 : Main Scores ( MS ) and Ranks ( R ) for Corrective Actions and/or
Preventive Measures to Minimize the Avoidable Design Changes
Corrective Action(s) and/or
Preventive Measure(s)
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R a) Allocating sufficient time at the initial design stage to implement properly clients' ideas and to finalize the requirements of the proposed work
4.636 1 4.444 1 4.857 1 4.629
1 b) Allocating sufficient time and funds at initial planning stage for feasibility studies, site investigations, detailing the existing site conditions and highlighting any site restrictions to avoid unexpected circumstances
4.545 2 4.431 2 4.429 3 4.477
2 c) Involving specialized professionals at early planning stage for any extraordinary and/or unfamiliar works that may require special design arrangement
4.091 7 3.889 6 4.571 2 4.148
5 d) Briefing and discussing with clients or their representatives in regular intervals the progress of the work and highlight any potential difficulties/concerns as early as possible
4.364 4 3.772 9 4.134 7 4.107 6 e) Advising clients at early stages of any potential impacts that may result from each proposed change in particular on fee and time aiming to minimize the changes
4.273 6 3.918 5 4.418 4 4.192 4

146
Table 6.20 : Main Scores ( MS ) and Ranks ( R ) for Corrective Actions and/or
Preventive Measures to Minimize the Avoidable Design changes (Continue)
Corrective Action(s) and/or
Preventive Measure(s)
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R f) Engaging an experience co-ordinator/project director to represent client would ease the design process and transmission of information to the design members but may influence fee if not taken into consideration
3.941 8 3.667 10 3.857 9 3.828
9 g) Setting up at the initial design stage a proper method of co-ordination and to be reviewed in regular basis to make any adjustment if deemed necessary
4.351 5 3.778 8 4.143 6 4.106
7 h) A simple communication channel and better method for transmission of information would improve the efficiency of coordination and approval process
3.818 10 3.864 7 3.827 10 3.836
8 i) A proper personnel evaluation and assigned responsibilities accordingly would assist assigning the right responsibility to the right personnel
3.545 12 3.556 12 3.571 12 3.555 12 j) Providing clear and comprehensive design brief at early stage
4.500 3 4.222 3 4.200 5 4.330
3

147
Table 6.20 : Main Scores ( MS ) and Ranks ( R ) for Corrective Actions and/or
Preventive Measures to Minimize the Avoidable Design Changes (Continue)
Corrective Action(s) and/or
Preventive Measure(s)
Clients Consultants Contractors
Weighted
Average
MS R MS R MS R MS R k) For each project, more effort is required to review the clauses of contract documents with reference to drawings in order to eliminate/reduce the inconsistency and deficiency between the documents
3.900 9 4.000 4 3.286 13 l) An improvement to the working atmosphere and job satisfaction would increase the spirits and motivation of people and hence to the quality of the work produced
3.200 13 3.642 11 3.726 11 3.484 13 m) Centralizing responsibility for overseeing proper coordination between clients and design members and contractors
3.600 11 3.222 13 4.000 8 3.578 11
Furthermore, clients should appoint consulting engineers who are capable for carry out their works with sufficient experience in the field. Unqualified consultants may not be able to meet clients’ ideas or end up with limited design criteria which might not be in line with clients’ requirements.
“Allocating sufficient time and funds at initial planning stage for feasibility studies, site investigations, detailing existing site conditions and highlighting any site restrictions to avoid un-expected circumstances” was scored the second highest by both clients “strongly agreed in the rank” and consultants “mostly agreed in the rank” with a mean scores of 4.545 and 4.431 respectively. Contractors have “mostly agreed” to give this factor third highest rank with mean score of 4.429.

148
Feasibility studies and site investigations/details are very important since they normally define the basic requirements of works that need to be developed further and they provide alternative options along with highlights in any technical problems and/or restrictions to the works with solutions to such cases at the initial stage of projects. Feasibility studies provide also an approximation to cost of work so that clients get aware of the required fund. Site investigations, on other hand, may reveal critical design parameters such as type and detail of under laying soil stratus. The successive detail design is usually based on the optimum options/solutions of the feasibility studies and site investigations. In many cases, major decisions and detailed design start before getting the result of feasibility studies and/or site investigations in an attempt to save time. Furthermore, clients sometimes feel that the return benefit of feasibility studies and site investigations do not justify the cost of such requirements. They prefer to by the risk of un-expected circumstances by saving money on these items which in turn increase the chances for design change at late stages.
It is also worth to mention that “providing clear and comprehensive design brief at early stage” was given the third rank by the participated groups to minimize the design changes with a weighted average of 4.330. Design changes might take place due to unclear design briefs and in many instances this lead to disputes in what is included and what is not in the original design scopes. For large scale projects, there are normally more detailed design briefs on the major elements of works and less concentration on the secondary parts. It is also common in the construction industry to leave the small items without design brief in which consultants later on may claim extra money for designing these elements. So, it is essential to define precisely the scope of work and to give comprehensive detail of the required services at design tender stage to reduce the chances of modifying the original design scopes.
Table 6.21 below shows the result of the statistical test that has been conducted on this group of corrective actions and/or preventive measures to minimize the design changes. The Spearman’s correlation coefficients ratios, rs, and t-statistics indicate a significant agreement in the rankings hence the null hypothesis
H
0
is rejected for the three groups. The alternative hypothesis H
1
: that there is a

149 significant agreement in the ranking between the three groups with 95% confidence level was achieved.
Table 6.21 : Test for Agreement on the Ranking for Corrective Actions and/or
Preventive Measures to Minimize the Avoidable Design Changes
Group
Spearman’s coeff. rho.(r s
) t-statistics
(Calculated) t-statistics
(From ttable)
Reject
H
0
Clients and Consultants 0.775 4.067 Yes
Clients and Contractors
Consultants and Contractors
0.797
0.599
4..377
2.481
2.201 Yes
Yes
6.4.7 Preferences of Using the Existing Methods for Assessing the Fee of Design
Change
The methods of charging for consulting engineering services that have been identified from literature review of this study (refer to chapter two) are the Lump-
Sum Method, Salary Cost Times Multiplier Plus Non-Salary Cost Method, Cost Plus fixed Amount Method, Per diem Method, Percentage of Construction Cost Method and Retainer Method. The existing methods that have been used in the construction industry to assess the fee of design changes as exposed from the literature and the interviews with professionals (section 5.1 of this study) are the Man-Hour Method,
Percentage of Construction Cost Method, Area Unit Rate Method and Lump-Sum
Method. The objective of this section is to obtain professional opinions from the construction industry to determine the preference order of using each of the existing methods for assessing the fee of design change. Contractors have participated in this part of the questionnaire but later on their participation was found not appropriate since their involvement in assessing the fee of design change is minimal, if any.
Hence, contractors’ responses have not been included in the analysis of this section.
Table 6.22 below shows the common methods of assessing the fee of design changing along with their mean scores, MS and ranks, R as perceived by clients and

150 consultants. Both groups have agreed in the preferences order of the methods and have given the first preference to the “Man-Hour Method” followed by the “Lump-
Sum Method”, then the “Area Unit Rate Method” and last preference to use is the
“Percentage of Construction Method”.
Since both clients and consultants have agreed in the order of preferences to use the existing methods to assess the fee of design changes, refer to Table 6.22 below, the Spearman’s coeff. rho.(r s
) equals to +1.0 which indicates perfect correlation in the responses at 95% level of confidence.
Table 6.22 : Main Scores ( MS ) and Ranks ( R ) for Preference of Existing Methods for Assessing the Fee of Design Changes
Method
Clients Consultants
Weighted
Average
MS R MS R MS R
a) Man-Hours Method 2.000 1 1.333
1 1.700 1
b) Percentage of Construction
Cost Method
c) Area Unit Rate Method
3.000 4 3.444
4 3.200 4
2.909 3 3.111
3 3.000 3
d) Lump Sum Method 2.091 2 2.111
2 2.100 2
6.4.8 Limitations of the Existing Methods
The aim of this section is to identify the level of significance for each limitation in the opinions of clients and consultants for the most common methods of charging for design changes namely Man-Hour Method, Percentage of Construction
Cost Method, Area Unit Rate Method and Lump-Sum Method. Though, some of participated contractors in the questionnaire have responded to this part, their replies have been excluded in this section since their involvement in design fee changes issues is very limited. Six possible limitations have been identified and their rankings have been established in the next sections with highest mean score assigned
1 st
rank and the lowest one assigned 6 th
rank.

151
6.4.8.1 Limitations of the Man-Hours Method
Table 6.23 below shows the factors that have been considered by professionals as limitations of the Man-Hour Method. Clients’ and consultants’ mean scores for each possible factor are shown in this table as well along with their rankings. Clients have considered the main disadvantage of the Man-Hour Method is being “based on judgements, opinions and trust”. Hence, clients have given this factor the highest score of 3.250 in which they have “agreed in average” on the important level of significance to this factor while consultants have put this factor on the third rank with a mean score of 2.375. Clients have “slightly agreed” to consider this as a main disadvantage.
Table 6.23 : Main Scores ( MS ) and Ranks ( R ) for Limitation(s) of the
Man-Hours Method
Limitation(s)
Clients Consultants
Weighted
Average
MS R MS R MS R a) Not very accurate, not practical and not efficient
1.875 5 1.111
6 1.531 6 b) Not easy to justify the amount of design changes
1.750 6 1.444
5 1.612 5 c) Not easy to evaluate the fee of design changes d) Based on judgements, opinions and trusts
2.000 4 1.556 4 1.800 4
3.250 1 2.375 3 2.856 2 e) Produce high fee of design change compared to the original fee
3.150 2 2.625 1 2.914 1 f) The implementations may lead to disputes on the claims
2.250 3 2.500 2 2.362 3
Consultants, on the other hand, feel that the most important limitation of this method is being “producing high fee of design changes compared to the original fee”.
They have “agreed in average” to give this factor the highest rank through a mean score of 2.625. At the same time, clients have “agreed in average” as well to give even higher mean score of 3.150 to this factor yet in the second highest rank.

152
Combining the opinions of clients and consultants, this factor is considered to be the main disadvantage of the Man-Hour Method which limits its use as an efficient method to assess the fee of design change.
The “Man-Hour Method” is a widely used method in the construction industry to assess the fee of design changes, refer to the results of the interviews, section 6.2. Normally, consultants keep record of the actual hours used to alter the design and later submit them to their clients for payment. There are cases where consultants do not record the actual hours where this may increase the working load on the stuff to manage the timing. In such cases, consultants may submit to their clients an approximated time for the revised design Client do not always accept the claimed hours since they feel the fee is high compared to the original design fee and as a result negotiate the fee which may turn into disputes.
The results in Table 6.23 have been tested for correlation and significance level of agreement. The statistical analysis has yielded the following results:
Spearman’s coeff. rho.(r s t-statistics (Calculated) +2.421
t-statistics (From t-table) +2.776
The result of the above statistical tests indicates very good correlation in the ranking between clients and consultants since Spearman’s coeff. rho.(r s
) is +0.771 which is more toward the unity. The null hypothesis, H
0
, is rejected and the alternative hypothesis, H
1
is accepted. Hence, there is a significant level of agreement between clients and consultants on the ranking of limitations of the Man-Hour method at 95% level of confidence.

153
6.4.8.2 Limitations of the Percentage of Construction Method
Mean scores and rankings for each limitation of the Percentage of
Construction Cost Method as perceived by clients and consultants are shown in
Table 6.24. It is clear from this table that there is reasonable level of agreement in the rankings. Clients and consultants have given the highest rank due to their opinion on the main disadvantage of using this method as being “not easy to evaluate the fee of design changes”. In addition, Consultants have given second highest rank to the fact that the use of the method is “not easy to justify the amount of design change” while contractors have put this factor in the third rank with mean scores of
3.325 and 2.825 respectively. Unlike the Man-Hour Method, refer to last section, the
Percentage of Construction Cost Method has found not to “produce high fee of design change compared to the original fee” since both groups ranked this factor at lowest.
Table 6.24 : Main Scores ( MS ) and Ranks ( R ) for Limitation(s) of the
Percentage of Construction Cost Method
Limitation(s)
Clients Consultants
Weighted
Average
MS R MS R MS R a) Not very accurate, not practical and not efficient
2.625 5 3.000
4 2.794 5 b) Not easy to justify the amount of design changes c) Not easy to evaluate the fee of design changes d) Based on judgements, opinions and trusts
2.825 3 3.325
2 3.016 2
3.500 1 3.375 1 3.444 1
3.250 2 2.286 5 2.816 4 e) Produce high fee of design change compared to the original fee f) The implementations may lead to disputes on the claims
2.500 6 2.111 6 2.325 6
2.750 4 3.222 3 2.962 3

154
Traditionally, the Percentage of Construction Cost Method have been used for projects that have repetitive occurrence in which both clients and consultants have gained some familiarity from previous projects with the level of required services and design detail. The method was widely used in the past by consulting engineers where over the time the consultants have established some approximate correlations between the construction cost and the design fee. Since this method mainly depends on the past experience of both clients and consultants to correlate the construction cost with the design fee, it was reported (see section 3.10.5) that the cost of construction material so varied to the point where it comes almost not practical to be used as a guide for determining the consulting engineering fees.
A statistical analysis was conducted for the result in Table 6.24 to obtain the level of correlation and level of significance agreement on the responses to the limitations of the Construction Cost Method. The result obtained is as follow:
Spearman’s coeff. rho.(r s t-statistics (Calculated) +1.743
t-statistics (From t-table) +2.776
From above result the Spearman’s coeff. rho.(r s
) of +0.657 indicates good correlation in the obtained rankings. The null hypothesis, H
0
, is accepted and this proves that there is no significant agreement in ranking between clients and consultants at 95% level of confidence. Although the clients and the consultants both agreed in the limitations of the percentage of the construction cost method, they have shown different view on the significant level of each limitation.
6.4.8.3 Limitations of the Area Unit Rate Method
Table 6.25 shows the possible limitations of the Area Unit Rate Method in addition to mean scores and rankings of each limitation as viewed by clients and consultants. According to the result in Table 6.25, the highest mean score is obtained

155 for the factor that the use of the method is “not easy to justify the amount of design changes”. This highest score of 3.750 is attained from consultants group.
Consequently, consultants have placed this factor in the highest rank wherein clients ranked this factor second highest with mean score of 3.125. Merging the mean scores of the two groups for this factor yields a highest weighted average score of
3.406 which put this factor in overall first rank as a main disadvantage for the Area
Unit Rate Method.
Table 6.25 : Main Scores ( MS ) and Ranks ( R ) for Limitation(s) of the
Area Unit Rate Method
Limitation(s)
Clients Consultants
Weighted
Average
MS R MS R MS R a) Not very accurate, not practical and not efficient
3.000 3 3.556
2 3.250 2 b) Not easy to justify the amount of design changes c) Not easy to evaluate the fee of design changes
3.125 2 3.750 1 3.406 1
3.250 1 3.250 3 3.227 3 d) Based on judgements, opinions and trusts e) Produce high fee of design change compared to the original fee
2.750 5 2.286 5 2.541 5
2.875 4 2.000 6 2.481 6 f) The implementations may lead to disputes on the claims
2.500 6 3.111 4 2.775 4
In the opinion of clients, the main disadvantage of using this method is being
“not easy to evaluate the fee of design changes”. So that, clients have “agreed in average” to give this factor the highest rank with a mean score of 3.250. This factor was ranked in third place by consultants with mean score of 3.250 as well.
Referring to the result of the interviews section of this work, the use of the
Area Unit Rate Method is limited as a tool to assess the fee of design changes.
Nevertheless, knowing the area of any proposed project is very helpful and essential

156 since this gives an indication to size of projects and extend of the works require so that better assessment can be made to its design fees. The method has been used widely by small scale consultants to assess the design fees for one to three story buildings.
The result in Table 6.25 has been tested for correlation and significant level of agreement. The statistical analysis revealed the following parameters:
Spearman’s coeff. rho.(r s t-statistics (Calculated) +1.500
t-statistics (From t-table) +2.776
Hence, the null hypothesis, H
0,
for the above limitations have been accepted in which it confirms that clients and consultants do not agree significantly in their responses to the limitations of the Area Unit Rate method. This means that the clients have different view from the consultants on the use of the Area Unit rate for fee assessment of the design changes.
The principle of the Area Unite Rate Method is simple. To assess the design fee by this method, the floors areas of a building is multiplied by agreed area unit rate fee. In spite of its simplicity to assess the original design fee, it is not always practical to use the method for assessing the fee of design changes. As an example, for multi-story structures of identical floors with large spans areas, modifying one of the super structural elements, say shifting an interior column from its original place, will no doubt affect the surrounding areas which in this example are large areas. The required calculations to check the original design of each structural element to each floor is simple since the floors are identical. If the extra design fee is assessed by the effected areas of all floors, the fee comes very high.

157
6.4.8.4 Limitations of the Lump-Sum Method
Mean scores and rankings for each limitation of the Lump-Sum Method are shown in Table 6.26 as sighted by clients and consultants. The result in this table shows that consultants have “agreed in average” to give the highest rank to the factor in which the use of the method is “not easy to evaluate the fee of design changes”.
Clients have ranked this factor second highest. Combining both scores of consultants and clients produced a highest weighted average score of 2.969 which placed this factor in the highest rank.
Table 6.26 : Main Scores ( MS ) and Ranks ( R ) for Limitation(s) of the
Lump-Sum Method
Limitation(s)
Clients Consultants
Weighted
Average
MS R MS R MS R a) Not very accurate, not practical and not efficient
3.000 4 2.500
2 2.775 3 b) Not easy to justify the amount of design changes c) Not easy to evaluate the fee of design changes
3.125 3 2.250
4 2.731 4
3.250 2 2.625 1 2.969 1 d) Based on judgements, opinions and trusts
3.500 1 2.286 3 2.954 2 e) Produce high fee of design change compared to the original fee
2.625 5 2.125 6 2.400 5 f) The implementations may lead to disputes on the claims
2.500 6 2.187 5 2.359 6
In the opinion of clients, the method is “based on judgements, opinions and trust”. As a result, clients have believed in this factor as a main disadvantage so that they have given it the highest rank with mean score of 3.500. Consultants, on the other hand, have ranked this factor in the third place yet the second rank in the group of limitations went to this factor.
The result of the statistical test to the responses of participated clients and consultants indicated the following parameters:

158
Spearman’s coeff. rho.(r s
) t-statistics (Calculated) +1.743
t-statistics (From t-table) +2.776
From the above statistical test result, the null hypothesis, H
0
is accepted.
Hence, at 95% level of confidence, clients and consultants do not agree significantly in the ranking for the limitations of the Lump-Sum method.
The Lump-Sum Method, also known as a fixed price method, has been used widely by Consulting Engineers as a method of charging fees against the services they carry out. It is more applicable for new works rather than for design changes.
The main advantage of using this method for fee of design modifications is that upon reaching an agreement on the fee before modifying the design eliminates the chances of later disputes. However, it is not always possible to agree in advance on the fee of design changes especially at cases where it comes obvious that the fee of modifying the design is high compared to the original design fee. Furthermore, there are situations where it is not practical to negotiate and agree on the fee of each design change before executing the changes since this may hold the progress of the design.
Due to these facts, the use of the Lump-Sum Method is not free of limitations.
6.5 Chapter Summary
(1) The chapter presented the results of the interviews, the case studies and the questionnaire survey that have been conducted with the professionals working in the design and construction industry in the Sultanate of Oman. The aim for these investigation methods was to obtain initial opinions from the professionals on the extent of the problems associated with the design changes and to verify the need for investigating the proposed topic.
(2) The result of the interviews has shown many facts to substantiate the need for investigated problems under this research work. In addition, the sources, causes and

159 impacts of design changes have been verified by the respondents and the existing methods of assessing the fee of modifying the original structural design have been identified.
(3) Three case studies have been investigated in this chapter. These cases have provided actual examples on the size and effect of the design changes and have demonstrated the need for establishing a more practical method to assess the fee of the structural design changes.
(4) It has been shown in this chapter that the fee of the original design has been increased for case 1, case 2 and case 3 by 137.5%, 189.8% and 55.2% respectively due to the modifications in the original scopes. Similarly, the original construction completion times have been extended by 120.6% (case 1), 20.8% (case 2) and by
44.8% for case 3 as a result of the change.
(5) The chapter discussed the result of the questionnaire that was part of this investigation. The important level for the sources, causes and impacts of the design changes have been established along with the important level for the possible preventive measures to minimize the avoidable design change as perceived by the respondents to the questionnaire.
(6) The result of the questionnaire survey identified the limitations of the existing methods for assessing the fee of the structural design changes. It has been noticed that the existing methods are not accurate to use and not practical since the amount of the design changes can not be justified by these methods and hence not easy to evaluate the fee of the design changes. In addition, they are based on judgement and trust. Therefore, they may produce high fee of design changes compared to the original fee. As a result, their implementations may lead to disputes on the claims.
The limitations of the existing methods necessitated the need for more efficient method and gave a motivation for this research work.

CHAPTER 7
DEVELOPMENT OF THE PROPOSED POF METHOD TO ASSESS THE
FEE OF THE STRUCTURAL DESIGN CHANGES IN RC BUILDINGS
7.1 Introduction
This chapter highlights the details of the adopted structural design that have been intended to generate the data for developing a method for assessing the fee of the design changes. The chapter shows the percentages of time that has been estimated manually and by STAAD Pro software for designing structural group members of each type of buildings at preliminary and detailed design stages.
Graphical illustrations were provided to compare the results among the various buildings under the investigation. The findings of the statistical analysis in form of percentages of time which resulted from designing main structural members were furnished in a tabulated form and suggested to be the coefficients that might be used to assess the fee of the structural design changes. A mathematical expression that quantifies the percentages of design changes to that of original design was developed and related to the original design consultancy fee. This mathematical expression has been assigned a name “Percentage of Original Fee” (POF). The chapter also provides practical examples to demonstrate the use of the POF method. Finally, the POF method has been validated by a questionnaire survey in which the result is also presented in this chapter. The design of the buildings in this chapter has been divided into two phases namely preliminary structural design stage and detailed structural design phase.

161
7.2 Preliminary Structural Design Phase
Preliminary structural design consists of identifying all structural elements, their sizes and their locations without reinforcement details and normally determines by approximate methods and through the design experience. At this stage, the
Architect introduces the initial scheme of the project to other design members so that the most appropriate design system can be determined. As part of the design development, many ideas can be introduced at this stage and the co-ordination among the design members is essential for successful design. This might be needed for all participated design members to co-ordinate their design requirements and possibly to adjust their initial design schemes if deemed necessarily. In addition, it is common especially for fast track projects to prepare the Bill of Quantities, (BQ), based on the preliminary design and hence to tender the work in advance of the detailed design. Prior to the approval of the preliminary design, any design changes at this stage are usually not to be claimed for extra design fee.
The preliminary structural design for the buildings under this research work has been broken to eight main design activities. There are columns’ locations and sizing, plinth beams’ locations and sizing, floor beams’ locations, their load calculations and sizing, load calculation on slabs and sizing, load calculation on footings and sizing, stair case preliminary design, arches preliminary design and sections preliminary design. The following sections highlight the principle and the implemented methods of each preliminary design activity.
7.2.1 Locations of the Structural Members
The first thing in the structural design of concrete buildings is to determine the locations of the columns. They are generally governed by the architectural planning, the floor spans and the expected loads on the structural members. Many columns’ locations on buildings can be decided based on the architectural requirements such as architectural features, colonnades’ arches, spaces restraint and

162 so on. It is not an easy task to locate columns particularly for multi-story concrete buildings with dissimilar floor plans where the structural engineer should ensure proper columns’ locations to all floors such away that they do not stick out in unwanted areas. The direction of each column depends on the experience of the designer and the architectural plans as well. The subsequent locations and sizing of all structural members are directly interrelated to the columns’ locations. It is always recommended to locate the columns in the architectural plans of the buildings to avoid the problems of miss locations. At this stage, it is not possible to determine the size of the columns but nevertheless there sizes can be representative to their locations.
The locations of plinth beams are partially a factor of columns’ locations.
They are normally provided for two functions. The first one is to support the ground floor walls and the second one is to work as a restrain to the columns. Shorter wall length in order of less than 2 meters might not be located on plinth beams where it is sufficient to locate them directly on the concrete ground floors with or without slab thickenings.
Locations of floor beams, in the other hand, come next. They are to support roof slabs and floor walls on top of them and to transfer their loads to the columns.
Due to synthetic reasons, floor beams are located above the walls of lower floors so that they will not be seen from the top of lower floors unless fall ceiling is provided or architecturally is acceptable.
7.2.2 Load Calculations
Load calculations on roof slabs, floor beams columns and footings can be carried out after finalizing the locations of the structural members. Load on each roof slab is first calculated and it comes from their self weight, finishes and the likelihood live load. For the purpose of this study, and as required by the British standard BS8110 code of practice for concrete buildings, load calculation on slabs has been considered at the ultimate limit state only. Hence, a factor of 1.4 applied to

163 dead load and 1.6 applied to live loads. This load has been calculated to be uniformly distributed Kn/m 2 on slabs’ panels and hence used for slabs’ design.
Loads from roof slabs have been transferred to roof beams using shear forces coefficients of Table 3.15 in BS8110. This table is based on the yield line theory at the ultimate limit state. Self weight of the roof beams and walls’ weights on top, if any, were added to form the total weight per running meter on the beams at that floor. These loads were used for designing the floor beams at later stage.
Loads at each floor level have been transmitted to the columns by multiplying the load of individual beam by the span of that beam and divided by two so that the load of any given beam will be distributed to each supported member at the end of the beam. Where there are point loads, their loads were distributed to both end supports proportionally. Adding the column loads at each floor level with the self weight of that column will yield the total ultimate load on the footing for the column.
7.2.3 Sizing the Structural Members
With the availability of the loads on the structural members, their sizing can be determined either roughly by using approximate methods or exactly by using more detailed design methods. At preliminary design stage, it is common in the practice to approximate initially the sizes of the structural members so that other
Designers can check their design against the given structural members’ sizes and coordinate accordingly. Any architectural restrictions to members’ sizing can be observed at this stage.
The preliminary floor slabs thicknesses have been obtained using the basic span/effective depth ratio as stated in clause 3.4.6.3 of BS8110. Thus:
Minimum d =
( bs
Span
/ d
) x m
.
f
Equation 7.1
d ; the effective slab thickness

164
Span : is the shorter span bs/d : the basic span/effective depth ratio which can be obtained from
BS8110, Table 3.9. m.f
: modification factor ≤ 2
As example; for 5m X 7m simply support slab panel; the depth of the slab can be approximated as follow;
Span :
Shorter span = 5m bs/d
= 20 for simply supported; BS 8110, Table 3.9 m.f
: Can be assumed 1.5
Thus, d =
5000 mm
20 x
1 .
5
= 166.67 mm
By providing say 25 mm cover, and 12 mm diameter bars
Require slab thickness = h
= 166.67 mm + 25 mm + 12 mm/2 = 197.67 mm
A slab thickness of 200 mm can be initially selected.
The sizes of beams, either floor beams or plinth beams can be roughly obtained from the span and the approximate moment. For instance, the depth of 200 mm wide beams of span 4M might be 400 mm deep, 5m span might be 500mm, and for 6m span 600mm depth, etc. Moments can be found by
WL
2
8
for simply supported beams and approximated by
WL
2
10
for continuous spans, either at support or mid-span. Once the moment is obtained, the following expression can be used:
M bd
2 f cu
Limit this expression to 0.156; BS8110 Clause 3.4.4.4
If it is grater than 0.156 increase the beam’s depth
Columns’ sizes can be approximated from their ultimate vertical loads. As
For preliminary sizing, many consultants through their experience claimed that
200mm wide X 400mm deep short column can take ultimate axial load up to 600KN, for 200mm wide X 500mm deep short columns can take up to 800 KN ultimate axial

165 loads and for 200mm wide X 600mm deep short column can take up to 1000 KN and so on. Similarly, the 400mm wide X 400mm deep short column can take ultimate axial loads up to 1200KN, 400mm wide X 500mm deep short column can take up to
1600 KN and 400mm wide X 600mm deep short column can take up to 2000 KN.
For exact sizes, a more rigid analysis is needed and at the detailed design stage, these sizes shall be checked against all worst load cases through proper analysis and design process. An alternative method to the above is to use clause 3.8.4.3, equation 28 of
BS8110. For the preliminary design, one can assume that the columns are loaded axially and are not subjected to significant moments. In this case, the ultimate resistance,
N
, of a column section is:
N = 0.4f
cu
A c
+ 0.7A
sc f y
…………………..E
quation 28 of BS8110
In this expression, it is possible to calculate the ultimate moments’ capacities for different columns’ sizes with known concrete strength, f cu
,
, known steel yield strength, f y
, and assumed reinforcing steel, A s c
, say 1.0% of the area of the column size. As examples, for concrete grade 25, f c
= 25N/mm 2 and steel yield strength, f y
=
460N/mm 2 , 200mm X 400mm short column can take up to 1046KN ultimate axial load, for 200mm X 500mm short column the ultimate capacity is = 1308KN and for
200mm X 600mm short column, N =1570 KN. Once the ultimate moments’ capacities for different columns’ sizes are calculated, the values can be compared to the calculated columns’ ultimate axial loads and hence their sizes can be determined accordingly. In all cases, the resulting sections must be checked through appropriate design procedure to ensure proper amount of steel and all other design criteria have been met for worst loading conditions and for actual resulted forces, moments and stresses. For this study, all the designers have used the first described procedure to determine the preliminary sizes of the columns which later on have been checked through proper design procedure.
The sizes of the footings have been found from the calculated axial load at each column and by using normal design procedure. First of all, the columns’ loads were put in order started from the lowest column’s load and ended up with the maximum one. Secondly, a range of values have been allocated for each footing size. Finally, the size of each isolated footing is determined from the maximum load

166 in that range divided by the allowable soil capacity with an assumed footing depth.
For combined footings, normal design procedure have been followed but at this preliminary stage with out reinforcement detail.
7.2.4 Miscellaneous Structural Elements
Miscellaneous elements in this study include stair cases, arches and main sections that need structural design and detail. Normally all buildings, weather with one or more floors, have at least one stair, arches and need detailed sections.
Consequently they are considered main structural members that need to be addressed. Each building typically has number of arches in which many of them are identical in shape yet different in size. For the purpose of this study, three arches for each building under this research work have been allowed in the design to represent the most likely average arches types typically encountered in buildings and usually need detail. In addition, three sections have been considered in the design and the detail. The first one is being at the main entrance. The second one is for the detail of the parapet wall while the third one is through the windows
7.3 Detailed Structural Design Phase
Upon the approval of the preliminary design, it shall be progressed toward the detailed design in which the structural design is detailed for construction drawings.
At this stage, all structural calculations shall be performed to meet the design criteria and the proper detailing of the structural elements shall be provided. Final sizing of the structural elements and their detailed reinforcements shall be given along with all structural notes and specification. The result of preliminary design might be adjusted at this stage if necessary. Once the detailed design starts on any given part of the work, changes on the preliminary design of that part might be considered as a design variation if claimed by the consultant for extra fee.

167
The detailed design of roof slabs for the buildings of this research has been performed for at least three slabs’ panels for each floor using BS8110 provisions.
Ultimate moments are found first from the coefficients of Table 3.14 of the code.
Reference has been made to Sinha (2002) to check the shears and deflections to conform to the allowable limits on the code. Beams, on the other hand, were analyzed by moment distribution method with reference to Reynolds and Steedman
(1988) handbook and designed using the BS8110 code as well. For beams’ design, there were no limits to how many number of beams shall be designed for each floor.
Nevertheless, the structural design and analysis of each floor beams were carried out such the way that the outcome of the design is sufficient for construction purpose.
Columns have been designed using sub-frame analysis method. This method is simply distribute the unbalanced fixed-end moments resulting from a maximum load on a beam of longer span to one side of the column, and a minimum load on a beam of shorter span to the other side in proportion to the ratio of the column stiffness to that of the total stiffness of the members meeting at that support (Moseley et al.1999). All designed columns for the building under this research work turned out to be short columns with either uni-axial or biaxial moments. Practically, number of columns within a building can be identical in size and reinforcement. So, each building in this research has got three to six different types of columns according to their loads and the design was carried out for worst load case and arrangement of each type. Once there were reasonable numbers of different types of columns have been designed and hence their timing established, it was not necessary to repeat the lengthy calculations for designing the columns for all the buildings.
Instead, the established time has been taken as an average to estimate the required time for designing the columns of other buildings.
The design of footings for the buildings has been undertaken with reference to the procedure used by Ray (1995). Allowable bearings capacities for the soils were assumed to be between 150 Kn/m 2 to 200 Kn/m 2 . All footings have been regarded as to be shallow foundation. Piled and raft foundation were not considered in this study since they are not common in the Sultanate of Oman due to the nature of the soil in the region. Most footings turned out to be isolated ones with many

168 number are being combined footings. At this detailed design stage, footings have been checked for shear at the column face, one way shear at d from the column face and for two way shear at 1.5d from the column face.
7.4 Preliminary Structural Drafting Phase
Similar to the design of the buildings, drafting time has been recorded at two stages namely the time for preliminary drafting and the time for detailed drafting.
Each stage has its own timing record so that the total time for the preliminary design of a building is the sum of the preliminary designing time and the preliminary drafting time. This preliminary timing can be correlated proportionally percentage wise between the preliminary design and the detailed design and subsequently to the fee of designing the structure.
The structural detail of the buildings under investigation has been drafted by
AutoCAD software. The architectural plans of the building and their architectural detailed sections have been provided for structural design and drafting. These architectural drawings have been modified to match the requirements of the structural drafting details.
At the preliminary drafting phase, the locations of the structural members along with their sizes have been provided without reinforcements. The preliminary drafting has been generated with respect of the following:
• Plan for columns’ locations;
• Plan for footings’ locations;
• Plan for plinth beams’ locations;
• Plan for each roof slabs/beams; and
• Concrete profiles with dimensions for stairs, arches and sections

169
Appendix D shows an example on the level of the structural drafting for one of the buildings that have been adopted for this study
The preliminary sizes for the columns have been furnished in a form of columns’ sections while the sizes for the footings were specified in form of schedule.
The sizes of the plinth beams have been marked on the plinth beams plan itself whereas the thickness of roof slabs and the sizes of roof beams were presented on the plan of roof slabs/beams for each floor. Typical details of previous works have been used for next buildings whenever applicable such as columns cross sections, beams and footings’ schedules. Only modifications to their contents have been made. This approach no doubt quantifies the drafting time and hence no reason not to use the available details if they are relevant to other buildings.
For complete preliminary drafting of buildings, miscellaneous structural elements such as stairs, arches and cross-sections need to be provided as well. As it was mentioned previously, time has been established for one stair case, three arches and three cross sections for each of the buildings. The profiles of these elements were taken from the architectural details and were customized to match the requirement of the structural drafting details. At this stage, only the concrete profiles of these elements with dimensions have been given in the drawings. For the stair, two sections have been furnished. The first one is for the stair flight from ground floor to first landing while the second section is from the first landing to the roof of ground floor. For buildings of more than one floor, the stair cross sections between the floors are identical to the one of ground floor for that building. For the arches, the detail consists of an elevation and one cross-section taking at each arch apex for each building.

170
7.5 Detailed Structural Drafting Phase
Once the preliminary structural design has been checked and fulfilled the requirements of other disciplines, the detailed design shall commence next. At this detailed structural design stage, all structural members have been provided with full details to include final dimensions, detailed reinforcements, detailed sections and all structural notes and specifications that are appropriate to each building in this research study. The preliminary drafting has been modified accordingly to detailed design. Reinforcements detail were added to the preliminary columns’ details and reinforcements schedules for beams, slabs and footings are all part of this detailed phase. All details were in the level of the construction detail in all aspects. This activity completes the whole design and drafting of the structural design cycle in which buildings might then be progressed to the construction stage.
7.6 General Approach for Developing the Proposed POF Method
As mentioned previously, there are four types of buildings under this investigation ranging from one floor to four floors. Each group of building was defined to represent the number of floors. The general approach to develop the proposed POF method has been carried out in the following order:
• Establishment of percentages of time to analyse each main structural group members for preliminary structural design;
• Establishment of percentages of time to draft each main structural group members for preliminary structural drafting;
• Establishment of combined percentages of time to analyse and draft each main structural group members for preliminary structural design and drafting;
• Comparison between the estimated percentages of time to analyse main structural members for combined preliminary design and drafting;

171
• Establishment of percentages of time to design each main structural group members for detailed structural design;
• Establishment of percentages of time to design each main structural group members for detailed structural drafting;
• Establishment of percentages of time to design and draft each main structural group members for detailed structural design and drafting; and
• Comparison between the estimated percentages of time to design and draft main structural members for combined detailed design and drafting
The chronological order of listing the structural members has been established such the way that it follows the most commonly used order of designing in the practice. The listing of the members has been kept identical for both preliminary and detailed design stages so that it becomes easier to have like-to- like comparison and evaluation
To generate the data that is needed for the development of the POF method for assessing the fee of the structural design changes, two methods have been adopted. The first one is based on the manual calculations and the second method is based on STAAD Pro design software. By using the manual design method, the monitoring and distribution of the time among the structural members is more precise and hence gives better allocation for the timing compared to STAAD Pro design method. The reason behind this is being that the time requires for modeling the structure by STAAD Pro software is a common time for all members which cannot be distributed to the individual elements Therefore, it was found to develop the POF method for the structural design changes based on the manual method and use the STAAD Pro design software for comparison. Due to the above facts, all the buildings under this research have been designed manually and the one and two floors buildings have been designed by STAAD Pro design software.

172
7.7 Design by Manual Method
7.7.1 Preliminary Design and Drafting for One Floor Buildings
Time that has been recorded for designing main structural members at preliminary design stage for the three buildings of one floor each is shown in Table
7.1 below along with their corresponding percentages of time. As it can be seen from this table, there is no much variation on the percentages of time among the buildings for each structural group. The majority of the time has been spent on load calculations and sizing of footings followed by the time for floor beams’ locations, their load calculations and their sizing.
Table 7.1 : Time, in Minutes, and Percentage of Time for Preliminary Structural
Design (One Floor Buildings)
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations, loads’
calculations and sizing
4. Load calculations on slabs and
Sizing
5. Load calculations on footings
And sizing
6. Stair case preliminary design
7. Arches preliminary design
BUILDING REFERENCE
Time
1A
% of
Time
Time
1B
% of
Time
1C
Time
% of
Time
22 9.78 26 9.59 41 10.82
15 6.67 15 5.54 27 7.12
56 24.89
7 3.11 10 3.69 7 1.85
84 37.33
69 25.46 83 21.90
94 34.69 149 39.31
14 6.22 23
12 5.33 19
8.49
7.01
18
31
4.75
8.18 preliminary 15 6.67 15 5.54 23 6.07
Total 225 100 271 100 379 100

173
The intension of the preliminary design stage is to come up with complete preliminary design drawings that can be presented to clients. Therefore, the preliminary design has been drafted by AutoCAD software in which its timing and percentages of time for the structural members are listed in Table 7.2. It is obvious from this table that the total timing for drafting is more compared to the one for designing. Furthermore, the percentages of timing for locating and sizing the columns, stairs, arches and sections are close to each other but the highest percentages are being for footings’ locations and sizing while the lowest are being for the slabs’ locations and sizing.
Table 7.2: Time, in Minutes, and Percentage of Time for Preliminary Structural
Drafting (One Floor Buildings)
ACTIVITY
BUILDING REFERENCE
Time
1A
% of
Time
Time
1B
% of
Time
1C
Time
% of
Time
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations and
Sizing
4. Slabs' locations and sizing
6. Stair case preliminary
drafting
7. Arches preliminary drafting
21 7.07 17 4.79 39 9.61
17 5.72 28 7.89 18 4.43
8 2.69 7 1.97 12 2.96
51 17.17 62 17.46 49 12.07
57 19.19 40 11.27 68 16.75
Total 297 100 355 100 406 100
The percentages of the preliminary structural design members have been combined with the percentages of the preliminary structural drafting to form a complete set of preliminary structural design drawings. The result of these combined

174 percentages of time including the mean and the standard deviation for each of the structural members is shown in Table 7.3.
Table 7.3:
Percentage of Time for Preliminary Structural Design and Drafting (One
Floor Buildings)
ACTIVITY
1A
BUILDING
REFERENCE
1B 1C
% of
Time
% of
Time
% of
Time and 13.41 14.06 11.72 13.06 1.21
2. Plinth beams' locations and
Sizing
6.90 5.11 8.41 6.81 1.65
3. Floor beams’ locations and sizing 13.98 15.50 12.87 14.12 1.32 locations sizing 2.87 2.72 2.42 2.67 0.23 and 27.20 29.39 32.87 29.82 2.86
6. Stair case 12.45 13.58 8.54 11.52 2.65
13.22 9.42 12.61 11.75 2.04
9.96 10.22 10.57 10.25 0.31
Total 100 100 100 100
In the above table, the percentages of time for preliminary structural design and drafting have been calculated proportionally among the three buildings using the following relation:
% of Time for Des
.
&
Dra
.
an Activity
=
% of T for Act .
Des .
Total T for
X
Des
Total
.
&
T
Dra .
for Des .
+
% of T for Act .
Total T
Dra for
.
X
Des .
Total
&
T
Dra .
for Dra .

175
As an example, for building 1A, the % of time for preliminary design of columns’ locations and sizing is 9.78% and total design time is 225 minutes ( from
Table 7.1). The corresponding % of time for preliminary drafting is 16.16% and the total drafting time is 297 minutes (Table 7.2). The total time for the preliminary design and drafting building 1A is 225 + 297 = 522 minutes.
Thus: the percentage of time for preliminary design and drafting the columns for building 1A =
9 .
78
X
522
225
+
16 .
16
X
522
297
= 13 .
41 %
The mean for percentages of time for structural members has been calculated which is the average of the percentages for the three buildings. These calculated means for each activity have been considered to be the coefficient that might be used to quantify the amount of design changes as it will be seen in the forthcoming sections of this chapter. Standard deviations have also been included in the analysis to provide as a guide in which how the data is dispersed from the means and hence might be used to consider a range of percentages rather that the mean percentage for any given activity.
To get a comparison between the estimated percentages of time to design main structural members for the three buildings at the preliminary design stage,
Figure 7.1 shows such comparison. It is clear from this figure that the result at each structural member is almost consistent with maximum percentages are being for footings’ locations and sizing. This is due to the fact that to get the sizes of the footings which are necessary for preliminary design, it involves calculating the loads from top roof to footings level. This is where the most of time has been consumed specially the design has been carried out manually. This could be faster and hence the relation might be changed if the analysis of the buildings has been performed with assistant of computer software.
The locations and sizing of the floor beams came in the second highest percentages of time. The reliability of the design and its economic aspect no doubt are factor of floor beams’ locations and hence the flooring arrangements. Such arrangement needs to be well thought about not only to ease the design process but also the construction work at later stage. Slabs’ locations and sizing, on the other

176 hand, have taken the least time because they depend on the locations of the floor beams. Sizing the floors slabs needs simple calculation and in most cases they need only the experience of the designer to decide the sizes.
35%
30%
Bld. 1A
Bld. 1B
Bld. 1C
25%
20%
15%
10%
5%
0%
Arc hes
Col um
Fl. b ns' l oca eam s' lo t. &
siz
Foo ting ing cat. s' lo
& s
Plin th b
Sec eam s' lo tion s izin cat. g
& s izin g
Sla bs' l cat.
& s izin g
Sta irs oca t. &
siz ing
Structural Members
Figure 7.1 :
Percentages of time for the one floor buildings at preliminary design stage base on manual method
7.7.2 Detailed Design and Drafting for One Floor Buildings
The basic requirement of the detailed design is to go through all the analysis, design calculations and to confirm the design to the regulations of code of practice used. Table 7.4 shows the time that has been recorded for designing main structural members at detailed design stage for the three buildings of one floor each as well as their corresponding percentages of time. A close look to this table reveals that there are some variation in the results especially for the detailed design of columns, plinth

177 beams and floor beams. To design columns, it needs lengthy calculations and hence more time than for other structural members. If number of columns to be design in any given building is increased say only by one column, this is sufficient to increase the percentage of time to design all columns for such building by reasonable margin compared to other buildings in the investigation that are of one column less than in the other two. Floor beams and plinth beams can also have variations since their detailed structural design depend on the number of beams to be considered for the design at each floor level and the number of spans for such beams. Normally simply supported beams takes much less time to design compared to the continuous beams of unequal spans and with points loads. All these facts have contributed the variations on the above mentioned members but nevertheless the variations are not out of expected range. The detailed design of the slabs, footings, stairs, arches and the sections have relatively consistent results since the design of these members require simple calculations such the ones for the slabs, stairs and footings while for the arches and section there are almost no calculations required.
Table 7.4 :
Time, in Minutes, and Percentage of Time for Detailed Structural
Design (One Floor Buildings)
ACTIVITY
1. Columns' detailed design
2. Plinth beams' detailed design
3. Floor beams’ detailed design
4. Slabs' detailed design
5. Footings' detailed design
6. Stair case detailed design
7. Arches' detailed design
8. Sections' detailed design
1A
Time
% of
Time
Time
1B
% of
Time
1C
Time
% of
Time
255 48.94
255 36.69 340 53.63
57 10.94
70 10.07 44 6.94
98
47
32
11
14
7
BUILDING REFERENCE
18.81
9.02
6.14
2.11
2.69
1.34
212
53
60
16
20
9
30.50 104 16.40
7.63
8.63
2.30
2.88
1.29
54
53
14
12
13
8.52
8.36
2.21
1.89
2.05
Total 521 100 695 100 634 100

178
The time and its percentage for drafting the detailed design of the structural members for the one floor buildings are shown in Table 7.5 Unlike the preliminary design and drafting stages, the total timing for draft detail is less than the one for the design detail. Furthermore, the percentages of timing for columns’ detailed drafting is high for building 1C compared to the ones for buildings 1A and 1B. This is due to the fact that some columns for building 1C have irregular shapes which required more time to draw and hence to detail while the columns for the other two buildings have simple rectangular shapes. In addition, the drafting details for the stairs and the arches have taken the highest percentages because these members required having sections so that an additional time was spent to draw these sections. Slabs and footings have taken the least time since their detailing requires only scheduling.
Table 7.5 : Time, in Minutes, and Percentage of Time for Detailed Structural
Drafting (One Floor Buildings)
ACTIVITY
1. Columns' detailed drafting
2. Plinth beams' detailed
Drafting
3. Floor beams’ detailed
Drafting
4. Slabs' detailed drafting
5. Footings' detailed drafting
6. Stair case detailed drafting
7. Arches' detailed drafting
8. Sections' detailed drafting
1A
Time
5
% of
Time
Time
1B
% of
Time
1C
Time
% of
Time
2.45 10 4.10 42 16.28
33 16.18
46 18.85 26 10.08
34 16.67
46 18.85 32 12.40
8 3.92 5 2.05 11 4.26
5 2.45 5 2.05 7 2.71
38 18.63
49 20.08 55 21.32
57 27.94
57 23.36 46 17.83
24 11.76
26 10.66 39 15.12
Total 204 100 244 100 258 100
Similar to the preliminary design stage, the percentages of the detailed structural design members have been combined with the percentages of the detailed structural drafting to form a complete set of detailed structural design drawings. The

179 result of these combined percentages of time including the mean and the standard deviation for each of the structural members is shown in Table 7.6. The calculation for the combined percentages for the detailed design stage is similar to the one that has been shown for the preliminary design stage.
Table 7.6 : Percentage of Time for Detailed Structural Design and Drafting (One
Floor Buildings)
ACTIVITY
BUILDING
REFERENCE
1A
% of
Time
1B
% of
Time
1C
% of
Time
35.86 28.22 42.83 35.64 7.30
2. Plinth beams' details
3. Floor beams’ details
12.41 12.35 7.85 10.87 2.62
18.21 27.48 15.25 20.31 6.38
7.59 6.18 7.29 7.02 0.74
5.10 6.92 6.73 6.25 1.00
6.76 6.92 7.74 7.14 0.52
9.79 8.20 6.50 8.17 1.65
4.28 3.73 5.83 4.61 1.09
In the above table, the standard deviation turned out to be the highest for columns’ details with a value of 7.3. This value is considered high and hence their percentages of time are widely dispersed from the mean values. This is a reflection of the fact that columns take reasonable time to design compared to other members and more time as well to draft irregular columns’ shapes. As previously mentioned earlier, an increased number of columns to be designed and drafted for one of the buildings would lead to such variations in the result for other buildings.

180
The details of slabs, footings, stairs and the sections have taken the least time with low values of standard deviations. This is expected because a minimum works involve for designing and detailing these members compared to their preliminary design especially for the footings. Hence, with some modifications to the preliminary design, the detailed design can be obtained. The structural details of the slabs and footings, as an example, required to have scheduling to show their reinforcement details.
Figure 7.2 shows the comparison between the estimated percentages of time to design main structural members for the three buildings of one floor each at the detailed design stage. It is clear from this figure that the results for detailed design of columns, plinth beams and floor beams are not consistent with each other with maximum percentages are being for columns and floor beams. Furthermore, unlike the preliminary design of these buildings where the maximum percentages of time were recorded for footings’ locations and sizing, at the detailed design the maximum percentages were being for columns’ detailed design.

181
45%
40%
35%
30%
25%
20%
15%
10%
Bld. 1A
Bld. 1B
Bld. 1C
5%
0%
Arc hes'
Col det.
des um ign ns' d
Fl. b eam et. d esig n s' d et. d
Foo ting s' d et. d esig n
Plin th b esig n
Sec eam s' d tion s' d
Sla et. d esig n bs' d et. d esig et. d n
Sta irs' d esig n et. d esig n
Structural Members
Figure 7.2 : Percentages of time for the one floor buildings at detailed design stage base on manual method
7.7.3 Preliminary Design and Drafting for Two Floor Buildings
Table 7.7 shows the time that was needed for designing main structural members at preliminary design stage for the three buildings of two floors each as well as the corresponding percentages of time for these structural members. The result of the obtained data does not show much variation on the percentages of time for the structural group members among the buildings. Nevertheless, most of the recorded time at this stage for this group of buildings was spent for load calculations on footings and their sizing followed by the time for the floor beams’ locations, their load calculations and their sizing.

182
Table 7.7: Time, in Minutes, and Percentage of Time for Preliminary Structural
Design (Two Floors Buildings)
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations, loads’
calculations and sizing
4. Load calculations on slabs
And sizing
5. Load calculations on footings
And sizing
6. Stair case preliminary design
7. Arches preliminary design
BUILDING REFERENCE
Time
2A
% of
Time
Time
39 8.63 48
2B
% of
Time
8.56 29
2C
Time
% of
Time
9.18
13 2.88 16 2.85 19 6.01
121 26.77
12 2.65 20 3.57 13 4.11
217 48.01
192 34.22 96 30.38
208 37.08 115 36.39
14 3.10 27
17 3.76 29
4.81
5.17
15
18
4.75
5.70 preliminary 19 4.20 21 3.74 11 3.48
Total 452 100 561 100 316 100
To complete the stage of the preliminary structural design to the level of normal practice, the preliminary design was drafted and its recorded time with its equivalent percentages is presented in Table 7.8.

183
Table 7.8 : Time, in Minutes, and Percentage of Time for Preliminary Structural
Drafting (Two Floors Buildings)
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations and
Sizing
4. Slabs' locations and sizing
5. Footings' locations and sizing
BUILDING REFERENCE
Time
2A
% of
Time
Time
2B
% of
Time
2C
Time
% of
Time
75 14.76
46 11.36 75 15.43
40 7.87 39 9.63 50 10.29
80 15.75
52 12.84 87 17.90
10 1.97 8 1.98 13 2.67
85 16.73
90 22.22 70 14.40
6. Stair case preliminary drafting 66 12.99
60 14.81 66 13.58
7. Arches preliminary drafting 82 16.14
64 15.80 72 14.81
preliminary 46 11.36 53 10.91
Total 508 100 405 100 486 100
As is can be seen from this table and Table 7.7 above, the total time to draft the preliminary design is more for buildings 2A and 2C but less for building 2B. This is possibly due to the high percentage of time for building 2B to locate the floor beams, their load calculations and their sizing compared to other two buildings which is in turn resulted in lower total time for drafting. Furthermore, while columns, floor beams and footings have taken more percentages of time for their preliminary design in contrast with their drafting, the opposite can be observed for the plinth beams, stairs, arches and the sections in which they tend to have more time for drafting rather than for designing.
Normally there is no break down specification for the design and for the drafting. Thus, the preliminary design is a combination of design and drafting. In order to be in line with this, the total percentages of the preliminary structural design members have been combined with the percentages of the preliminary structural

184 drafting to form a complete set of preliminary structural design as shown in Table 7.9 along with calculation of the mean and the standard deviation for each of the structural members.
Table 7.9:
Percentage of Time for Preliminary Structural Design and Drafting (Two
Floors Buildings)
ACTIVITY
2A
BUILDING
REFERENCE
2B 2C
% of
Time
% of
Time
% of
Time
1. Columns' locations
And sizing
2. Plinth beams'
locations and sizing
3. Floor beams’
locations and sizing
4. Slabs' locations and
Sizing
5. Footings' locations
And sizing
6. Stair case
11.88 9.73 12.97 11.52 1.65
5.52 5.69 8.60 6.61 1.73
20.94 25.26 22.82 23.00 2.17
2.29 2.90 3.24 2.81 0.48
31.46 30.85 23.07 28.46 4.68
8.33 9.01 10.10 9.15 0.89
10.31 9.63 11.22 10.39 0.80
9.27 6.94 7.98 8.06 1.17
In the above table, the standard deviations came up to be reasonable with the majority of less than 2 except for footings’ locations and sizing where a value of 4.68 has been recorded. This result indicates that the individual percentage of time to design and draft each structural member in a given building is close to the mean value of the three buildings. This is due to the fact that buildings 2A, 2B and 2C are architecturally similar in nature and the degree of difficulty for their structural design is almost same. The above table also reveals that footings’ locations and sizing attained the maximum percentages of time among other members with a mean value of 28.46%. This result is similar to the one for one floor buildings in which the locations of footings and their sizing have scored the highest.

185
To get a comparison between the estimated percentages of time to design main structural members for the three buildings at the preliminary design stage,
Figure 7.3 shows such comparison. It is clear from this figure that the maximum variation in the result is for the footings’ locations and sizing. This much gap in the result could be contributed to the amount of calculation and steps involve to size the footings particularly their load calculation.
35%
30%
Bld. 2A
Bld. 2B
Bld. 2C
25%
20%
15%
10%
5%
0%
Arc hes
Col um
Fl. b ns' l oca eam s' lo t. &
siz
Foo ting ing cat. s' lo
& s
Plin th b cat. izin g
& s
Sec eam s' lo izin g tion s
Sla bs' l cat.
& s izin g
Sta irs oca t. &
siz ing
Structural Members
Figure 7.3 :
Percentages of time for the two floors buildings at preliminary design stage base on manual method
7.7.4 Detailed Design and Drafting for Two Floor Buildings
Table 7.10 shows the time that has been recorded for designing main structural members at detailed design stage for the three buildings of two floors each as well as their corresponding percentages of time. Referring to this table there are

186 some variation in the results especially for the detailed design of columns, floor beams and footings. These buildings have been designed structurally by three different designers. In general, the level of designing the structural components and hence the length of time for design calculations is directly related to the person who is performing the design. As an example, the design of floor beams can be achieved by one designer with, say, analysis of four different types of continues grids’ beams where for other designers possibly more beams need to be considered for the same floor. Nevertheless, the variation in the results closed up for the detailed design of the stairs, arches and the sections due to their minimum requirements of design calculations.
Table 7.10 : Time, in Minutes, and Percentage of Time for Detailed Structural
Design (Two Floors Buildings)
ACTIVITY
1. Columns' detailed design
2. Plinth beams' detailed design
3. Floor beams’ detailed design
4. Slabs' detailed design
5. Footings' detailed design
6. Stair case detailed design
7. Arches' detailed design
8. Sections' detailed design
BUILDING REFERENCE
Time
2A
% of
Time
Time
2B
% of
Time
2C
Time
% of
Time
340 43.87
420 38.50 209 34.60
54 6.97 90 8.25 82 13.58
125 16.13
311 28.51 138 22.85
113 14.58
153 14.02 53 8.77
99 12.77
66 6.05 90 14.90
18 2.32 14
16 2.06 19
10 1.29 18
1.28
1.74
1.65
14
10
8
2.32
1.66
1.32
Total 775 100 1091 100 604
The time and its percentage for drafting the detailed design of the structural members for the two floors buildings are shown in Table 7.11. Similar to the detailed design for one floor buildings, the total timing for draft detail is less than the one for the design detail. Furthermore, the variation in percentages of time for the

187 detailed drafting of these buildings is much less than the one for the detailed design.
This is due to the fact that the level of detailing and the amount of drafted information is almost identical for the three buildings. The percentage of time to draft the columns’ detail is higher for building 2B due to the number of irregular columns’ shapes that needed extra effort to draft. In addition, the drafting details for the stairs, the arches and the sections have taken higher percentages of time compared to their detailed design because these members required more detailing rather than designing.
Table 7.11 :
Time, in Minutes, and Percentage of Time for Detailed Structural
Drafting (Two Floors Buildings)
BUILDING REFERENCE
ACTIVITY
1. Columns' detailed drafting
Time
2A
% of
Time
25 9.19
Time
33
2. Plinth beams' detailed drafting 33 12.13
17
2B
% of
Time
13.58
7.00
Time
15
22
2C
% of
Time
7.21
10.58
3. Floor beams’ detailed drafting 48 17.65
44 18.11 36 17.31
4. Slabs' detailed drafting
5. Footings' detailed drafting
6. Stair case detailed drafting
7. Arches' detailed drafting
8. Sections' detailed drafting
8 2.94 7 2.88 8 3.85
7 2.57 9 3.70 9 4.33
43 15.81
39 16.05 47 22.60
58 21.32
53 21.81 44 21.15
50 18.38
41 16.87 27 12.98
Total 272 100 243 100 208 100
The percentages of the detailed structural design members have been combined with the percentages of the detailed structural drafting to constitute detailed structural design drawings. The result of these combined percentages of time including means and the standard deviations for each of the structural members is shown in Table 7.12. The values of the standard deviation in this table indicates that there is small degree of dispersions on the percentages of time from their mean

188 average for designing the structural members except the one for floors’ beams details which turned out to be dispersed widely from its mean since the standard deviation of these members is 5.04. This high standard deviation for floor beams’ detail is caused by the fact that a low percentage of time for floor beams’ detailed design has been recorded for building 2A (16.13%) compared to buildings 2B and 2C (28.51% and 22.85% respectively). It can also be seen from the table that the highest percentage of time belongs to columns’ details with a mean value of 32.14%. This is about one-third of the total detailed design and drafting time. The majority of this time was spent for detailed design calculations of the columns rather than for their detailed drafting.
Table 7.12 : Percentage of Time for Detailed Structural Design and Drafting (Two
Floors Buildings)
ACTIVITY
BUILDING
REFERENCE
2A
% of
Time
2B
% of
Time
2C
% of
Time
34.86 33.96 27.59 32.14 3.97
2. Plinth beams' details
3. Floor beams’ details
8.31 8.02 12.81 9.71 2.68
16.52 26.61 21.43 21.52 5.04
11.56 11.99 7.51 10.35 2.47
10.12 5.62 12.19 9.31 3.36
5.83 3.97 7.51 5.77 1.77
7.07 5.40 6.65 6.37 0.87
5.73 4.42 4.31 4.82 0.79
Figure 7.4 provides a closer-look comparison between the estimated percentages of time to design main structural members for the three buildings at the detailed design stage. The figure shows clearly the distribution of the time that was spent to design and detail the structural members. In addition, it is noticeable to see

189 how the values vary from each other particularly the ones for detailed design of columns, floor beams and footings. Similarly, the percentages of time for detailed design of the arches, slabs and stairs are consistent to each other and tend to be in the lower range in the distribution of the time between the members.
35%
30%
Bld. 2A
Bld. 2B
Bld. 2C
25%
20%
15%
10%
5%
0%
Arc hes' det.
Colu mn des ign
Fl. b s' d et. d eam s' d esig n
Foo ting et. d esig n
Plin s' d et. d th b eam esig n
Sec tion s' d et. d s' d
Slab s' d et. d esig n esig n et. d
Stai rs' d esig n et. d esig n
Structural Members
Figure 7.4 :
Percentages of time for the two floors buildings at detailed design stage base on manual method
7.7.5 Preliminary Design and Drafting for Three Floors Buildings
Time that has been recorded for designing main structural members at preliminary design stage for the three buildings of three floors each is shown in

190
Table 7.13 below along with their corresponding percentages of time. Although building 3C has taken the least total time to design (344 minutes) yet percentage wise to design its structural members still in line with buildings 3A and 3B that have higher total design time (630 Minutes and 768 minutes respectively). This is in fact the base for this part of the research where in general some designers are faster than others or some buildings are more complex to design but expecting the percentages to design the varies structural members for such cases are reasonably maintained.
Table 7.13 :
Time, in Minutes, and Percentage of Time for Preliminary Structural
Design (Three Floors Buildings)
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations, loads’
calculations and sizing
4. Load calculations on slabs and
Sizing
5. Load calculations on footings
And sizing
6. Stair case preliminary design
7. Arches preliminary design
BUILDING REFERENCE
Time
3A
% of
Time
Time
3B
% of
Time
3C
Time
% of
Time
51 8.10 84 10.94 39 11.34
34 5.40 24 3.13 19 5.52
212 33.65
247 32.16 63 18.31
13 2.06 12 1.56 11 3.20
264 41.90
320 41.67 165 47.97
20 3.17 29
24 3.81 33
3.78
4.30
16
20
4.65
5.81 preliminary 12 1.90 19 2.47 11 3.20
Total 630 100 768 100 344 100
It is obvious from the above table that there is reasonable consistency in the obtained data for this initial part of the design except building 3C where the floor beams’ locations, their loads’ calculations and their sizing have much less percentage of time (18.31%) in contrast with building 3A (33.65%) and building 3B (32.16%).
The majority of the time has been spent on load calculations and sizing of footings followed by the time for floor beams’ locations, their load calculations and their sizing.

191
The preliminary structural design of those three floors buildings has been drafted and their recorded drafting time along with their percentages is given in
Table 7.14. With comparison to the data in Table 7.13, Table 7.14 reveals that while buildings 3A and 3B have taken less time for drafting than for designing, this has revised for building 3C. Furthermore, the percentages of timing for locating and sizing the footings, columns, stairs and the arches were close to each other but the lowest percentages were recorded for slabs’ locations and their sizing.
Table 7.14 :
Time, in Minutes, and Percentage of Time for Preliminary Structural
Drafting (Three Floors Buildings)
BUILDING REFERENCE
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations and
Sizing
4. Slabs' locations and sizing
5. Footings' locations and sizing
Time
3A
% of
Time
Time
3B
% of
Time
3C
Time
% of
Time
85 17.00
59 12.04 75 13.71
45 9.00 42 8.57 50 9.14
93 18.60
12 2.40
100 20.41 110 20.11
8 1.63 11 2.01
65 13.00
97 19.80 78 14.26
6. Stair case preliminary drafting 70 14.00
64 13.06 69 12.61
7. Arches preliminary drafting 78 15.60
63 12.86 81 14.81
preliminary 57 11.63 73 13.35
Total 500 100 490 100 547 100
With a similar approach to the previous buildings, the total percentages of the preliminary structural design members have been combined with the percentages of the preliminary structural drafting for the three buildings so that a set of preliminary design was produced. Table 7.15 illustrates the obtained percentages when the design and the drafting were merged. Standard deviations and means for the structural members have also included for better assessment of the result.

192
Table 7.15
: Percentage of Time for Preliminary Structural Design and Drafting
(Three Floors Buildings)
ACTIVITY
3A
BUILDING
REFERENCE
3B 3C
% of
Time
% of
Time
% of
Time and 12.04 11.37 12.79 12.07 0.71
2. Plinth beams' locations and
Sizing
6.99 5.25 7.74 6.66 1.28
3. Floor beams’ locations and sizing 26.99 27.58 19.42 24.66 4.55 locations sizing 2.21 1.59 2.47 2.09 0.45
5. Footings' locations and sizing 29.12 33.15 27.27 29.85 3.00
7.96 7.39 9.54 8.30 1.11
7. Arches 9.03 7.63 11.34 9.33 1.87
5.66 6.04 9.43 7.04 2.07
Total
The values of the standard deviation in the above table indicate small degree of dispersions on the percentages of time from their mean average for designing the structural members. With theses standard deviations, a very good consistency in the result has been achieved. The highest was being for floor beams’ locations and sizing with a value of 4.55 followed by the one for footings’ locations and sizing
(3.00). The mean average for footings’ design and sizing turned out to be the highest with a value of 29.85%. This is due to the amount of the analysis of the three floors to get to the footing level for their sizing. In general, most of the time is required for sizing the footings compared to the time that is required for their detailed design.
While stairs, arches and sections have low percentages of time at the preliminary design stage, these percentages have increased for the combined design and drafting activities due mainly to increase in time for the preliminary drafting of these members.

193
Figure 7.5 shows the comparison between the estimated percentages of time to design main structural members for the three buildings of three floors each at the preliminary design stage. It is apparent from this figure the distribution of the percentages among various structural members and being the highest for footings’ location and sizing while the second highest is being for floor beams’ locations and their sizing. Locating and sizing the plinth beams, sections, slabs and the stairs came in the lower range of the distributed time for this group of buildings.
35%
30%
3A
3B
3C
25%
20%
15%
10%
5%
0%
Arc hes
Col um ns' l
Fl. b eam oca t. &
Foo s' lo
siz ing ting cat. s' lo
& s
Plin th b cat. izin g
& s
Sec eam s' lo izin g tion s
Sla bs' l cat.
& s izin g
Sta irs oac t. &
siz ing
Structural members
Figure 7.5 :
Comparison between the estimated percentages of time to design main structural members for the three buildings of three floors each at preliminary design stage

194
7.7.6 Detailed Design and Drafting for Three Floors Buildings
Table 7.16 gives you an idea about the time that has been noted down for designing main structural members at detailed design stage for the three buildings of three floors each in addition to their counterpart percentages of time. A close look to this table reveals that most of the time has been consumed for the columns’ detailed design and the floor beams’ detailed design came second in the order. These two main members have taken more than 50% of the total detailed design for each of the three buildings.
Table 7.16 :
Time, in Minutes, and Percentage of Time for Detailed Structural
Design (Three Floors Buildings)
ACTIVITY
1. Columns' detailed design
2. Plinth beams' detailed design
3. Floor beams’ detailed design
4. Slabs' detailed design
5. Footings' detailed design
6. Stair case detailed design
7. Arches' detailed design
8. Sections' detailed design
BUILDING REFERENCE
Time
3A
% of
Time
Time
3B
% of
Time
3C
Time
% of
Time
355 36.45
375 39.98 316 37.00
94 9.65 84 8.96 83 9.72
230 23.61
286 30.49 214 25.06
74 7.60 56
18 1.85 13
20 2.05 16
9 0.92 9
5.97
174 17.86
99 10.55 164 19.20
1.39
1.71
0.96
48
10
12
7
5.62
1.17
1.41
0.82
Total 974 100 938 100 854 100
Similar result to one floor and two floors buildings, detailed design of stairs, arches and the sections have taken low percentages of time compared to other structural members. The proportional time of designing these members is not effected by the increase number of floors for this group of buildings.

195
The time and its percentages for drafting the detailed design of the structural members for the three floors buildings are shown in Table 7.17. As it can be seen from this table, the total time for drafting detail is less than the one for designing detail. Furthermore, there is reasonable agreement in the estimated percentages of time for each group members in each building. In addition, the drafting details for the stairs, arches and the sections have fallen in the higher range of the percentages because these members required having sections so that an additional time was spent to draw these sections. Slabs and footings have taken the least time since their detailing requires only scheduling.
Table 7.17 : Time, in Minutes, and Percentage of Time for Detailed Structural
Drafting (Three Floors Buildings)
ACTIVITY
1. Columns' detailed drafting 17
BUILDING REFERENCE
Time
3A
% of
Time
7.33
Time
10
3B
% of
Time
3.58 12
3C
Time
% of
Time
4.67
2. Plinth beams' detailed drafting 21 9.05 35 12.54 26 10.12
3. Floor beams’ detailed drafting 52 22.41
42 15.05 49 19.07
4. Slabs' detailed drafting
5. Footings' detailed drafting
6. Stair case detailed drafting
7. Arches' detailed drafting
8. Sections' detailed drafting
7 3.02 9 3.23 11 4.28
11 4.74 12 4.30 12 4.67
44 18.97
51 18.28 55 21.40
46 19.83
66 23.66 54 21.01
34 14.66
54 19.35 38 14.79
Total 232 100 279 100 257 100
The data of Table 7.16 (detailed structural Design) has been combined statistically with the data of Table 7.17 (detailed structural drafting) to form one part detailed design section. The result of this combination is shown in Table 7.18. To assess the homogeneity of the data, the mean average and the standard deviations have been included in the table.

196
Table 7.18 : Percentage of Time for Detailed Structural Design and Drafting
(Three Floors Buildings)
ACTIVITY
3A
BUILDING
REFERENCE
3B 3C
% of
Time
% of
Time
% of
Time
30.85 31.64 29.52 30.67 1.07
3. Floor beams’ details
9.54 9.78 9.81 9.71 0.15
23.38 26.95 23.67 24.67 1.98
6.72 5.34 5.31 5.79 0.80
15.34 9.12 15.84 13.43 3.74
5.14 5.26 5.85 5.42 0.38
5.47 6.74 5.94 6.05 0.64
3.57 5.18 4.05 4.26 0.83
Total 100.00
100.00
100.00
100.00
It is clear from the above table that the obtained data is homogenous since the values of the standard deviations are low. This gives an indication in which the percentages of time to design the structural members at each building are being near to their mean values. Even though the footings’ details have the highest dispersion of time from their mean, their standard deviation of 3.74 considered low for detailing design of such elements. Furthermore, the majority of other standard deviations values came up to be less than one so that the result of this group of buildings turned up to be more consistent than the results of other previous buildings of one floor and two floors.
For better interpretation of the tabulated results for the three buildings of three floors each, Figure 7.6 illustrates the relations between the estimated percentages of time to design main structural members at the detailed design stage.
With a glance look to this figure, the uniformity of the attained percentages of time for the various structural members among the three buildings can be easily observed.

197
The figure also discloses the allocation of the percentages of time that have been taken to produce structural detailed design for those three buildings. To this end, footings’ and floor beams’ locations with their sizing came up on the peak of the curve for the three buildings. On the other hand, slabs’ locations and sizing came in the lowest range of the time for their design.
35%
30%
Bld. 3A
Bld. 3B
Bld. 3C
25%
20%
15%
10%
5%
0%
Arc hes'
Col det.
des um ign
Fl.b
ns' d et. d eam s' d esig n
Foo ting et. d esig s' d n
Plin th b et. d esig n
Sec eam s' d tion
Sla s' d et. d et. d esig n bs' d esig n et. d
Sta irs' d esig n et. d esig n
Structural Members
Figure 7.6 : Comparison between the estimated percentages of time to design main structural members for the three buildings of three floors each at detailed design stage
7.7.7 Preliminary Design and Drafting for Four Floors Buildings
Time that has been recorded for designing main structural members at preliminary design stage for the three buildings of four floors each is shown in Table
7.19 along with their corresponding percentages of time. Although the number of

198 floors for this group of buildings has increased to four floors, these buildings consist of either two to three bedrooms flats or flats with commercial shops at ground floors.
The architectural plan at each floor is almost identical to each other with small space areas for the rooms and for the facilities. Due to the above facts for these buildings, the structural arrangements of the floors were similar to each other. Hence, it was necessary to design only one floor for each building and used same design for other floors. This type of design is common for multi-story flats’ buildings or offices blocks.
Table 7.19:
Time, in Minutes, and Percentage of Time for Preliminary Structural
Design (Four Floor Buildings)
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations, loads’
calculations and sizing
4. Load calculations on slabs and
Sizing
5. Load calculations on footings
And sizing
6. Stair case preliminary design
7. Arches preliminary design
BUILDING REFERENCE
Time
4A
% of
Time
Time
4B
% of
Time
4C
Time
% of
Time
60 8.28 83 11.25 79 12.91
28 3.86 29 3.93 29 4.74
206 28.41
10 1.38 9 1.22 15 2.45
332 45.79
224 30.35 174 28.43
317 42.95 205 33.50
27 3.72 22
34 4.69 30
2.98
4.07
37
44
6.05
7.19 preliminary 28 3.86 24 3.25 29 4.74
Total 725 100 738 100 612 100
Referring to the above table, there is some variation in the percentages of time for load calculations on footings and their sizing. While buildings 4A and 4B have taken the highest percentage of time with values of 45.79% and 42.95% respectively, building 4C happened to have lower percentage of time with a value of
33.5% compared to other two buildings. Building 4C actually residential flats’ building of similar floors plans while buildings 4A and 4B are commercial buildings

199 having shops at ground floors and flats on top. So, the load calculations on the footings for building 4C was simpler compared to the ones for other two buildings.
The preliminary structural design of Table 7.19 has been drafted to produce a set of preliminary structural drawing and its recorded time with its equivalent percentages is presented in Table 7.20. At this preliminary design stage, the locations and sizing of the columns, plinth beams, stairs, aches and the section have taken more time for drafting than that for designing. On the other hand, the locations and sizing of floor beams and footings have undertaken less time for drafting. In general, preliminary design does not involve complete analysis of the structure.
Most of the preliminary design is based on approximate analysis. On the contrary, drafting at preliminary design stage is required to almost all main structural members.
Table 7.20 : Time, in Minutes, and Percentage of Time for Preliminary Structural
Drafting (Four Floor Buildings)
ACTIVITY
BUILDING REFERENCE
Time
4A
% of
Time
Time
4B
% of
Time
4C
Time
% of
Time
95 14.94
66 13.75 95 13.57
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations and
Sizing
4. Slabs' locations and sizing
50 7.86 45 9.38 75 10.71
154 24.21
11 1.73
106 22.08 201 28.71
8 1.67 14 2.00
5. Footings' locations and sizing 135 21.23
90 18.75 120 17.14
6. Stair case preliminary drafting 59 9.28 67 13.96 66 9.43
7. Arches preliminary drafting 70 11.01
59 12.29 68 9.71
Total 636 100 480 100 700 100

200
Table 7.21 illustrates the estimated percentages of time when the preliminary structural design and drafting of the three buildings were merged together. Standard deviations and means for the structural members have also been included in order to assess the consistency of the obtained result.
Table 7.21 : Percentage of Time for Preliminary Structural Design and Drafting
(Four Floors Buildings)
ACTIVITY
BUILDING
REFERENCE
4A
% of
Time
4B
% of
Time
4C
% of
Time
11.39 12.23 13.26 12.29 0.94
1. Columns' locations
And sizing
2. Plinth beams'
locations and sizing
3. Floor beams’
locations and sizing
4. Slabs' locations and
Sizing
5. Footings' locations
And sizing
5.73 6.08 7.93 6.58 1.18
26.45 27.09 28.58 27.38 1.09
1.54 1.40 2.21 1.72 0.43
34.31 33.42 24.77 30.83 5.27
6.32 7.31 7.85 7.16 0.78
7.64 7.31 8.54 7.83 0.64
6.61 5.17 6.86 6.21 0.91
In the above table, the values of the standard deviations indicate small degree of dispersions on the percentages of time from their mean average to design the main structural members at the preliminary design stage for this group of buildings. With theses standard deviations, a very good consistency in the result has been achieved.
Similar to the result of the previous buildings, the highest standard deviation is being for footings’ locations and sizing with a value of 5.27. This value is not consistent with other values of standard deviations. One possible reason to this is that there was different degree of difficulty to calculate the loads on footings and to size them between the three buildings and hence some variations on time were observed.

201
The percentages of time that have been presented in Table 7.21 are shown graphically in Figure 7.7 so that better comparison between the obtained results for the three buildings can be easily observed. The figure shows clearly the distribution of the time that was spent to design and detail the structural members with maximum percentages can be noticed in which they were recorded for footings’ location and sizing followed by floor beams. Arches, plinth beams, sections, slabs and stairs came in the lower part of this graph.
35%
30%
Bld. 4A
Bld. 4B
Bld. 4C
25%
20%
15%
10%
5%
0%
Arc hes
Colu mn
Fl.b
s' lo cat. eam s' lo
Foo ting
& s izin cat. g
& s s' lo
Plin th b izin cat. g
& s
Sec eam s' lo izin g tion s
Sla bs' l cat.&
siz ing
Sta irs oca t. &
siz ing
Structural members
Figure 7.7 :
Comparison between the estimated percentages of time to design main structural members for the three buildings of four floors each at preliminary design stage

202
7.7.8 Detailed Design and Drafting for Four Floors Buildings
The time and its percentages for detailing the preliminary design of the structural members for the four floors buildings are shown in Table 7.22. Examining this table gives an idea about the variations in the results that have taken place especially for the detailed design of columns between building 4A (36.8%) and building 4C (37.05%) compared to building 4B (47.95%). Large variation can be also observed for slabs’ detailed design for building 4A (11.26%) and buildings 4A and 4B (6.52% and 7.36% respectively). Columns’ detailed design involves lengthy calculations for their analysis and design. An increase number of columns to be designed for one of the buildings make reasonable variation in time of other buildings. The percentages of time to design slabs, on the other hand, are largely a function of number of slabs’ panels that need to be considered for design. In contrast, slabs’ design does not involve prolonged calculations and hence their percentages in the time distribution are low compared to other structural members such as floor beams and footings.
Table 7.22 :
Time, in Minutes, and Percentage of Time for Detailed Structural
Design (Four Floors Buildings)
ACTIVITY
1. Columns' detailed design
2. Plinth beams' detailed design
3. Floor beams’ detailed design
4. Slabs' detailed design
5. Footings' detailed design
6. Stair case detailed design
7. Arches' detailed design
8. Sections' detailed design
BUILDING REFERENCE
Time
4A
% of
Time
Time
4B
% of
Time
4C
Time
% of
Time
304 36.80
375 47.95 312 37.05
102 12.35
66 8.44 80 9.50
203 24.58
178 22.76 225 26.72
93 11.26
51
91 11.02
71
12 1.45 14
11 1.33 14
10 1.21 13
6.52
9.08
1.79
62 7.36
109 12.95
19 2.26
1.79 25 2.97
1.66 10 1.19
Total 826 100 782 100 842 100

203
The time and its percentage for drafting the detailed design of the structural members for the four floors buildings are shown in Table 7.23. It is clear from this table and Table 7.22 that more time was needed to go through the detailed design than that for detailed drafting. Furthermore, the variation in percentages of time for the detailed drafting of these buildings is much less than the one for the detailed design. This is due to the fact that the level of drafting information is almost identical for the three buildings.
Table 7.23 :
Time, in Minutes, and Percentage of Time for Detailed Structural
Drafting (Four Floors Buildings)
ACTIVITY
1. Columns' detailed drafting
UILDING REFERENCE
Time
4A
% of
Time
Time
17 6.03 10
4B
% of
Time
5.65 12
4C
Time
% of
Time
5.02
2. Plinth beams' detailed drafting 29 10.28
16 9.04 13 5.44
3. Floor beams’ detailed drafting
4. Slabs' detailed drafting
5. Footings' detailed drafting
6. Stair case detailed drafting
7. Arches' detailed drafting
8. Sections' detailed drafting
57 20.21
42 23.73 61 25.52
11 3.90 9 5.08 7 2.93
14 4.96 8 4.52 6 2.51
44 15.60
37 20.90 49 20.50
59 20.92
35 19.77 52 21.76
51 18.09
20 11.30 39 16.32
Total 282 100 177 100 239 100
The percentages of the detailed structural design members for the three buildings of four floors each have been combined with their counterpart percentages of the detailed structural drafting to set up detailed structural design drawings. The result of these merged percentages of time including means and the standard deviations for each of the structural members is shown in Table 7.24. The values of the standard deviation in this table indicate that there is a small degree of dispersions on the percentages of time from their mean average for designing the structural

204 members except the one for columns’ detail which turned out to be dispersed widely from its average mean since the standard deviation of these members is 6.18. This high standard deviation for columns’ detail is caused by the high percentage of time that has been obtained to design the columns for building 4B compared to other two buildings. This high percentage of time contributed to the more number of columns to be designed for building 4B compared to other two buildings. It can also be seen from the table that all other standard deviations are less than 2 which give indication of good uniformity of the obtained result.
Table 7.24 :
Percentage of Time for Detailed Structural Design and Drafting (Four
Floors Buildings)
ACTIVITY
4A
BUILDING
REFERENCE
4B 4C
% of
Time
% of
Time
% of
Time
28.97 40.15 29.97 33.03 6.18
2. Plinth beams' details
3. Floor beams’ details
11.82 8.55 8.60 9.66 1.87
23.47 22.94 26.46 24.29 1.90
9.39 6.26 6.38 7.34 1.77
9.48 8.24 10.64 9.45 1.20
5.05 5.32 6.29 5.55 0.65
6.32 5.11 7.12 6.18 1.01
5.51 3.44 4.53 4.49 1.03
To compare the results of the analysis for three buildings at the detailed design stage, Figure 7.8 shows such comparison in a graphical form. With a glance look to this graph, the portion of time that has been taken to detail various structural members can be easily seen. In addition, it is noticeable to see how the values vary from each other particularly the ones for detailed design of columns. With an exception to this structural member, the percentages of time to detail other structural

205 members were homogenous. Similar to the findings of the previous buildings, columns’ detailed design for this group of buildings happened to be on top of this time distributed curve followed by the floor beams’ detailed design.
45%
40%
35%
Bld. 4A
Bld. 4B
Bld. 4C
30%
25%
20%
15%
10%
5%
0%
Arc hes
Col
' de t. d um esig n ns' d
Fl. b eam et. d esig n s' d et.
Foo ting s' d et. des ign
Plin th b des ign
Sec eam s' d tion s' d
Sla et. d esig n bs' d et. des ign
Sta ir d et. d esig n et. d esig n
Structural Members
Figure 7.8 :
Comparison between the estimated percentages of time to design main structural members for the three buildings of four floors each at detailed design stage
7.7.9 Comparison of the Preliminary Design for the Four Types Buildings
To compare the results of all buildings under the investigation of this report,
Figure 7.9 illustrates the relations between the estimated percentages of time to design main structural members at the preliminary design stage. With a glance look at this figure, the values of the attained percentages of time for the various structural members among all four types of buildings can be easily compared. It can be seen

206 from the figure that there is a uniform relation in the distribution of the time among the buildings for their preliminary design. For example, footings’ locations and sizing have taken the highest percentages of the time for all buildings, followed by the floor beams’ locations and sizing. On the other hand, slabs’ locations and sizing have taken the lowest percentages of the time.
35%
30%
One Floor Bld.
Two Floors Bld.
Three Floors Bld.
Four Floors Bld.
25%
20%
15%
10%
5%
0%
Arc hes
Col um ns' l
Fl. b oca t. & eam s' lo
siz ing
Foo ting cat.&
siz ing
Plin th b s' lo cat.
& s izin g
Sec eam s' lo tion s
Sla cat.
& s izin g bs' l oca
Sta irs t. &
siz ing
Structural Memebrs
Figure 7.9 : Comparisons between percentages of time to design main structural members for the four buildings at preliminary design stage
7.7.10 Comparison of the Detailed Design for the Four Types Buildings
Similar comparison to the preliminary design stage has been made for the detailed design for the four types of the buildings under this investigation. The result of this comparison is shown graphically in Figure 7.10. This figure illustrates the

207 general tendency of the percentages of time for the structural design detail to all buildings. As it can be seen from this figure, there is not much variation in the percentages of time for the group members in each type of buildings. Furthermore, It is obvious from the figure that at the detailed design stage, the columns’ locations and sizing have received the highest percentages of time while the second highest went to the floor beams’ detailed design for all buildings. In contrast, the sections’ detailed design has taken the least percentages.
40%
35%
30%
25%
One Floor Bld.
Two Floors Bld.
Three Floors Bld.
Four Floors Bld.
20%
15%
10%
5%
0%
Arc hes
' de t. d
Col um esig n
Fl.b
ns' d et. d eam esig n s' d
Foo ting et. d esig n
Plin s' d et. d th b esig n
Sec eam s' d tion et. d s' d et. d esig n
Sla bs' d et. d
Sta esig n esig n irs' d et. d esig n
Structural Members
Figure 7.10 :
Comparisons between percentages of time to design main structural members for the four buildings at detailed design stage

208
7.7.11 Comparison between the Preliminary and the Detailed Design
Comparison was made to observe the approximate ratio of the preliminary design to that of the detailed design for the mean values of all buildings. Table 7.27 shows the estimated ratios of times between the two stages and Figure 7.11 gives a graphical comparison of the result. The obtained standard deviation for this comparison is 4.70 which indicates the level of dispersion of the result from their mean.
Table 7.25 :
Time, in Minutes, and Percentage of Time for Preliminary and Detailed
Structural Design and Drafting
Buildings
One floor buildings
Preliminary Design &
Drafting
Total Time
Percentage of Time
Detailed Design &
Drafting
Total Time
Percentage of Time
522 41.86 725 58.14
960 47.83 1047 52.17 Two floors buildings
Three floors buildings
Four floors buildings
% of Mean
Std. deviation
1130 48.37 1206 51.63
1361 55.12 1108 44.88
48.30 51.70
4.70 4.70

209
Preliminary Design
Detailed Design
60%
50%
40%
30%
20%
10%
0%
One floor building
Two floors buildings
Three floors buildings
Four floors buildings
Figure 7.11 :
Comparison between percentages of time for preliminary and detailed design stages
Referring to the above mentioned table and figure, the time for the preliminary design came less than that of the detailed design except for the four floors buildings. This is due to the fact that for the four floors buildings, the percentage of time required to carry out the preliminary design for the floor beams’ locations and sizing is much more compared to other three type buildings (refer to
Figure 7.9). Hence, this higher percentage of time is contributed to the geometric of the buildings and the degree of difficulty compared to other buildings. The following ratios can be suggested:
• One floor buildings, 40% preliminary design : 60% detailed design
• Two or three floors buildings, 48% preliminary design : 52% detailed design
• Four floors buildings, 55% preliminary design : 45% detailed design
A percentage of + or – 10 can be allowed for each value to cope for two standard deviation units. This allowance has been made in line with a well known

210 statistical relation between the standard deviation and the mean average in which for two standard deviations 95% of similar buildings are most likely will fall within the above ratios.
7.8 Design Based on STAAD Pro. Software
Structural Analysis And Design Professional, STAAD Pro., software has been used to carry out the design for the one and two floors buildings that have been designed manually and presented in the previous section. The reason behind this is to get a comparison between the likely percentages of time to design the structural members utilizing the advance development of the computer software for the structural design of RC buildings to the one by manual calculations.
To design concrete buildings by STAAD Pro software or by similar commercial structural software, it is necessary first to set up manually the general arrangements of the structure such as locating on plans the columns, beams, slabs and so on. Secondly, it requires to model the complete structure and to define the type of loadings to be considered for the design. The majority of the time normally requires for modeling the structure and if there are errors in the modeling it takes reasonable time to find the cause of such errors and to rectify them. Once the modeling is completed, the program calculates the required moments and forces for all members and if needed design them accordingly. It is common among the consulting engineers to use the structural design software for the analysis part and to carry out the design manually. This gives advantage to come up with more practical design and detailing over the software design. Unlike the manual calculations, the time requires for modeling a building is for the complete structure and hence cannot be allocated to each structural group members. It was necessary therefore to assume a certain distribution of the modeling time to the structural members so that percentages of time similar to the ones obtained by manual calculation can be achieved.

211
The analysis and the design of the above mentioned buildings have been carried out by the software except the design of the roof slabs, footings, arches, stairs and the sections in which it was found not practical to design such elements by the
STAAD Pro software and hence the time that was obtained by manual calculations has been used for this part. While the percentages of time have been established for the preliminary and detailed stages and presented in the forthcoming sections, the percentages of time for drafting the structural members as presented in the previous sections remain valid and hence have not been presented again for STAAD Pro method.
7.8.1 Preliminary Design and Drafting by STAAD Pro for One Floor Buildings
Time that has been recorded for designing main structural members at preliminary design stage for the three buildings of one floor each is shown in Table
7.26 below along with their corresponding percentages of time. As it can be seen from this table, there is not much variation on the percentages of time among the buildings for each structural group. The majority of the time has been spent on sizing the footings (similar to the findings of the manual method) followed by the time for columns’ locations and their sizing.

212
Table 7.26 : Time, in Minutes, and Percentage of Time for Preliminary Structural
Design Based on STAAD Pro Design Software (One Floor Buildings)
ACTIVITY
BUILDING REFERENCE
Time
1A
% of
Time
Time
1B
% of
Time
1C
Time
% of
Time
58 21.48
73 21.35 95 22.67
1. Columns' locations and sizing
2. Plinth beams' locations and
Sizing
3. Floor beams’ locations and
Sizing
4. Roof slabs’ locations and
Sizing
5. Footings’ locations and sizing
6. Stair case preliminary design
7. Arches preliminary design
51 18.89
60 22.22
62 18.13 81 19.33
71 20.76 81 19.33
7 2.59 10 2.92 7 1.67
53 19.63
69 20.18 83 19.81
14 5.19 23 6.73 18 4.30
12 4.44 19 5.56 31 7.40 preliminary 15 5.56 15 4.39 23 5.49
Total 270 100 342 100 419 100
The percentages of the preliminary structural design members have been combined with the percentages of the preliminary structural drafting (data of Table
7.2) to form a complete set of preliminary structural design drawings. The method of combining was discussed in detail in section 7.2. The result of these combined percentages of time including the mean and the standard deviation for each of the structural members is shown in Table 7.27.

213
Table 7.27 : Percentage of Time for Preliminary Structural Design and Drafting
Based on STAAD Pro Design Software (One Floor Buildings)
ACTIVITY
1A
BUILDING
REFERENCE
1B 1C
% of
Time
% of
Time
% of
Time and 18.69 19.37 17.70 18.59 0.84
2. Plinth beams' locations and
Sizing
12.70 11.34 14.55 12.86 1.61
3. Floor beams’ locations and sizing 13.58 14.20 12.61 13.72 1.03 locations sizing 2.64 2.44 1.70 2.00 0.30 and 19.58 22.81 23.27 21.89 2.01
6. Stair case 11.47 12.20 8.12 10.59 2.17
12.17 8.46 12.00 10.88 2.09
9.17 9.18 10.06 9.47 0.51
Total
100 100 100 100
To get a comparison between the estimated percentages of time to design main structural members for the three buildings at the preliminary design stage,
Figure 7.12 shows such comparison. It is clear from this figure that the result at each structural member is almost consistent with maximum percentages are being for footings’ locations and sizing while the minimum ones recorded for slabs' locations and sizing. This finding is in agreement with the one of manual calculations. As it can be also seen from this figure, there is no much variation among the three buildings in the obtained result. This is due possibly to the similarities of the buildings under the investigation.

214
25%
20%
15%
10%
5%
Bld. 1A
Bld. 1B
Bld. 1C
0%
Arc hes
Colu mn
Fl. b s' lo eam cat. s' lo
& s
Foo izin ting cat. g
Plin s' lo
& s th b cat. izin g eam
& s
Sec tion s' lo izin g s
Slab s' lo cat.
& s izin g
Stai rs cat.
& s izin g
Structural Members
Figure 7.12 : Percentages of Time for the one floor buildings at preliminary design stage based on STAAD Pro design Software
To compare the results between the manual design and the STAAD Pro
Design software for the three buildings of one floor each at preliminary design stage, the mean percentages of time are shown graphically in Figure 7.13. It is clear from the figure that the manual design has taken more time for footings' location and sizing compared to the one by STAAD Pro design software. This is due to the fact that to size the footings, the load shall be calculated to all structural members at each column location and hence to the footings in which manually required lengthy calculations. On comparison, STAAD Pro software has taken more time for columns and plinth beams locations and sizing compared to the manual design. The reason behind this is being that STAAD Pro takes more time for modelling the structure which in this case defining the nodes for the columns and defining the

215 elements for the beams. It can be also noted from Figure 7.13 that there are reasonable variations in the results of these members and the maximum variation was obtained for footings' location and sizing. On the other hand, The Arches, sections, slabs and the stairs have taken almost similar mean percentages of time. This was expected to some extend since these members have been design manually.
30%
By Manual Design
By Staad Pro Software
25%
20%
15%
10%
5%
0%
Colu mn
Plin s' lo cat. th b eam
Fl. b
& s izin s' lo g eam s' lo cat.
Slab s' lo
& s cat. izin
& s g
Foo cat. izin
& s g ting s' lo
Stai izin g rs
Arc cat.
& s izng hes
Structural Members
Sec tion s
Figure 7.13:
Comparison between manual design Vs. STAAD Pro design software for one floor buildings at preliminary design stage

216
7.8.2 Detailed Design and Drafting by STAAD Pro for One Floor Buildings
Table 7.28 shows the time that has been recorded for designing main structural members at detailed design stage for the three buildings of one floor each as well as their corresponding percentages of time. A close look to this table reveals that there are some variation in the results related to the detailed design of columns, footings and the plinth beams. Furthermore, the manual design of the buildings has taken much more time (refer to Table 7.4) Compared to the time by STAAD Pro design software. The detailed design of the slabs, stairs, arches and the sections have relatively consistent results.
Table 7.28 : Time, in Minutes, and Percentage of Time for Detailed Structural
Design Based on STAAD Pro Design Software (One Floor Buildings)
ACTIVITY
1. Columns' detailed design
2. Plinth beams' detailed design
3. Floor beams’ detailed design
4. Slabs' detailed design
5. Footings' detailed design
6. Stair case detailed design
7. Arches' detailed design
8. Sections' detailed design
1A
Time
% of
Time
Time
1B
% of
Time
1C
Time
% of
Time
99 33.22
99 28.86 132 36.46
46 15.44
33 9.62 32 8.84
42
47
32
11
14
7
BUILDING REFERENCE
14.09
15.77
10.74
3.69
4.70
2.35
53
53
60
16
20
9
15.45
15.45
17.49
4.66
5.83
2.62
52
54
53
14
12
13
14.36
14.92
14.64
3.87
3.31
3.59
Total 298 100 343 100 362 100
Similar to the preliminary design stage, the percentages of the detailed structural design members (Table 7.28) have been combined with the percentages of the detailed structural drafting (Table 7.5) to form a complete set of detailed structural design drawings. The result of these combined percentages of time

217 including the mean and the standard deviation for each of the structural members is shown in Table 7.29. The calculation for the combined percentages for the detailed design stage is similar to the one that has been previously discussed. As it can be seen from Table 7.6 and Table 7.29, the variations on the results of the three buildings have turned up more for manual calculations compared to STAAD Pro design method and being the highest for columns’ detail. In addition, the majorities of such variations happened to be for building reference 1C. This is possible due to the number of the structural members to be designed for building 1C compared to the other two buildings.
Table 7.29 :
Percentage of Time for Detailed Structural Design and Drafting Based on STAAD Pro Design Software (One Floor Buildings)
ACTIVITY
1A
BUILDING
REFERENCE
1B 1C
% of
Time
% of
Time
% of
Time
1. Columns' details
20.72 18.57 28.06 22.45 4.98
2. Plinth beams' details
15.74 13.46 9.35 12.85 3.23
3. Floor beams’ details
15.14 16.87 13.55 15.18 1.66
4. Slabs' details
10.96 9.88 10.48 10.44 0.54
5. Footings' details
7.37 11.07 9.68 9.37 1.87
6. Stair case details
9.76 11.07 11.13 10.65 0.77
7. Arches' details
14.14 13.12 9.35 12.21 2.52
8. Sections' details
6.18 5.96 8.39 6.84 1.34
Figure 7.14 shows the comparison between the estimated percentages of time to design main structural members for the three buildings of one floor each at the detailed design stage. It is clear from this figure that the results for detailed design of columns, plinth beams and footings are not very consistent to each other with

218 maximum percentages are being for columns' detailed design. The overall characteristic of Figure 7.14 in term of the distribution of the percentages of time along the structural members is identical to Figure 7.2 which was based on manual calculations yet in different magnitudes. Furthermore, unlike the preliminary design of these buildings where the maximum percentages of time were recorded for footings’ locations and sizing, at the detailed design the maximum percentages were being for columns’ detailed design.
30%
25%
Bld. 1A
Bld. 1B
Bld. 1C
20%
15%
10%
5%
0%
Arc hes'
Colu det. mns desi
Fl. b gn
' det eam
. de
Foo ting s' de sign t. de
Plin s' de sign th b t. de
Sec eam sign tion s' de
Slab s' de t. de s' de t. de sign
Stair t. de sign s' de sign t. de sign
Structural Members
Figure 7.14 : Percentages of time for the one floor buildings at detailed design stage based on STAAD Pro design Software
Figure 7.15 gives a graphical comparison between the mean percentages of time that have been obtained by the manual design and the ones obtained by STAAD
Pro Design software for the three buildings of one floor each at the detailed design stage. It is clear from the figure that the manual design has taken more time for columns' and floor beams’ details and has taken less time for all other structural

219 members compared to the one by STAAD Pro design software. It can be also noted from this figure that there are not much variations in the results of these members except the one for columns' details. The high percentage of time for the columns' detailed design in the manual method is contributed to the lengthy calculations involve in the manual analysis part for these columns. On the other hand, the two methods have resulted almost similar percentages of time for all other structural members.
40%
By Manual Design
By STAAD Pro Software
35%
30%
25%
20%
15%
10%
5%
0%
Colu mns
Plin th b
' deta ils
Fl. b eam s' de eam tails
Sla s' de bs' d tails
Foo etails ting
Arc s' de hes' tails
Sec deta ils tion s' de
Sta irs' d tails eta ils
Structural Members
Figure 7.15 : Comparison between manual design Vs. STAAD Pro design software for the three buildings of one floor each at detailed design stage

220
7.8.3
Preliminary Design and Drafting by STAAD Pro for Two Floors
Buildings
Table 7.30 displays the time that was needed for designing main structural members at preliminary design stage for the three buildings of two floors each as well as the corresponding percentages of time for these structural members. The result of the obtained data does not show much variation on the percentages of time for the structural group members among the buildings. Nevertheless, most of the recorded time at this stage for this group of buildings was spent for floor beams.
This is due to the fact that when the time for modeling the structure has been distributed to all members, the beams for the two floors have taken twice the time of other individual members.
Table 7.30 :
Time, in Minutes, and Percentage of Time for Preliminary Structural
Design Based on STAAD Pro Design Software (Two Floors Buildings)
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and
sizing
3. Floor beams’ locations, loads’
calculations and sizing
4. Load calculations on slabs
And sizing
5. Load calculations on footings
And sizing
6. Stair case preliminary design
7. Arches preliminary design
BUILDING REFERENCE
Time
2A
% of
Time
Time
2B
% of
Time
2C
Time
% of
Time
66 19.76
81 18.28 58 17.90
40 11.98
111 33.23
49 11.06 48 14.81
125 28.22 99 30.56
12 3.59 20 4.51 13 4.01
55 16.47
14
17
4.19
5.09
91 20.54 62 19.14
27
29
6.09
6.55
15
18
4.63
5.56 preliminary 19 5.69 21 4.74 11 3.40
Total 334 100 443 100 324 100
With a similar approach to the previous buildings, the total percentages of the preliminary structural design members have been combined with the percentages of

221 the preliminary structural drafting of Table 7.8 for the three buildings so that a set of preliminary design was produced. Table 7.31 illustrates the obtained percentages when the design and the drafting were merged.
It is clear from this table that the obtained data is homogenous since the percentages of time to design the structural members at each building are being near their mean values. Even though the footings have the highest dispersion of time from their mean, their differences are minimal. In general, the result of this group of buildings turned up to be more consistent than the results of other previous buildings of one floor. This has possibly been a factor of the similarities of the buildings in term of their difficulties and their structural arrangements and hence their level of designing and detailing.
Table 7.31 :
Percentage of Time for Preliminary Structural Design and Drafting
Based on STAAD Pro Design Software (Two Floors Buildings)
ACTIVITY
2A
BUILDING
REFERENCE
2B 2C
% of
Time
% of
Time
% of
Time and 16.78 14.98 16.42 16.06 0.95
2. Plinth beams' locations and
sizing
9.53 10.38 12.10 10.67 1.31
3. Floor beams’ locations and sizing 22.81 20.87 22.96 22.21 1.16 locations sizing 2.62 3.30 3.21 3.05 0.37
6. Stair case and 16.63 21.34 16.30 18.09 2.82
9.44 10.26 10.00 9.90 0.42
11.68 10.97 11.11 11.25 0.38
10.51 7.90 7.90 8.77 1.51
The percentages of time that have been presented in Table 7.31 are shown graphically in Figure 7.16 so that better comparison between the obtained results for

222 the three buildings can be easily observed. The figure shows clearly the distribution of the time that was spent to carry out the preliminary design of the structural members with maximum percentages can be noticed in which they were recorded for the floor beams’ location and sizing followed by the footings. The slabs came in the lower part of this graph.
The consistency of the results between the three buildings can be easily seen from the graph. There are almost no variations in the result except for the footings' location and sizing in which the percentage of time for building 2B varies reasonably compared to the values for the other two buildings. The three buildings came up to have very close percentages of time for their arches, slabs and their stairs.
25%
Bld. 2A
Bld. 2B
Bld. 2C
20%
15%
10%
5%
0%
Structural Members
Figure 7.16 :
Percentages of time for the two floors each at preliminary design stage based on STAAD Pro design Software

223
To compare the result that has been obtained by the manual calculations with that obtained by STAAD Pro software for the two floors buildings at the preliminary design stage, Figure 7.17 shows such comparison. With a glance look to this figure, the manual design resulted with higher mean percentage of time for footings' design and less values for columns and plinth beams. It can be seen from the figure that there is a large difference on the mean percentages of time between the two methods.
This is mainly due to the fact that by using the manual method, a lengthy calculation is required to come up with preliminary design for the footings which is not the case for the STAAD Pro design. The two methods did not show much variation in the percentages of the time for the arches, sections, slabs and for the stairs.
30%
By Manual Design
By STAAD Pro Software
25%
20%
15%
10%
5%
0%
Colu mn
Plin s' lo th b cat.
& s
Fl. b eam izin s' lo g eam cat.
Slab s' lo
& s s' lo cat.
& s izin g
Foo cat. izin
& s g ting s' lo izin g
Stai rs cat.
Arc
& s izin g hes
Structural Members
Sec tion s
Figure 7.17 : Comparison between manual design Vs. STAAD Pro design software for the three buildings of two floors each at preliminary design stage

224
7.8.4 Detailed Design and Drafting by STAAD Pro for Two Floors Buildings
The time and its percentages for detailing the preliminary design of the structural members for the two floors buildings are shown in Table 7.32. Examining this table gives an idea about the variations in the results that have taken place especially for the detailed design of plinth beams between building 2B (4.75%) and building 2C (7.55%), slabs' detailed design between building 2B (29.09%) and building 2C (13.8%) and footings' detailed design between building 2B (12.55%) and building 2C (23.44%). It can be observed that there is much variation between building 2A and building 2C.
Table 7.32 :
Time, in Minutes, and Percentage of Time for Detailed Structural
Design Based on STAAD Pro Design Software (Two Floors Buildings)
ACTIVITY
1. Columns' detailed design
2. Plinth beams' detailed design
3. Floor beams’ detailed design
4. Slabs' detailed design
5. Footings' detailed design
6. Stair case detailed design
7. Arches' detailed design
8. Sections' detailed design
47
99
18
16
10
BUILDING REFERENCE
Time
2A
% of
Time
Time
2B
% of
Time
2C
Time
% of
Time
132 28.21
165 31.37 132 34.38
33 7.05 25
10.04
113 24.15
21.15
3.85
3.42
2.14
66
153
66
14
19
18
4.75 29 7.55
12.55
29.09
12.55
48
53
90
12.50
13.80
23.44
2.66 14 3.65
3.61 10 2.60
3.42 8 2.08
Total 468 100 526 100 384 100
Table 7.33 displays the percentages of time that were needed for designing and drafting main structural members at detailed design stage for the three buildings of two floors each. The result of the obtained data shows some variations on the percentages of time for the structural group members among the buildings. Much of

225 such variations have been caused possibly by the variations at the detailed design stage as discussed previously rather than at the detailed drafting stage. When the two values of the detailed design and drafting merged together, they resulted in some differences in the combined values. Nevertheless, such differences are still reasonable for this type of data collection and for such a method of designing the structure (STAAD Pro software design method). One of the main contributions to these types of variations is the time factor to produce the modeling of a structure. If the model does not run at the first time in one of the buildings, more time will be added to the modeling time and hence result in variations compared to other buildings with error free in their STAAD Pro analysis and design parts.
Table 7.33 : Percentage of Time for Detailed Structural Design and Drafting Based on STADD Pro Design Software (Two Floors Buildings)
ACTIVITY
BUILDING
REFERENCE
2A
% of
Time
2B
% of
Time
2C
% of
Time
21.22 25.75 24.83 23.93 2.40
3. Floor beams’ details
6. Stair case details
8.92 5.46 8.61 7.67 1.91
12.84 14.30 14.19 13.78 0.82
16.35 20.81 10.30 15.82 5.27
14.32 9.75 16.72 13.60 3.54
8.24 6.89 10.30 8.48 1.72
10.00 9.36 9.12 9.49 0.45
8.11 7.67 5.91 7.23 1.16
The variations in the result of the above table can be seen clearly in Figure
7.18. The figure shows clearly the distribution of the time that was spent to design and detail the structural members by STAAD Pro design software. In addition, it is noticeable to see how the values vary from each other particularly the ones for

226 detailed design of footings and roof slabs. Similarly, the percentages of time for detailed design of the arches, floor beams, the sections and the stairs have reasonable consistent to each other and tend to be in the lower range in the distribution of the time between the members. Unlike the preliminary design stage of these buildings in which the floor beams turned out to have the maximum percentage of time, at this stage the columns' detailed design came on top of the curve and hence have got the maximum percentage of time. Furthermore, compared the result of this stage with previously discussed stages of one and two floors buildings based on STAAD Pro design, this stage have shown more dispersion in the result of the three buildings.
30%
25%
Bld. 2A
Bld. 2B
Bld. 2C
20%
15%
10%
5%
0%
Arc hes' de
Col um t. de ns
' de sign
Fl. be am t. d esig n
Foot s' d ings et. de
' de
Plint h b eam s' d sign t. d esig
Sec tions n
Slabs
' de et. de
' de t. de sign
Stai rs' de t. de sign sign t. d esign
Structural Members
Figure 7.18 :
Percentages of time for the two floors buildings at detailed design stage based on STAAD Pro design Software

30%
25%
20%
15%
10%
5%
227
Figure 7.19 below gives a closed comparison between the mean percentages of time that have been obtained by the manual design and the ones obtained by
STAAD Pro Design software for the three buildings of two floors each at the detailed design stage. It is clear from the figure that the manual design has taken more time for the detailed design of the columns and the plinth beams and less time for all other structural members compared to the one by STAAD Pro design software. It can be also noted from this figure that there are some variations in the results of the columns' and slabs' detailed design compared to the variations of other members.
The high percentage of time for the columns' detailed design in the manual method is contributed to the lengthy calculations involve in the manual analysis part.
40%
By Manual Design
By STAAD Pro Software
35%
0%
Col um ns' d
Plin th b eta ils
Fl. b eam s' d eam etai ls
Sla s' d eta bs' d ils
Foo etai ls ting s' d
Sta irs' d etai ls
Arc etail s hes
Sec tio
' de tails ns' d etail s
Structural Members
Figure 7.19 :
Comparison between manual design Vs. STAAD Pro design software for the three buildings of two floors each at detailed design stage

228
7.9
Suggested POF Method for Assessing the Fee of the Structural Design
Changes
The result of the data analysis that have been achieved for the twelve number of buildings ranging from one floor to four floors can be used to suggest a method for assessing the fee of the structural design changes when they occur. A name has been assigned for this method to be “Percentage of Original Fee” (POF) method.
This name reflects the basis in which the method has been derived from. Hence, POF method is based on the mean average percentages of time that have been estimated for each type of buildings and based on manual calculations. To use this method, a proposal has been made to consider two stages of design. These are preliminary design stage and detailed design stage. The rationale behind splitting the design to these stages is being that it is likely to have design changes due to various reasons at early stage of the design as well as at later time and hence the amount of the changes can be assessed at the time when they occur. Table 7.34 shows the obtained mean average percentages of time for the preliminary structural design associated to each group of buildings under this study. It is suggested to use these percentages as coefficients for better matching with the forthcoming proposed mathematical expression.

229
Table 7.34 : Percentage of Time for Preliminary Structural Design and Drafting
(One Floor to Four Floors Buildings)
ACTIVITY
1. Columns' locations and sizing
2. Plinth beams' locations and sizing
One
Floor
Build.
Coeff.
(% of
Time)
13
Two
Floors
Build.
Coeff.
(% of
Time)
12
7 7
Three
Floors
Build.
Coeff.
(% of
Time)
12
Four
Floors
Build.
Coeff.
(% of
Time)
12
7 7
3. Floor beams’ locations and sizing
4. Slabs' locations and sizing
5. Footings' locations and sizing
6. Stair case
7. Arches
8. Sections
14
3
30
11
12
10
23
3
28
9
10
8
24
2
30
8
10
7
26
2
31
7
8
7
Similarly, Table 7.35 shows the obtained mean average percentages of time for the detailed structural design associated to each group of buildings under this study.
The fee of the structural design changes either at preliminary or detailed design stage then can be assessed by the following expression:
Fee of Design Changes
=
⎡
⎢⎣ Coeff .
X
NMM
TNM
⎤
⎥⎦ X OCC
7.1
Where:
Coeff .. to be obtained from Table 7.34 (for preliminary design) or from Table
7.35 (for detailed design) wherever applicable
TNM
: Total Number of the structural Members before the changes which can
be estimated as follow:
For columns : Total number of columns at footings’ level before the
changes

230
For beams : Total number of spans between beams’ supports before
the changes
For slabs : Total number of slabs’ panels before the changes
For Footings : Total number of isolated and/or combined footings
before the changes
For arches & sections : Total number of each before the changes
NMM : Number of the Modified structural Members Corresponding to TNM
OCC : Original Contract Fee, (either preliminary or detailed design fee)
Table 7.35 :
Percentage of Time for Detailed Structural Design and Drafting (One
Floor to Four Floors Buildings)
ACTIVITY
1. Columns' details
One
Floor
Build.
Coeff.
(% of
Time)
35
Two
Floors
Build.
Coeff.
(% of
Time)
32
Three
Floors
Build.
Coeff.
(% of
Time)
31
Four
Floors
Build.
Coeff.
(% of
Time)
33
2. Plinth beams' details 11 10 10 10
3. Floor beams’ details
4. Slabs' details
5. Footings' details
6. Stair case details
7. Arches' details
8. Sections' details
21
7
6
7
8
5
22
10
9
6
6
5
25
6
13
5
6
4
24
7
9
6
6
5
The above expression (equation 7.1) is close to the expression that has been developed by Eddy and Amlan (2003) for measuring the total direct cost for projects.

231
In their expression, they have defined the Total Direct Cost in time t (TDC t
) as the sum of the direct costs for all activities in the project, thus:
TDC t
= a
i
= 1
C i
, t
Where C i,t
= direct cost of activity i in time t; and a = total number of activities in the project. They have further defined the direct cost (C i,t
) of activity i in time t as the sum of the cost of materials; labour, and equipments.
To compare the work done by Eddy and Amlan (2003) with equation 7.1, both equations measure the costs of activities within allocated time. However, equation 7.1 assesses the fee of design changes for re-designing structural members
(activities) within pre-defined percentage of time (coefficients) for each group of structural members.
7.10 Illustration for Using POF Method
7.10.1 Example 1, One Floor Building
The detailed structural design of one floor building (building ref. 1A) has been modified. The original and the modified structural plans at plinth beams level are shown in Figure 7.20 and Figure 7.21 respectively. With reference to Figure
7.20, the original structural design consists of 27 columns and are marked with numbers from 1 to 27 while the original number of plinth beams is 42 and are numbered in parenthesis from (1) to (42). The effective columns and plinth beams due to these design changes are shown in Figure 7.21 and numbered from 1 to 12 for the columns and from (1) to (19) for the plinth beams. Similarly, Figure 7.22 shows

A C D E F G H J L
9
4
3
1
Figure 7.20 : Original Plinth (Ground) Beams Plan
9
4
3
8
7
6
5
8
7
6
5
A D E G H L
1
Figure 7.21 : Modified Plinth (Ground) Beams Plan
232

233
9
A C
S 2
E F G
S 1
H J
S 3
L
8
7
5
S 2
S 2
S 1
S 1
S 3
S 3
4
3
S 1
S 1
S 3
1
Figure 7.22 : Original Roof Slabs/Beams Plan
A E G H L
9
8
7
5
4
3
1
3
2
1
Figure 7.23 : Modified Roof Slabs/Beams Plan

234 the original plan of the roof beams/slabs and its modification is shown in Figure
7.23. Hence, in the original design there are 38 floor beams, 12 slabs' panels and in the revised design there are 19 roof beams and 4 floor slabs' panels. Isolated and combined footings are provided for both original and the modified design. There were no changes made to the stair, the arches and the sections. Although, the foundation of the structure is affected by the changes, their numbers and detail are not shown since they are not required in the calculation. The structural design consultancy fee as in the original contract is USD$ 4,800 for the preliminary structural design and USD$ 3200 for the detailed structural design. Thus, from Table
7.34, the coefficients for modifying the locations and sizing of the columns, plinth beams, floor beams, slabs and footings are 13%; 7%; 14%; 3% and 30% respectively. Similarly, the coefficients of Table 7.35 for their counterpart modified design are 35% for columns; 11% for plinth beams; 21% for floor beams; 7% for slabs and 6% for footings. Thus, the fee of modifying the original structural design based on equation 7.1 above is:
Fee of the preliminary structural design changes =
[
13
100
X
X
12
27
+
7 X
X
10
+
14 X
X
17
+
3 X
X
3
+
30
100 42 100 38 100 12 100
Fee of the detailed structural design changes =
X
X
12
27
]
[
35
100
X
X
12
27
+
11
100
X
X
10
42
+
20
100
X
X
17
38
+
7
100
X
X
3
12
+
6
100
X
X
X
12
27
]
4 , 800
X 3 ,
=
200
1
=
, 334
1 , 009
Total fee of the structural design changes = USD$ 2,343
7.10.2 Example 2, Two Floors Building
The detailed structural design of two floors building (building ref. 2B) has been modified. The original and the modified structural plan at ground floor roof slabs/beams level are shown below in Figure 7.24 and Figure 7.25 respectively.

Figure 7.24 :
Original Ground Floor Roof Slabs/Beams Plan
Figure 7.25 : Modified Ground Floor Roof Slabs/Beams Plan
235

Figure 7.26 :
Original First Floor Roof Slabs/Beams Plan
Figure 7.27 : Modified First Floor Roof Slabs/Beams Plan
236

237
With reference to these figures, there were 12 columns modified out of 30 in the original design. For illustration, these columns are listed in numbers from 1 to 30 in Figure 7.24 and from 1 to 12 in Figure 7.25. Similarly and within the same figures, it can be seen that out of total 46 ground floor roof beams 19 have been affected by the modification as well as 5 slabs' panels out of 15. It can also be seen that there was a change in the stair design. Modifications have also taken place at first floor roof slabs/beams level in which the original design is shown in Figure 7.26 and the modified one is shown in Figure 7.27. Referring to Figure 7.26, there were
45 beams and 15 slabs' panels at this level. Figure 7.27 shows the number of modified beams and slabs compared to the original design. Hence, 19 beams and 5 slabs' panels were modified. In addition, it was necessary to change the design of two arches out of 3 and 1 section out of three. Isolated and combined footings are provided for both original and the modified design. No changes have been made to the plinth beams.
Although, the foundation of the structure is affected by the changes, their numbers and detail are not shown since they are not required in the calculation. The structural design consultancy fee as in the original contract is USD 6,400 for the preliminary structural design and USD$ 4800 for the detailed structural design.
Thus, the fee of modifying the original structural design based on equation 7.1 above and the coefficient of Table 7.34 and Table 7.35 is :
[
Fee of the preliminary structural design changes =
12
100
X
X
12
30
+
23
100
X
X
38
91
+
3
100
X
10
X
30
+
28
100
X
12
X
30
+
9
100
X
X
1
1
+
10
100
X
X
2
3
+
Fee of the detailed structural design changes =
8
100
X
X
1
3
]
X
6 , 400 = 2 , 876
[
32
X
100
X
12
30
+
22
100
X
X
38
91
+
10
100
X
X
10
30
+
9
100
X
12
X
30
+
6
100
X
X
1
1
+
6
100
X
X
2
3
+
5
100
X
X
1
3
] X 4 , 800 = 1 , 948
Total fee of the structural design changes = USD$ 4,824

238
7.11 The Result of the Validation
The results of the obtained responses in term of Main Scores and categories for each stated observation are presented in Table 7.36. As it can be seen from this table, the consultant engineers that have participated in the questionnaire were
“mostly agreed” on the principle of the POF method, its methodology and on the estimated coefficients for each structural members as presented on Tables 7.34 and
Table 7.35. Comments that have been raised by the respondents for these observations included a need for continuity of works to carry out the design changes along with executing the original scope of work so that no idle time shall be wasted and all external factors such as co-ordination time, level of involving the top management at the time of introducing the changes and the possibility need for more specialized engineers that may lead to extra man-hours over the original estimated time.
One of the respondents has made some comments against the proposed coefficients of Tables 7.34 and Table 7.35. He claimed that the actual time in the project when a change is introduced has an effect on how quickly re-design can be carried out. During the design phase, the engineers and the draftsmen are familiar with the project, all information is readily available and the implication of a change can be easily recognized. Later during construction, the effect of the changes is more disruptive. The engineers and the draftsmen are possibly working on other project. Design information and drawings could be filed away and the engineers available to take action on the change may not be the same person who did the original design. The engineers then need to take time to become familiar with the building arrangement. Secondly, when the structure is changed in some way, it might be first necessary to consider if the existing design is still adequate. If not, then there will be a need to carry out re-design for the elements which are found to be inadequate. The re-design will be a function of the original design but the checking of the existing arrangement is extra. With the above comments on mind, it is reasonable to assume that the original contract fee includes fee for such factors and hence to relate the fee of the design change proportionally to the original fee is not a deviation to this assumption.

239
Table 7.36 : The Questionnaire Result for the Validation POF Method
1)
2)
3)
4)
5)
6)
Observation
The principal of the POF method is acceptable
The adopted methodology for the POF method is
Acceptable
The definitions of the parameters used in the
mathematical expression are acceptable
The proposed POF method is practical
The proposed POF is suitable for assessing the consultancy fee of the structural design changes
Mean
Score
Consultants'
Agreement
4
3.8
The proposed coefficients in Tables 1 and Table 2 are
Reasonable
3.6
4.0
3.6
Mostly
Agree
Mostly
Agree
Mostly
Agree
Mostly
Agree
Agree in
Average
Mostly
Agree
7)
8)
The proposed POF is only valid for limited type of projects
There is no confidence yet in the proposed POF method
3.2
2.4
Agree in
Average
Slightly
Agree
9)
10)
The POF method could be better if it is based on computer software rather than manual calculations
In summary, the POF method is acceptable
3.2
Agree in
Average
Mostly
Agree
11)
The proposed POF method can be suggested to be in the contract documents for the structural design changes
4.2
Mostly
Agree
The respondents were also "mostly agreed" on the definitions of the parameters used in the mathematical expression, on its suitability and were "mostly agreed on that the method can be used in the contract documents for assessing the consultancy fee of the structural design changes.
The participated consultant engineers showed less level of agreement "agreed in average" on the observations related to the practicality of the method and also in

240 the fact that the POF method is only valid for limited type of projects. One of the respondents claimed that the method is practical only for the type of reference building on this research or a like but may not be as practical for other buildings.
This might be true to some extend and as a result this is one of the limitations of the
POF method. Furthermore, there was an "average agreement" in which the POF method could be better if it was based on computer software rather than manual calculations. The participated consultant engineers have shown dispersed view to this point in the fact that one respondent "disagree", the second one "slightly agreed", the third "agreed in average" and both the forth and fifth "strongly agree" that the method could be better if it was based on computer software. Nevertheless, the respondents have shown a good level of confidence in the method as it can be seen from the score of this observation. However, respondents have raised the need for testing and trying the method in order to assess the predicted fee by using the method with actual man-hours' fees that are needed to carry out the changes.
7.12 Chapter Summary
(1) The chapter presented the detail of the actual data that has been obtained for this study and is needed to develop the POF method of assessing the fee of the structural design changes.
(2) As part of the research methodology of this work, twelve different types and sizes of reinforced concrete buildings have been designed manually as well as by
STAAD Pro software and drafted by AutoCAD software. The timing for each structural activity has been recorded and reported in tabulated forms.
(3) The obtained data for designing the buildings under this research work has been divided into two stages. The first stage is being for the preliminary design and drafting while the second stage is being for the detailed design and drafting.
(4) The result that has been achieved and presented in this chapter for the twelve buildings has been used to develop POF method for assessing the fee of the structural design changes. This method is presented in a form of mathematical expression.

241
(5) The POF method has been developed in this chapter based on manual calculations. Design by STAAD Pro software has been also performed on one and two floors buildings for comparison with the manual design.
(6) Two examples have been given in the chapter to illustrate the practical use of
POF method.
(7) The POF method has been validated by a questionnaire survey. The result has shown a satisfaction among the participated professionals.

CHAPTER 8
8.1 Introduction
DEVELOPMENT OF THE GUIDELINES
FOR MANAGING DESIGN CHANGES
This chapter provides the development process of the guidelines. It presents firstly proposed set of guidelines for improving the consultancy design documents and then another proposed set of guidelines to manage their claims highlighting the basis of each suggested guideline. The chapter also furnish the procedure for validating the developed guidelines that has been considered for this part of the research. In this regard, Delphi technique has been used in the chapter as a tool for the validation. Hence, a theoretical background of the Delphi method was given in
Chapter 5. The chapter ends up with providing the details and the results of the three
Delphi rounds of questionnaires that have been conducted with seven professionals working in the engineering consultancy firms in the Sultanate of Oman.
8.2
Initial List of Guidelines for Improving Consultancy Design Documents
The following is a preliminary list of guidelines for improving the consultancy design documents with respect to managing the design changes in RC buildings which have been developed to reduce the chances caused by disputing the claims associated with design changes. The recommendations of the American

243
Collage of Cardiology (ACC), Section II: Tools and Methods for Creating
Guidelines (2004) has been followed in constructing the guidelines (refer to Chapter
5, Section 5.8) with cross reference to the result of this research work but have been modified as deemed necessary. In particular, from the results of the literature reviews, interviews, case studies and the questionnaire survey that all were presented in the previous part of this research. Each guideline has been developed based on the following:
Guideline 1: The scope of the engineering consultancy services to be provided shall be clearly defined in the consultancy contract documents. The scope of the work shall be divided into separate sections according to the nature, similarity and complexity of each part of the project (e.g. feasibility studies, similar buildings, roads, landscaping, building services, boundary walls, etc). Each defined scope of services such as above examples shall have its own fee item
This guideline has been identified from the result of the interviews as a reply to why design changes occur. The respondents to this question have stated that design changes in many cases take place when the initial scope of work is not clear and not well defined in the tender documents. Furthermore, the respondents to the questionnaire survey have mostly agree that in order to minimise the avoidable design changes (Table 6.20, item j), a clear and comprehensive design brief at early stage shall be provided.
Guideline 2: Each consultancy scope of work shall be divided into preliminary design phase and detailed design phase wherever applicable. Each phase shall be clearly defined in the consultancy contract document and shall have its own fee item.
This guideline has been extracted from the "Standard Form of Agreement and
Conditions of Engagement for Consultancy Services and Civil Engineering Works,
Sultanate of Oman (1987)" in which the scope of consultant services in this standard includes preliminary design stage and detailed design stage among other stages (refer to Chapter 4, section 4.6 of this research). The developed POF method on this study for assessing the fee of the structural design changes in RC buildings was also based on these two stages of the design phases.

244
Guideline 3: Clear definition for what is to be considered design changes shall be included in the consultancy contract document
This guideline has been extracted from the case study three (section 3.3.3) in which a classification for design changes has been included in the contract document.
In this respect, the design changes have been classified to be either minor (should have no claims) or major (might cost money).
Guideline 4: Clear method for assessing the fee of the design changes shall be included in the consultancy contract document at the tender stage
This guideline built up from the identification of the existing methods of charging for consulting services that have been highlighted in the literature review
(Chapter 3, section 3.6), in the result of the interviews with the professionals
(Chapter 6, Table 6.4, responses to question no. 8), in the result of the case studies
(Chapter 6, section 6.3.8) and in the result of the questionnaire survey (Chapter 6,
Table 6.22).
Guideline 5: For large scale projects especially the fast track ones where the construction work is required to start before completion of the design, it is advisable to make a provision in the consultancy contract document at the tender stage to allocate certain design members specifically for design changes and to be paid in agreed full/part time monthly basis for a particular duration. This requirement shall be reviewed in regular basis to make any adjustment if deemed necessary
This guideline formulated from case study two and case study three. In these case studies, provisions have been given in the contract documents to allocate certain design members to carry out the design changes for a specified period of time. This approach has reduced the number of claims dramatically as reported in the case studies.

245
8.3
Initial List of Guidelines for Managing the Claims of Design Changes
The forthcoming guidelines have been developed based on extensive consultations with the professionals who are broadly familiar with the general subject of engineering consultancy practice and in particular on the issues associated with the design changes. Reference for constructing the guidelines has been made to the recommendations giving by the American Collage of Cardiology (ACC), Section II:
Tools and Methods for Creating Guidelines, 2004 (refer to Chapter 5, Section 5.8)
Delphi technique has been used to establish an initial list of guidelines (Delphi round one) and to justify the validity of each guideline (Delphi round two and three).
These guidelines have been formulated with an intention to reduce the disputes as a result of the claims. The basis for the guidelines are to provide the required justification for carrying out the design changes (guideline 1), to provide good documentation process as a back up for the claims (guidelines 2, 3, 4 and 6) to minimise the chances for disputes that may arise from unpredictable impact of the design changes (guideline 5) and to avoid the lengthy process for evaluating the claims (guidelines 7 and 8). The initial guidelines for managing the claims of design changes are:
Guideline 1: An initial agreement and formal instructions to carry out the design changes shall be provided and approved by the authorised persons
Guideline 2: Each claimed design change shall be given a chronological reference number and date
Guideline 3: Each claimed design change shall be well documented in a pre-defined standard form. The form shall include the project name, the contract number, the variation reference number, date of issuing the variation, the name and the designation of the person who issued the change, brief details of the reasons for the changes and the nature and the extent of the changes.
Guideline 4: Each claim shall be submitted along with all relevant drawings and/or calculations to the main contact person along with a covering letter (copied to all

246 concerned people) confirming that the design will be revised per the received/verbal instruction.
Guideline 5 : Any possible impact on fee and program due to the design changes shall be highlighted to the client and agreed as early as possible
Guideline 6: A record shall be kept for the status of the completed design at the time of introducing the changes. This shall include all the drawings and calculations before modifying the design as a back up for the claims
Guideline 7: As for additional works, it is advisable to negotiate the fee of the design and agree on a lump- sum basis
Guideline 8 : The fee of each claimed design change shall be evaluated and settle down as early as possible. It is advisable not to accumulate un-settled claims to very late stages
8.4 Validation of the Developed Guidelines
To provide a meaningful result of this study and to be in line with the scientific approaches to present the findings of the research work for practise, the developed guidelines that have been presented in the previous sections need to be validated by the concerned professionals. The intention of the validation process is to assess the practicality of the guidelines, their suitability for real life implementation and their effectiveness. The Delphi technique found to be the most appropriate method for the validation of the developed guidelines and hence has been adopted. Theoretical background of the Delphi Method has been provided in
Chapter 5 (Research Methodology). The following sections present the result of the validation for the developed guidelines using the Delphi Method.

247
8.5 The Delphi Round One Questionnaire
The first round of the Delphi questionnaire, accompanied by an invitation letter, was sent to nine professionals. The letter explained the purpose of the research, and the participants were informed that there would be three rounds of questionnaires. In the first round of the Delphi method, initial sets of guidelines that have been presented in section 8.2 and section 8.3 of this chapter have been provided and the participants were asked to comment and/or to make modification on each guideline if deemed necessary. In addition, the participants have been requested to provide additional guidelines that in their opinions are necessary for improving the consultancy design contract documents as well as to provide supplementary guidelines for managing the claims of the design changes. Appendix F shows the round one questionnaire that has been handed over to the participated professionals.
Out of the nine selected professionals, only seven have replied. As a result of this round, only the professionals who returned their answers to the questionnaire have been considered for the successive Delphi rounds.
8.5.1 The Result of the Delphi Round One Questionnaire
A list of eight guidelines for improving the consultancy design documents with respect to managing the design changes in RC buildings and another list of also eight guidelines for managing their claims have been developed as a result of this round. The professionals have taken 16 days to complete this round and to return their replies. This period is longer than anticipated. The rationale behind taken this much time as claimed by the participated professionals is being the request for additional guidelines that need more time for thinking and writing. Consequently, the successive Delphi rounds were made simpler for the professionals in the sense that writings were eliminated and only ticking boxes were considered to utilise the professionals' time and to get positive replies within reasonable time period. There were some guidelines which had not been suggested by the panel of professionals but were identified at later stage. Nevertheless, they have been included in the successive rounds of the Delphi questionnaires. The professional have provided

248 occasionally some comments to each guideline which have resulted in enhancing and rephrasing the preliminary list of the guidelines. In addition, it was necessary to divide some of the guidelines into separate guidelines as perceived by the respondents. None of the professionals has provided additional guidelines.
8.6 The Delphi Round Two Questionnaire
In this round, a set of practical guidelines that have been obtained from round one were finalised to reflect the comments of the participated professionals. The resulted set of guidelines has been tabulated in this second round. The Delphi round two questionnaire is shown in Table 8.1 and Table 8.2. The professionals were asked to indicate the relative importance level for each guideline that has been identified in round one of the Delphi survey, using a simple 3-level scale: very important, important and not important. The result of round one questionnaire survey was attached for the professionals’ reference.
8.6.1 The Result of the Delphi Round Two Questionnaire
All professionals who participated in this round of the Delphi survey have returned their replies within the allocated time, in many cases within the same day due to the simplicity of the questionnaire format. The result of this round shows that all the identified guidelines are either very important or important. Hence, there was only one guideline considered not important one at this round. However, all the guidelines have been considered for the next Delphi round. Table 8.1 and Table 8.2 show the obtained lists of guidelines with an indication of relative importance level of each guideline for improving the consultancy design documents with respect of the design changes and the relative importance level of each guideline for managing the claims of the design changes as perceived by the seven professionals.

249
Table 8.1
: Delphi Round Two Results: Relative importance level of each guideline for improving the consultancy design documents
Guideline
(1) The scopes of the engineering consultancy services to be provided shall be clearly defined in the consultancy contract documents
(2) Any existing information related to the proposed work shall be clearly defined in the consultancy contract documents and shall be available during the tender stage including the history of the site, pervious site investigations, existing structures, underground facilities, etc.
(3) Any restrictions on the programme of the work, on the flow of the design information and any special design requirements shall be clearly defined in the consultancy contract design documents.
(4) The consultancy scope of works shall be divided into separate sections according to the nature, similarity and complexity of each part of the project (e.g. feasibility studies, similar buildings, roads, landscaping, building services, boundary walls, etc)
100%
7 - -

Table 8.1
: Continue
Guideline
250
(5) Each defined consultancy scope of work shall be divided into a preliminary design phase and a detailed design phase wherever applicable. Each phase shall be clearly defined in the consultancy contract document and shall have its own fee item(s).
(6) A clear definition for what is to be considered design changes shall be included in the consultancy contract document
(7) Clear methods for assessing the fee of the design changes shall be included in the consultancy contract document at the tender stage
(8) For large scale projects, especially fast track ones where the construction work is required to start before completion of the design, it is advisable to make a provision in the consultancy contract document at the tender stage to allocate certain design members specifically for design changes and to be paid on an agreed full/part time monthly basis for a particular duration. This requirement shall be reviewed on a regular basis to make any adjustment if deemed necessary
86% 1 1

251
Table 8.2
: Delphi Round Two Results: Relative importance level of each guideline for the claims of the design changes
Guideline
(1) An initial agreement and formal instructions to carry out the design changes shall be provided and approved by the authorised persons
(2) Each claimed design change shall be given a chronological reference number and date
(3) Each claimed design change shall be well documented in a pre-defined standard form. The form shall include the project name, the contract number, the variation reference number, date of issuing the variation, the name and the designation of the person who issued the change, brief details of the reasons for the changes and the nature and the extent of the changes.
(4) Each claim shall be submitted along with all relevant drawings and/or calculations to the main contact person along with a covering letter
(copied to all concerned people) confirming that the design will be revised per the received/verbal instruction.
(5) Any possible impact on cost and program due to the design changes shall be highlighted to the client and agreed as early as possible
100%
4 3 -

Table 8.2
: Continue
Guideline
252
(6) A record shall be kept for the status of the completed design at the time of introducing the changes. This shall include all the drawings and calculations before modifying the design as a back up for the claims
(7) For additional works, it is advisable to negotiate the fee of the design and agree on a lump- sum basis
(8) The fee of each claimed design change shall be evaluated and settle down as early as possible. It is advisable not to accumulate unsettled claims to very late stages
8.7 The Delphi Round Three Questionnaire
29% 1 5
For the round three Delphi questionnaire survey, one week has been given for the respondents to return back the questionnaire. Most of the replies received within two days. This round consisted of a covering letter with a briefing on the intention of this round as well of the previous rounds. A table with same format as provided for round two questionnaire survey was formulated. The participants were provided with feedback of the results obtained in round two. The number of respondents for each guideline and the respondent’s own reply in the previous round were furnished.
The respondents were asked to re-assess their own previous opinions in light of other

253 replies by the seven professionals. Appendix G shows the format of the round three
Delphi questionnaire survey.
8.7.1 The Result of the Delphi Round Three Questionnaire
There have been no changes on the questions and the format between round two and round three Delphi questionnaire survey. With reference to the guidelines in
Table 8.1 above for improving the consultancy design documents with respect to managing the design changes, only one respondent revised his previous opinion from
"very important" level to "important" level of significant for guideline number four.
Additionally, for guideline number seven, two professionals revised their previous judgement from "Important" level to "very important" level of significant. There have been no changes on the remaining guidelines.
Similarly, few revisions on the opinions have been made on the guidelines for managing the claims of the design changes. Referring to the guidelines in Table 8.2 above, two professionals have changed their opinions on the significant important level for guideline number six to be "very important" guideline rather than
"important" one as previously judged. Furthermore, the important levels of guidelines seven and eight have been revised by one professional each so that the revised opinions are "important" ones instead of the "very important" scoring.
Although there were few revisions on the significant level of the guidelines for Delphi round three questionnaire survey, the overall result of this round has remained consistent with round two in an assumption that both attained opinions of
"very important" and "important" are to be valid guidelines. Accordingly, there was no need to carry out additional Delphi rounds in this case. Hence, the proposed guidelines as presented in Table 8.1 and Table 8.2 are important to be implemented and are expected to improve the consultancy design documents with respect of managing the design changes.

254
8.8 Chapter Summary
(1) This chapter presented guidelines for improving the engineering consultancy design documents on the issues related to design changes and guidelines for managing their claims.
(2) The guidelines have been developed from the outcomes of the literature review; the interviews; the case studies and the questionnaire survey that all were part of this research work.
(3) The guidelines have been formulated based on being important to reduce the disputes as a result of the claims related to design changes, to provide an effective way to manage their occurrences and to improve the procedure for their assessment.
(4) Three rounds Delphi questionnaires' survey have been carried out with seven professionals working in the engineering consultancy firms in the Sultanate of Oman as a tool for validating the developed guidelines.
(5) The result of the validation process gives strong encouragement to recommend the developed guidelines to be implemented by the professionals.

The aim of this research work was to formulate practical procedures for the assessment of the structural design changes so that an enhancement can be made to the existing practice. This issue has not been given yet the necessary attention though its great effect in the construction industry. A collective approach of investigating the issues under this research work led to the establishment of several objectives that helped to achieve the aim of this study. These objectives were to:
(1) Identify the sources, the causes, and the impacts of the design changes on reinforced concrete buildings;
(2) Establish corrective actions and preventive measures to minimise the avoidable design changes;
(3) Identify and evaluate the various methods for assessing the professional fee of the structural design changes and identify their limitations;
(4) Develop an alternative method to assess the fee of the structural design changes for low rise RCC buildings;
(5) Develop guidelines to improve the consultancy design documents; and
(6) Develop guidelines to manage the design changes when they occur

256
In Chapters 2, 3, and 4 of this thesis the findings from literature survey were highlighted. Problems related to causes, sources and impacts of the design changes along the existing methods for managing them were identified (Chapter 2). A general review of the typical consulting engineering services has been provided
(Chapter 3) and a background related to the construction industry in the Sultanate of
Oman was presented (Chapter 4). In order to realise the aim and the objectives of this study, a research methodology has been established in Chapter 5. Several essential tasks identified in this methodology. At the initial stage of this investigation, data has been collected from the industry of the Sultanate of Oman in term of interviews with professionals, case studies and questionnaire survey (Chapter
6). The results of these investigations have justified the need for this research and have identified the limitations of the existing methods for assessing the fee of structural design changes. Data has been established in Chapter 7 that was necessary for the development of the POF method. Practical examples have been provided in the chapter to illustrate the use of the method. The POF method has been validated by a questionnaire survey with seven professionals working in the consulting engineering firms. The result of this validation process shows a very good agreement among the participated professionals that the POF method is practical, efficient and reliable. Set of practical guidelines for improving consultancy design documents and another set of guidelines for managing the claims of design changes have been developed and presented in Chapter 8. These guidelines have also been validated by means of three rounds Delphi method with seven professionals. The result of this validation encourages saying that these guidelines if implemented shall minimise the chances of disputes associated with design changes.
This section contains the conclusions that have been achieved for each objective of this research

257
The results of the literature review as well as the interviews with the professionals working in the construction industry in the Sultanate of Oman and the questionnaire survey have revealed the sources of the design changes. There are:
•
Clients;
•
Design members;
•
Contractors;
•
Suppliers; and
•
Government Authorities
Similarly, the identified causes of the design changes are:
•
Modifications to the original design;
•
Introduction of new works
•
Lack of coordination between design members;
•
Un-expected site conditions;
•
Alternatives construction methods;
•
Clients' financial difficulties;
•
Substitution of materials;
•
Conflict between contract documents;
•
Results of value engineering process;
•
Adoption of new technology;
•
Rectification of defective works;
•
Requirements for safety measures;
•
Changes to meet new governments regulations; and
•
Unclear contract clauses
The impacts of the design changes have also been identified firstly through the literature review and interviews with the professionals in the construction industry and then verified through the case studies and the questionnaire survey. The identified impacts of the design changes include:

258
•
Increase design fee;
•
Increase construction cost;
•
Delay design progress;
•
Delay construction progress;
•
Increase chances for material waste due to re-work operations;
•
Lead to loss of productivity and efficiency due to interruption and out of sequence works;
•
Lead to loss of motivation and momentum to re-do the work;
•
Increase chances for design mistakes;
•
Decrease quality of the works;
•
Increase chances for frustration, strain the relation and; and
•
Build-up bad atmosphere among concerned people
The following are the corrective actions and the preventive measures that have been identified from the result of the interviews with the professionals (Chapter 6,
Table 6.4) as well as from the identified causes of the design changes that presented in the literature review of this study and from the result of the questionnaire survey
(Chapter 6, Table 6.20).
•
Allocating sufficient time at the initial design stage to implement properly clients' ideas and to finalize the requirements of the proposed work;
•
Allocating sufficient time and funds at initial planning stage for feasibility studies, site investigations, detailing the existing site conditions and highlighting any site restrictions to avoid un-expected circumstances;
•
Involving specialized professionals at early planning stage for any extraordinary and/or unfamiliar works that may require special design arrangement;
•
Briefing and discussing with clients or their representatives in regular intervals the progress of the work and highlight any potential difficulties/concerns as early as possible;

259
•
Advising clients at early stages of any potential impacts that may result from each proposed change in particular on fee and time aiming to minimize the changes;
•
Engaging an experience co-ordinator or project director to represent client would ease the design process and transmission of information to the design members but may influence fee if not taken into consideration;
•
Setting up at the initial design stage a proper method of co-ordination and to be reviewed in regular basis to make any adjustment if deemed necessary;
•
A simple communication channel and better method for transmission of information would improve the efficiency of co-ordination and approval process;
•
A proper personnel evaluation and assigned responsibilities accordingly would assist assigning the right responsibility to the right personnel;
•
Providing clear and comprehensive design brief at early stage;
•
For each project, more effort is required to review the clauses of contract documents with reference to drawings in order to eliminate/reduce the inconsistency and deficiency between the documents;
•
An improvement to the working atmosphere and job satisfaction would increase the spirits and motivation of people and hence to the quality of the work produced; and
•
Centralizing responsibility for overseeing proper co-ordination between clients and design members and contractors
Four methods for assessing the fee of the structural design changes have been identified from the interviews and from the case studies that being in use in the
Sultanate of Oman. These methods are:
•
Man-Hours Method;
•
Percentage of Construction Cost Method;
•
Area Unit Rate Method; and

260
•
Lump Sum Method
Many limitations do exist in each of these methods (refer to Chapter 6, section 6.4.8.1). These limitations which considered disadvantages of each method are:
•
Not very accurate, not practical and not efficient;
•
Not easy to justify the amount of design changes;
•
Not easy to evaluate the fee of design changes;
•
Based on judgments, opinions and trusts;
•
Produce high fee of design change compared to the original fee; and
•
The implementations may lead to disputes on the claims
This method which has been called Percentage of Original Fee (POF) method was developed and presented in Chapter 7. It is based on a mathematical expression with coefficients that have been established for each main structural member. The
POF method was validated by panel of experts and found to be practical, suitable and effective. Hence, it was suggested by the panel of the expert who participated on the validation process that the method could be used as an alternative method to assess the fee of modifying the original structural design.
These guidelines have been constructed with reference to the recommendations for writing guidelines given by the American College of
Cardiology (ACC). The developed guidelines are based on the results of the literature review; the interviews; the case studies; and the questionnaire survey that all were part of this study. The guidelines have been verified by a panel of experts using Delphi techniques. These guidelines are:

261
•
The scopes of the engineering consultancy services to be provided shall be clearly defined in the consultancy contract documents;
•
Any existing information related to the proposed work shall be clearly defined in the consultancy contract documents and shall be available during the tender stage including the history of the site, pervious site investigations, existing structures, underground facilities, etc;
•
Any restrictions on the programme of the work, on the flow of the design information and any special design requirements shall be clearly defined in the consultancy contract design documents;
•
The consultancy scope of works shall be divided into separate sections according to the nature, similarity and complexity of each part of the project
(e.g. feasibility studies, similar buildings, roads, landscaping, building services, boundary walls, etc);
•
Each defined consultancy scope of work shall be divided into a preliminary design phase and a detailed design phase wherever applicable. Each phase shall be clearly defined in the consultancy contract document and shall have its own fee item(s);
•
A clear definition for what is to be considered design changes shall be included in the consultancy contract document;
•
Clear methods for assessing the fee of the design changes shall be included in the consultancy contract document at the tender stage; and
•
For large scale projects, especially fast track ones where the construction work is required to start before completion of the design, it is advisable to make a provision in the consultancy contract document at the tender stage to allocate certain design members specifically for design changes and to be paid on an agreed full/part time monthly basis for a particular duration. This

262 requirement shall be reviewed on a regular basis to make any adjustment if deemed necessary.
Guidelines for managing the claims of the design changes have also been established in the same manner as for the guidelines in item (E) above. These guidelines are expected to provide to the professionals in the construction industry the required justification for carrying out the design changes, to provide good documentation process as a back up for the claims and if implemented correctly minimise the chances for disputes arise from design changes as well as to avoid the lengthy process of evaluating the claims of the design changes. These guidelines are:
•
An initial agreement and formal instructions to carry out the design changes shall be provided and approved by the authorised persons;
•
Each claimed design change shall be given chronological reference number and date;
•
Each claimed design change shall be well documented in a pre-defined standard form. The form shall include the project name, the contract number, the variation reference number, date of issuing the variation, the name and the designation of the person who issued the change, brief details of the reasons for the changes and the nature and the extent of the changes;
•
Each claim shall be submitted along with all relevant drawings and/or calculations to the main contact person along with a covering letter (copied to all concerned people) confirming that the design will be revised per the received/verbal instruction;
•
Any possible impact on cost and program due to the design changes shall be highlighted to the client and agreed as early as possible;

263
•
A record shall be kept for the status of the completed design at the time of introducing the changes. This shall include all the drawings and calculations before modifying the design as a back up for the claims; and
•
The fee of each claimed design change shall be evaluated and settle down as early as possible. It is advisable not to accumulate un-settle claims to very late stages.
More is now known, as a result of this research, about the problems associated with design changes in particular their impacts on the construction industry. This research has identified the sources, causes and impacts of design changes on reinforced concrete buildings and has established corrective actions and preventive measures to minimise the avoidable ones. In addition, this research revealed the limitations of the existing methods for assessing the fee of design changes. Consequently, POF method has been developed in this research based on designing varies type and complexity of low rise RC buildings. The POF method has been verified by professionals working in the construction industry vide a questionnaire survey and found to be practical, suitable and effective. Set of guidelines for improving consultancy design documents with respect to design changes and another set of guidelines for managing their claims have been also developed. These guidelines have been validated by panel of experts using Delphi technique. The result of the validation process gives encouragement to recommend the guidelines for practical implementation.
As a result of the work undertaken for this research, it is suggested to extend the work further with reference to the following aspects:

264
•
More buildings' design are recommended to be carried out so that the pattern of the obtained coefficients for the POF method will be more consolidated such the way that they fall within normal distribution curve. In this case, standard deviations might be added to the coefficients;
•
It is recommended to extend the POF method to include other types of structural elements such as rafts and piled foundation, and shear walls. Such structures have not been dealt with in this part of the research;
•
It is also recommended to adopt the principle and the methodology of this research to develop similar coefficients for steel structure and composite buildings; and
•
Suggestion can be also made to adopt the principle and the methodology of this research to develop similar method based entirely on a structural design software programmes.

265
REFERENCES
Abd Majid, M. Z. and Mccafer R. (1997). Discussion of Assessment of Work
Performance of Maintenance Contractors in Saudi Arabia . Journal of
Management in Engineering, ASCE, 13(5): 91-92.
Abd Majid, M. Z. (1997). Non-Excusable Delays in Construction . PhD. Thesis.
Department of Civil and Building Engineering, Loughborough University
Loughborough, Leicestershire, UK.
Abou-zeid , A., Russell, J., Hanna, A. and Park, S. (1995). Data Flow Model for
Communications between Project Participants in Highway Bridge Project .
Canadian Journal of Civil Engineering, Ottawa, Canada, Vol. 22: 1224-1234.
Adler , M. and Ziglio, E. (1996 ). Gazing into the Oracle: The Delphi Method and
its Application to Social Policy and Public Health . Jessica Kingsley Publishers,
Bristol, London pp358-362
Al-Dubaisi , A. H. (2000). Change Orders in Construction Projects in Saudi
Arabia . MSc Thesis, King Fahd University of Petroleum & Minerals, Dhahran,
Saudi Arabia.
Al-Husaini, M. K. (2005). The Construction Sector: The Actual and Expectation .
Oman Chamber of Commerce and Industry, Sultanate of Oman
Akinsola , A. O., Potts, K. F., Ndekugri, I. and Harris, F. C. (1997). Identification
and Evaluation of Factors Influencing Variations on Building Projects .
International Journal of Project Management, 15(4): 263-267.
Al-Momani , A. H. (2000). Construction Delay: a Quantitative Analysis .
International Journal of project Management, Vol. 18: 51-59.
American Consulting Engineers Council, ACEC, (1982).
America n Society of Civil Engineers (1985). ASCE, New York, NY, USA.
America n Society of Civil Engineers, Manual and Reports on Engineering Practice
No. 45, (1988). Consulting Engineering: A Guide for the Engagement of
Engineering Services . ASCE, New York, NY, USA.
Anderson , S. D. and Tucker, R. L. (1994). Improving Project Management of
Design . Journal of Management Engineering, 10(4): pp35-44.
Anumba , C. J. (2000). Integrated Systems for Construction: Challenges for the
Millennium . Proceedings of the International Conference on Construction
Information Technology, Hong Kong, 8-92.

266
Arditi, D., Akan, G. T. and Gurdamar, S. (1985). Reasons for Delays in Public
Projects in Turkey . Construct Management Economics, Vol. 3: UK, 171-181.
Assaf, S. A., AlKhalil, M. and Al-Hazml, M. (1995). Causes of Delay in large
Building Construction Projects . Journal of Management in Engineering, ASCE,
Vol. 11, No. 2, pp45-50.
Association of Consulting Engineers Malaysia, (1998). Explanatory Guide to the
Use of BEM Forms and Scale of Fees . Kuala Lumpur, Malaysia.
Austin , S. A., Baldwin A. N., Li, B. and Waskett, P. (2000). Analytical Design
Planning Technique: A Dependency Structural Matrix Tool to Schedule the
Building Design Process . Construction Management Economics,
Vol. 18, pp173-182.
Austin , S. A., Baldwin A. N. and Steele, J. L. (2002). Improving Building Design through Integrated Planning and Control . Engineering, Construction and
Architectural Management, Vol. l.9, No. 3, pp 249-258.
Baldwin, A. N., Austin, S. A., Hassan, T. M. and Thorp, A. (1999). Modelling
Information Flow During Conceptual and Schematic Stages of Building Design .
Construction Management Economics, Vol. 17, pp155-167.
Baxendale, A. T. and Schofield, T. J. (1996). Planning and Progressing Project
Variations in Langford and Retik . The Organization and Management of
Construction: Shaping theory and practice, Vol. 2, E & FN SPON, UK.
Beech, B. (1999).
Go the Extra Mile-Use Delphi Technique . Journal of Nursing
Management, Vol. 7, pp 281-288.
Biech, E. (1999). Business of Consulting . Jossey-Bass/Pfeiffer, San Francisco,
CA, USA.
Blockley , D. I. (1986). Report of the Working Group on Error Control strategies:
Modelling Human Error in Structural Design and Construction . National Science
Foundation, Washington, D.C. USA.
Borcherding, J. D. (1976). Improving Productivity in Industrial Construction .
Journal of the construction Division, Proceeding of The American Society of Civil
Engineers, 102(C04): USA.
Bramble , B. B. and Cipollini, M. D. (1995). Resolution of Disputes to Avoid
Construction Claims . Transportation Research Board, National Research Council,
Washington D.C. USA.
Brockhaus , W. L. and Mickelsen, J. F. (1977). An Analysis of Prior Delphi
Applications and some Observations on its Future Applicability . Technical
Forcast. Social Change, Vol. 10, pp. 103-110

267
Bromilow , F.J. (1970). The Nature and Extend of Variations to Building Contracts .
The Building Economist, Vol. 9, No. 3, pp 93-118.
Bryman, A. (1996). Quantity and Quality in Social Research . Routledge, London,
pp201-212
BS, 8110, British Standard, Part 1: (1997). Structural use of Concrete, Code of
Practice for Design and Construction .
Bubshait, A. A., Al-Said, F. A. and Abolnour, M. M. (1998). Design Fee Versus
Design Deficiency . Journal of Architectural Engineering, ASCE, Vol. 4, No. 2 pp 44- 46.
Burati, J. L., Farrington, J. J. and Led, W. B. (1992). Causes of Quality
Deviation in Design and construction . Journal of Construction Engineering and
Management, ASCE, Vol. 118, No.1, pp 34-49.
Burgess, R. G. (1984). In the Field: an Introduction to Field Research . London,
Allen and Unwin, UK, pp 23-37
Caballero, A. A., Ahmed, S. M., Azhar, S. and Barcala, M. (2002). Development
of An Information Model to Enhance Integration and Coordination in the
Construction Projects . Florida International University, 10555 W. Flagler Street,
Miami, Florida 33174, USA.
Cariappa , A. (2000). The Effects of Contract Changes on Performance of
Construction Project s. MSc Thesis, The University of New Brunswick, Canada.
Chan , D. W. and Kumaraswamy, M. M. (1994) . A Survey of Time-Cost
Relationships in Hong Kong Construction Projects . Building Technology and
Management Journal, Vol. 20: 54-72.
Chan , D. W. and Kumaraswamy, M. M. (1995). Determinants of Construction
Duration . Construction Management and Economics, Vol. 13, No. 3, pp209-217.
Chan , D. W. and Kumaraswamy, M. M. (1996). An Evaluation of Construction
Time Performance in the Building Industry . Building and Environment,
Vol. 31, No. 6, pp569-578.
Chang, A. S. (2002). Reasons for Cost and Schedule Increase for Engineering
Design Projects .
Journal of Management in Engineering, ASCE, Vol. 18, No. 1,
pp 29-36.
Charles , T. J. and Andrew, M. A. (1990). Prediction of Cost-Overrun Rates .
Journal of Construction Engineering and Management, ASCE, Vol. 116, No.3,
pp 74 -81.
Choy , W. K. and Sidwell, A. C. (1991). Sources of Variations in Australian
Construction Contracts . The Building Economist, pp25-30.

268
Cockman , P., Evans, B. and Reynolds, P. (1992). Client-Centred Consulting .
Mcgraw-Hill Book Company Europe, England.
Cohen , S. (1982). Consulting Engineering Practice Manual . Mcgraw-Hill, Inc.
New York. USA.
Construction Engineering Council, (1993). The Procurement of Professional
Service s. Thomas Telford Services LTD, USA.
Construction Industry Institute (CII), Publication 6-10, (1990). The Impact of
Changes on Construction Cost and Schedule . The University of Texas at Austin,
Texas, USA.
Construction Industry Institute (CII), Special Publication 43-1, (1994). Project
Change Management . The University of Texas at Austin, Texas, USA.
Construction Industry Institute (CII), Publication 43-2, (1995). Quantitative Effects
of project Change . The University of Texas at Austin, Texas, USA.
Contractors' Directory (1991). Oman Chamber of Commerce and Industry.
Sultanate of Oman
Corotis, R., Fox, R. and Harris, J. (1981). Delphi Methods: Theory and Design
Load Application . Journal of the Structural Division, ASCE, Vol. 107, No. 6,
pp 95-105.
Cox, R. K. (1997). Managing Change orders and Claims . Journal of Management
in Engineering. January/February Issue, ASCE, 24-29.
Dalkey , N. C., Rourke, D. L., Lewis, R. and Sayder, D. (1972). Studies in The
Quality of Lif e. Lexington Books, Lexington, Mass, USA
Defence Construction Canada, DCC, Administration Manual , (DND, 1992).
pp 23-24.
Delbeeq , A. L. and Gustafson, D. H. (1975). Group Techniques for Programme
Planning: A Guide to Nominal Group and Delphi Process . Scott Foresman
Publishers, Glenview, ILL, USA.
Demkin , J. A. (2002). The Architect’s Handbook of Professional Practice . 13 th
Edition, John Wiley & Sons, Inc. USA.
Dickey , J. and Watts, T. (1978). Analytic Techniques in Urban and Regional
Planning . McGraw-Hill, New York. pp 87-94.
Dietz , T. (1987). Methods for Analysing data from Delphi Panels: Some Evidence
from a Forecasting Study . Technology Forecasting, Social Change, Vol. 31,
pp79-85.

269
Diekmann, J. E. and Nelson, M. P. (1992). Super Change: Expert System for
Analysis of Change Claims. Journal of Construction Engineering and
Management, ASCE, Vol. 111, No.1, pp 74-81.
Draft , R. L. (1986).
Organization Theory and Design . 2 nd
Edition, West Publishing
Co., St. Paul, Minnesota, USA, pp120-131.
Dreger , G. T. (1993). Design-Build Procurement: Strategies for Success .
Proceeding of CIB W-65 on Organization and Management of Construction: The
Way Forward, University of the West Indies, Port of Spain, Trinidad, Spain,
pp749-757.
Eddy, M. R. and Amlan, M., (2003). Modeling the Construction Management
Process to Support Situational Simulations. Journal of Computing in Civil
Engineering, ASCE, Vol. 17, No. 4, Pp273-280.
Eisenhardt, K. M. (1989). Building Theories from Case Study Research .
Academic Management Rev. Vol. 14, No.4, pp532-550.
Eldin, N. N. (1991). Management of Engineering/Design Phase . Journal of
Construction Engineering and Management, ASCE, Vol. 117, No.1, pp163-175.
Elinwa, A. U. and Buba, S. A. (1993). Construction Cost Factors in Nigeria .
Journal of Construction Engineering and Management, ASCE, Vol. 119, No.4 pp698-713.
Emmitt, S. (2001). Observing the Act of Specification . Design Studies, ASCE
Vol. 22, No.5, pp397-408.
Essex, R. J. (1996). Means of Avoiding and Resolving Disputes During
Construction . Tunnelling and Underground Space Technology, Vol. 11, pp27-31
Federal Construction Council (1983). Consulting Committee on Contract
Management, Technical Report No. 74. Managing Changes in the Construction
Process . National Academy Press. Washington D.C. USA.
Fellows , R and Liu, A. (1997). Research Methods for Construction . Blackwell
Science Ltd, UK.
Finke, M. R. (1998). A Better Way to estimate and Mitigate Disruption . Journal of
Construction Engineering and Management, ASCE, Vol. 124, No.6, pp490-497.
Fisk , E. R. (2000). Construction Project Administration.
6 th
Edition, Prentice Hall
Upper Saddle River, New Jersy, Columbus, Ohio. USA, pp456-475.
Frimpong, Y., Oluwoye, J. and Crawford, L. (2003). Causes of Delay and Cost
Overruns in Construction of Groundwater Projects in a Developing Countries;
Ghana as a Case Study . International journal of Project Management,
Vol. 21, pp321-326.

270
Ganeshan , R., Garrett, J. and Finger, S. (1994).
A Framework for Representing
Design Intent . Design Studies, Vol. 15, No.1, pp59-84.
Garrat , S. (1991). How to become a Consultant . Gower Publishing Company
Limited, U.K.
Gilbreath , R. D. (1992). Managing Construction Contracts . Second Edition, John
Wiley & Sons, Inc., New York, USA, 179-180.
Gil , E., Lucchesi, E., Tauber, G. and Onderdonk, D. (1983). Working with
Consultants . American Planning Association., Chicago, IL, USA.
Goldfisher , F. (1992). Modified Delphi: A Concept for New Product Forcasting .
Journal of Business Forecasting, Vol. 11, No. 4, pp 10-15
Goldstein , N. (1975). In the Delphi Techniques and Applications . Addison
Wesley, Reading, MA, USA, pp210-226.
Granovetter , M. (1985). Economic Action and Social Structure: The Problem of
Embeddedness . American Journal of Sociology, Vol. 9, No. 13, pp481-510.
Gunhan , S. and Arditi, D. (2005). International Expansion Decision for
Construction Companies . Journal of Construction Engineering and Management,
ASCE, Vol. 131, No. 8, pp928-937.
Hanna , A. S., Russell, J. S. and Gotzion, T. W. (1999). Impact of Change Orders
onLabour Efficiency for Mechanical Construction . Journal of Construction
Engineering and Management, ASCE, Vol. 125, No. 3, pp176-183.
Hashimoto , T. (1993). Problem on Design Production for Building Construction:
Sharing Roles and Information Among Designers and Builders .
Forum for
Japanese System, pp49-56.
Hartman , F. T. and Baldwin, A. (1995). Using Technology to Improve Delphi
Method . Journal of Computing in Civil Engineering, ASCE, Vol. 9, No. 4,
pp244-249.
Hess , G. R. and King, T. J. (2002). Planning Open Spaces for Wildlife I: Selecting
Focal Species using Delphi Survey Approach . Landscape and Urban Planning,
Vol. 58, USA, pp25-40
Hester , W. T., Kuprenas, J. A. and Chang, T. C. (1991). Construction Change
Orders: Their Magnitude and Impact . Construction Industry Institute, The
University of Texas at Austin, Texas, USA.
Hegazy , T., Zaneldin, E. and Grierson, D. (2001). Improving Design Coordination
for Building Projects. I: Information Model . Journal of Construction Engineering
and Management, ASCE, Vol. 127, No. 4, pp322-329.

271
Hew , K. P., Fisher, N., and Awbi, H. B. (2001). Toward an Integrated Set of
Design Tools Based on Common Data Format for Building and Services Design .
Automation in Construction, Vol. 10, pp459-476
Hibberd , P. R. (1982). Building Contract: Variations . MSc Thesis. The Victoria
University of Manchester, Manchester, UK
Hoon , L. P. (1979). Criteria for Selecting of Consultants with Special Reference to
Water Resources Development Study/Project . Seminar on Appointment of
Consultants, Kuala Lumpur, Malaysia.
Hurley, M. W. and Touran, A. (2002). Cost Structure and Profitability of Design
Services Industry . Journal of Management in Engineering, ASCE, Vol. 18, No. 4, pp167-172.
Ibbs , C. W. and Allen, W. E. (1995). Quantitative Impacts of Project Change .
Source Document 108, Construction Industry Institute, The University of Texas at
Austin, Texas, USA.
Ibbs , C. W. (1997). Quantitative Impact of Project Change: Size Issues . Journal of
Construction Engineering and Management, ASCE, Vol. 123, No. 3, pp308-311.
Jehn , K. A., and Shah, P. P. (1997). Interpersonal Relationships and Task
Performance: An Examination of Mediating Process in Friendship and
Acquaintance Group . Journal of Personality and Social Psychology,
Vol. 72, No. 4, pp775-790
Jergeas , G. F. and Hartman, F. T. (1994). Contractors’ Construction-Claims
Avoidance . Journal of Construction Engineering and Management, ASCE, Vol.
120 No. 3, pp553-561
Kartam, S. ( 1999). Generic Methodology for Analyzing Delay Claims . Journal
of Construction Engineering and Management, ASCE, Vol. 125, No.6,
pp409-419.
Kelvin, Y. (1996). Project Control: Cost/Schedule/Progress Management . Cost
Engineering, Vol. 38, UK
Kirby , J. G., Furry, D. A. and Hiks, D. K. (1988). Improvements in Design
Review Management . Journal of Construction Engineering and Management,
ASCE, Vol. 114, No.1, pp69-82
Kolarevic B. Schmitt, G. Hirschberg, U. Kurmann, D. and Johnson, B. (2000).
An Experiment in Design Collaboration . Automation in Construction,
Vol. 9. pp 73-81.
Kometa , S. T. Olomolaiye, P. O. and Harris, F. C. (1995). An Evaluation of
Clients' Needs and Responsibilities in the Construction Process . Engineering,
Construction and Architectural Management, Vol. 2, No. 1, pp57-76

272
Krishnamurthy , K. and Law, K. (1995). A Data Management Model for Design
Change control . Concurrent Engineering Research and Applications,
Vol. 3, No. 4, pp329-343
Kubr , M. (1993). How to Select and Use Consultants . International Labour Office,
Geneva.
Kumarasivam , K. (1979). Remuneration and Conditions of Contracts . Seminar
on Appointment of Consultants, Kuala Lumpur, Malaysia.
Kuprenas, J. A. (2003). Project Management Actions to Improve Design Phase
Cost Performance . Journal of Management in Engineering, ASCE,
Vol. 19, No. 1, pp 25-32
Latham, M. (1994). Constructing the Team . HMSO, London, UK.
Leonard , C. A. (1987) . The Effect of change orders on Productivity . Revay and
Associates, LTD., Montreal, Canada
Leonard , C. A. Fazio, P. and Moselhi, O. (1988 ). Construction Productivity:
Major Causes of Impact . AACE Transactions, New York, NY, ppD10.1-D10.7
Ling , Y. Y. Ofori, G. and Low, S. P. (1997). Developing a Model for Selection of
Consultants by Design-and-Build Contractors: A Pilot Study . Proceeding of 1 st
International Conference on Construction Industry Development: Build the Future
Together. National University of Singapore, Singapore, pp374-382.
Ling, Y. Y. and Tan, Y. W. (2001). Relevance of Network Factor in Selection of
Consultants . Journal of Professional Issues in Engineering Education and
Practice”. Vol. 127, No. 4, pp 190-195
Linston e, H. and Turoff, M. (1975). The Delphi Method: Techniques and
Applications . Addison Wesley, Reading, MA, pp.3-12
Loo , K. (1979). Remuneration and Conditions of Contracts . Seminar on
Appointment of Consultants, Kuala Lumpur, Malaysia.
Love , P. E., Holt, G. D., Shen, L.Y., Li, H. and Irani, Z. (2002). Using System
Dynamics to Better Understand Change and Rework in Construction Project
Management Systems . International Journal of project Management, Vol. 20 pp425-436
Lutz , J. D., Hancher, D. H. and East, E. W. (1990). Framework for Design
-Quality- Review Data-Base System . Journal of Management in Engineering,
ASCE, Vol. 6, No. 3, pp 296-311
Mason, J. (1996). Qualitative Researching . SAGE Publications Ltd, 6 Bonhill
Street, London, EC2A 4PU, UK, pp35-47

273
Mayer , R. R. (1980). The Design of social Policy Research . Printice-Hall, Inc.,
Englewood Cliffs, N.J. 07632, USA, pp8-17
McDermott , P. and Dodd, J. (1984). The Sources, Causes and Effects of
Variations on Building Contracts . Final Report of a Study Supported by Science
and Engineering Research Council, Construction Study Unit, Brunel University,
Uxbridge, UK.
Meyers , J. (1994). Changes Resulting from Delays . Construction Change Order
Claims, John Wiley and Sons, Inc., Somerset, NJ, USA, pp213-220.
Mendenhall , W., Reimuth, J. and Beaver, R. (1993). Statistics for management
and Economics . 7 th
edition, Duxbury Press. Belmont, CA, USA
Merrill, W. E. (1982). Air Force Construction Contract Disputes . Report No.
LSSR 88-82, U.S Department of Commerce, USA
Mitchell, J. C. and Eschenbach, T. G. (1999). Compensation of Consulting
Engineers: Legalities and Realitie s. Journal of Management in Engineering,
ASCE, Vol. 15, No. 1, pp 66-73
Mitchell , V. W. (1991). The Delphi Technique: An Exposition and Application.
Technical Analysis Strategy Management, Vol. 3, No.4, pp333-358
Mobbs , G. N. (1989). The Influence of Global investment or the decline of the
British Commercial imperialism . Public Lecture Series in Estate Management,
Collage of Estate Management, Reading, UK
Mokhtar , A. H. (1998a). An Information Model for Managing design Changes in a
Collaborative Multi-Disciplinary Design Environment . PhD Thesis, Concordia
University, Montreal, Quebec, Canada.
Mokhtar, A., Bedard, C. and Fazio, P. (1998b). Information Model for Managing
Changes in a Collaborative Environment . Journal of Computing in Civil
Engineering, ASCE, Vol. 12, No. 2, pp82-92.
Mokhtar , A. H. M. (2002). Coordination and Customizing Design Information
through the Internet . Engineering Construction and Architectural Management,
Vol. 9, No. 3 pp222-231
Moony , R. (1995). A call for Quality in Engineering Business . Journal of
Computing in Civil Engineering, ASCE, Vol. 9, No. 3, pp191-193
Morgan , D. L. (1998). The Focus Group Guidebook . Focus Group Kit 1, Sage,
Beverly Hills, CA.
Moselhi , O., Leonard, C. and Fazio, P. (1991). Impact of Change Orders on
Construction Productivity . Canadian Journal of Civil Engineering, Vol. 18, No.3,
pp 481-492.

274
Mosley , W. H., Bungey, J. H. and Hulse, R. (1999). Reinforced Concrete Design .
5 th
Edition, Palgrave, New York, USA, pp220-241
Newcombe , R., Langford, D. and Fellows, R. (1996). The Sources, Causes and
Effects of Variations on Building Construction Study Unit . Brunel University,
Uxbridge, UK
Nordin , B. (1979). Procedure and Criteria for Selecting and Appointment of
Consultants . Seminar on Appointment of Consultants, Kuala Lumpur, Malaysia.
Ogunlana, S. O., Promkuntong, K. and Jearkjirm, V. (1996 ). Construction Delays
in a Fast-Growing Economy: Comparing Thailand with other Economies.
International Journal of project Management, Vol. 14, No. 1, pp37-45
Okpala , D. C. and Aniekwu, A. N. (1988). Causes of High Costs of Construction
Projects in Nigeria . Journal of Construction Engineering, Vol. 114 No. 2,
pp233-244
Oman Chamber of Commerce and Industry (2005). Sultanate of Oman
Patton , M. Q. (1987). How to Use Qualitative Methods in Evauation . SAGE
Publications Ltd, 6 Bonhill Street, London, EC2A 4PU, UK, pp7-22
Peltonen , H., Mannisto, T., Alho, K. and Sulonen, R. (1993). An Engineering
Document Management System . Proceeding of American Society of Mechanical
Engineers, Winter Annual Meeting, New York, USA
Pena-Mora , F., Sriram, D. and Logcher, R. (1995). Design Rationale for
Computer- Supported Conflict Mitigation . Journal of Computing in Civil
Engineering, ASCE, Vol. 9, No. 1, pp57-72
Pocock , J.B., Liu, L. Y. and Kim, M. K. (1997). Impact of Management Approach
on Project Interaction and Performance . Journal of Construction Engineering
and Management, ASCE, Vol. 123, No. 4, pp411-418.
Ramanath , A. (1979). Criteria for Selecting of Consultants and Position of Foreign
Consultants . Seminar on Appointment of Consultants, Kuala Lumpur, Malaysia.
Ray , S. S. (1995). Reinforced Concrete Analysis and design . First edition, Black
well Science Ltd, Australia, pp215-292
Reynolds , C. E. and Steedman, J. C. (1988). Reinforced Concrete Designer's
Handbook . 10 th
Edition, Rupa Paperback, India, pp 206-216
Rezgui , Y. and Debras, P. (1995). An Integrated Approach for a Model Based
Document Production and Management . Electronic Journal of Information
Technology in Construction, www/itcom.org
Robinson , J. B. L. (1991). Delphi Technology for Economic Impact Assessment .
Journal of Transportation Engineering, Vol. 117, No. 3

275
Sinha , S. N. (2002). Reinforced Concrete Design . Second Edition, Tata McGraw
-Hill Publishing Company Limited, New Delhi, India, pp301-391
Smith , M. A. (1996). Construction Insurance, Bonding & Risk Management .
McGraw-Hill, New York, USA
Soh, C. K. and Wang, Z. (2000). Parametric Coordinator for Engineering
Design . Journal of Computing in Civil Engineering, ASCE, Vol. 14, No. 4,
pp233-240
Southgate , T. (1988). Cost Planning – a New Approach . Chartered Quantity
Surveyors, Journal of the RICS, Vol. 9, No. 10, pp32-38.
Spooner , D. and Hardwick, M. (1993). Using Persistent Object Technology to
Support Concurrent Engineering System . Concurrent Engineering: Methodology
and Applications, P. Gu and A. Kusiak, eds., Elsevier Science,
Amsterdam, pp205-234
Ssegawa , J. K., Mfolwe K. M., Makuke, B. and Kutua, B. (2003). Construction
Variations: A Scourge or a Necessity ?. Civil Engineering Department,
University of Botswana, Gaborone, Botswana, pp81-90.
Stanley , C. M. (1982). The Consulting Engineer . Second Edition, John Wiley &
Sons, Inc. USA
Statistical Year Book (August 2002). Ministry of National Economy, Sultanate of
Oman
Statistical Year Book (August 2003). Ministry of National Economy, Sultanate of
Oman
Statistical Year Book (October 2004). Ministry of National Economy, Sultanate of
Oman
Sullivan , A. and Harris, F. C. (1986). Delays on Large Construction Projects .
International Journal of Operation Prod. Management, Vol. 6, No. 1, pp25-33
Teicholz, P. and Fisher, M. (1994) . Strategy for Computer Integrated Construction
Technology . Journal of Construction Engineering and Management, ASCE, Vol.
120, No. 1, pp117-131
The Institute of Civil Engineers , (1996 ). Civil Engineering Procedure, Fifth
Edition, Thomas Telford, UK, pp49-61
The Standard Form of Agreement and Conditions of Engagement for Consultancy
Services for Building and Civil Engineering works, Sultanate of Oman (1987)
Thomas , H. R. and Napolitan, C. L. (1995). Quantitative Effects of Construction
Changes on Labor Productivity . Journal of Construction Engineering and
Management, ASCE, Vol. 121, No. 3, pp290-296

276
Thomas , H. R., Korte, Q. C., Sanvido, V. E. and Parfitt, M. K. (1999). Conceptual
Model or Measuring Productivity of Design and Engineering . Journal of
Architectural Engineering, ASCE, Vol. 5, No. 1, pp1-7.
Trickey, G. and Hackett, M. (2001). The Presentation and Settlement of
Contractor's Claims.
Spon Press, London, UK, pp311-320
Turner , D. (1984). Standard Contracts for Building . George Godwin, England
Valkenburg , R. C. (1998). Shared Understanding as a Condition for Team Design.
Automation in Construction, Vol. 7, pp111-121.
Vries , B. and Somers, L. (1995). Message Exchange in the building Industry .
Automation in Construction, Vol. 4, pp91-100
Williams , A. P. O. and Sally, W. (1994). Competitive Consultant . The Macmillan
Press LTD. UK.
Williams , P. L. and Webb, C. (1994). The Delphi Technique: A Methodological
Discussion . Joutnal of Advanced Nursing, Vol. 19, pp180-186.
Wilson , R. L. (1982). prevention and Resolution of Construction Claims . Journal
of Construction Division Vol. 108, No.CO3 pp390-405
Yeung , I. Y. and Tung, R. L. (1996). Achieving Business Success in Confucian
Society: The Important of Connections . Organizational Dyn., Vol. 25, No., 2,
pp 54-65
Yogeswaran , K. (1998). Sources, Causes and Minimisation of Contractual Claims
in Civil Engineering Projects in Hong Kong . PhD Thesis, The University of
Hong Kong Hong Kong.
Zaki, M. K. and James, E. D. (1987). Concurrent Delays in Construction Projects .
Journal of Construction Engineering and Management, ASCE, Vol. 113, No. 4,
pp120-126
Zaneldin , E., Hegazy, T. and Grierson, D. (2001). Improving Design Coordination
for Building Projects. II: A Collaborative System . Journal of Construction
Engineering and Management, ASCE, Vol. 127, No. 4, p330-336.
Zeitoun , A. and Oberlender, G. (1993). Early Warning Signs of Project Changes .
Oklahoma State University, CII Source Document No. 91. USA
Zhang , X. (2004). Concessionaire Selection: Methods and Criteria . Journal of
Construction Engineering and Management, ASCE, Vol. 130, No. 2, pp235-244

277
EXTRACT FROM STANDARD FORM OF AGREEMENT AND
CONDITIONS FOR CONSULTANCY SERVICES FOR BUILDING AND
CIVIL ENGINEERING WORKS (1987)

278

279

280

281

282

283

QUESTIONNAIRE SURVEY (SECOND STAGE)
284

285
Universiti Technologi Malaysia
Construction Technology and Management Centre
Faculty of Civil Engineering
Date: …………………….
Sub. Research on “Assessment of the Structural Design
Amer Al-Harthy
P.O. Box 411
Postal Code 413, Ibra
Sultanate of Oman
Telephone No.
9217037
Fax No. 736788
Dear Sir
I am a PhD research student attached to the Faculty of Civil Engineering of the
Universiti Technologi Malaysia and carrying out research on the abovementioned subject in Sultanate of Oman.
The research is aimed at identifying equitable ways to minimize the avoidable design changes on RCC buildings and to develop better method to assess the consultant engineers’ fees for re-design the structures. It relies on realistic and extensive feedback from the construction industry in order to achieve meaningful results that would in turn benefit the industry. Accordingly, I seek your kind assistance in completing and returning the attached questionnaire along with any comments and/or extra information that are necessary in your opinion to the study either by fax or call me to pick it up.
The information supplied will be kept strictly confidential and used for statistical analysis along with data from other responses. If any item is unclear, please contact me at my above phone number.
I thank you for your attention and look forward to a very early response, preferably before 21 February 2004.
Yours sincerely
Amer Al-Harthy

286
General Information
Organization Name
(Optional):_______________________________________________________
________________________________________________________________
Type of Organization Client/Owner/Employer 1
(Please circle the appropriate description) Consultant 2
Contractor 3
Others 4
If others please specify ______________________________
Contact Name (Optional):_______________________________________________
Contact Position (Optional):_____________________________________________
Contact Phone (Optional):________________Contact Fax (Optional):____________
Number of years you have been in the industry: _____________Years.
Definition of Design Changes
Design changes, whether during design or construction, is simply defined as any addition, omission or modification to the original scope of work after the contract has been signed.

287
1. Causes of Design Changes Due to Consultants Clients
Please rate the following causes of design changes due to clients based on your experience using the scale from 1 to 5 where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
Common Cause(s) Rating a) Additions of new works/scopes (not part of original scope) b) Omission of works/scopes (reduction on original scopes) c) Modifications to the original design (changes within the original
scope) d) Not clear initial design brief (e.g. the extent of the scope,
requirements, details etc.) e) Desire to use alternative material/new technology (may require
different details and coordination with suppliers) f) Desire to use better specification (e.g. to extend the life of the structure or for better performance etc., may require different design detail) g) Insufficient background of proposed site (e.g. possibility of underground facilities, previous structures, previous site condition etc.)
Others (If any please state and rate) h) ____________________________________________________
___________________________________________________ i) ____________________________________________________
____________________________________________________ j) ____________________________________________________
____________________________________________________

288
2. Causes of Design Changes Due to Consultants
Please rate the following causes of design changes due to consultants based on your experience using the scale from 1 to 5 where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
Common Cause(s) a) Improper design /part of design improvement (e.g. to rectify design
mistakes, to adopt better detailing, to simplify the design for easy
construction etc.)
Rating b) Inconsistent information in drawings (e.g. structural detail is not
matching architectural detail etc.) c) Discrepancy between contracts documents (e.g.
drawings/specification, Bill of Quantities etc.) d) Lack of/insufficient geotechnical investigation or wrong
interpretation of the findings (e.g. un-expected rock layers, loose
soil, high water table etc.) e) Insufficient detail of existing site condition (e.g. clashes with underground facilities, clashes with adjacent structures, flooding condition at site, etc.)
Others (If any please state and rate) f) ______________________________________________________
_____________________________________________________ g) ______________________________________________________
______________________________________________________ h) _____________________________________________________
______________________________________________________

289
3. Causes of Design Changes Due to Contractors
Please rate the following causes of design changes due to contractors based on your experience using the scale from 1 to 5 where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
Common Cause(s) Rating a) To use available material b) To use alternative construction methods to save time c) To use alternative construction methods to save money d) To rectify construction mistakes e) To improve the quality of works at site
Others (If any please state and rate) f)___________________________________________________ g)__________________________________________________

290
4. Sources of Design Changes
Please rate the following sources of design changes based on your experience using the scale from 1 to 5 where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
a) Clients b) Consultants Engineers c) Contractors d) Design Members (e.g. Interior Designers, Acoustic Engineers etc.)
Others (If any please state and rate) e)_____________________________________________________ f)_____________________________________________________

291
5. Impacts of Design Changes
Please rate the following impacts of design changes based on your experience using the scale from 1 to 5 where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
Common Impact(s) Rating a) Increase design cost b) Increase construction cost c) Delay design progress d) Delay construction progress e) Increase chances for material waste due to re-work operations f) Lead to loss of productivity and efficiency due to interruption and
out of sequence works g) Lead to loss of motivation and momentum to re-do the work h) Increase chances for design mistakes i) Decrease quality of works j) Increase chances for frustration, strain the relation and build-up bad
atmosphere among concerned people
Others (If any please state and rate) k) ___________________________________________________
___________________________________________________ l) ___________________________________________________
__________________________________________________ m) __________________________________________________
___________________________________________________

292
6. Corrective Actions and Preventive Measures to Minimize the
Avoidable Design Changes.
Please rate the response that best describe an appropriate corrective actions
and/or preventive measures that could minimize the design changes based on your experience using the scale from 1 to 5 where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
Rating Corrective Action(s) and/or Preventive Measure(s) a) Allocating sufficient time at the initial design stage to implement properly clients' ideas and to finalize the requirements of the proposed work. b) Allocating sufficient time and funds at initial planning stage for feasibility studies, site investigations, detailing the existing site conditions and highlighting any site restrictions to avoid un-
expected circumstances. c) Involving specialized professionals at early planning stage for any extraordinary and/or unfamiliar works that may require special
design arrangement. d) Briefing and discussing with clients or their representatives in
regular intervals the progress of the work and highlight any
potential difficulties or concerns as early as possible. e) Advising clients at early stages of any potential impacts that may
result from each proposed change in particular on cost and time
aiming to minimize the changes. f) Engaging an experience coordinator/project director to represent client would ease the design process and transmission of information to the design members but may influence cost if not taken into consideration g) Setting up at the initial design stage a proper method of
coordination and to be reviewed in regular basis to make any
adjustment if deemed necessary. h) A simple communication channel and better method for
transmission of information would improve the efficiency of coordination and
approval process. i) A proper personnel evaluation and assigned responsibilities accordingly would assist assigning the right responsibility to the right personnel. j) Providing clear and comprehensive design brief at early stage

293
6. Corrective Actions and Preventive Measures to Minimize the
Avoidable Design Changes (Continue).
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
Corrective Action(s) and/or Preventive Measure(s) k) For each project, more effort is required to review the clauses of contract documents with reference to drawings in order to eliminate/reduce the inconsistency and deficiency between the documents. l) An improvement to the working atmosphere and job satisfaction
would increase the spirits and motivation of people and hence to the quality of the work produced.
Rating m) Centralizing responsibility for overseeing proper coordination
between clients and design members and contractors
Others (If any please state and rate) n) ____________________________________________________
____________________________________________________ o) ____________________________________________________
___________________________________________________ p) ___________________________________________________
____________________________________________________

294
7. Existing Methods for Assessing the Cost of Design Changes
The existing methods for assessing the cost of design changes have been identified to be Man-Hours Method, Percentage of Construction Cost
Method, Area Unit Rate Method and Lump-Sum Method
Please select your preference to use the existing methods for assessing
the cost of design changes based on your experience using the preference numbers listed below .If you are aware of other methods please state them with appropriate preference number where:
Preference No. 1 .
First Choice; 2. Second Choice; 3. Third Choice: 4. Forth choice: etc
Method
Preference no.
a) Man-Hours Method b) Percentage of Construction Cost Method c) Area Unit Rate Method d) Lump Sum Method
Others (If any please state and rate) e)_________________________________________________ f)_________________________________________________

295
8. Limitations of the Existing Methods
Please state your opinion on the following possible limitations of the
existing methods of assessing the cost of design changes based on your experience using the scale from 1 to 5 by inserting rate number on appropriate box(es) that best match the possible limitation(s) to each method where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree; 5.
Strongly Agree
Possible Limitation(s)
Man-
Hours
Methods
Percentage of
Area Unit
Construction
Cost
Rate
Lump-
Sum
Not very accurate, not practical and not efficient
Not easy to justify the amount of design changes
Not easy to evaluate the cost of design changes
Based on judgments, opinions and trusts
Produce high cost of design change compared to the original cost
The implementations may lead to disputes on the claims
Others (If any please state and rate)
Thank you for responding
Do you need a copy of the questionnaire result? 1. Yes 2. No
If yes; kindly fill your contact detail in the first page

296

8
7
6
5
9
BUILDING REFERENCE 1A
A B C D E F G H J K L
297
K
2
1
4
3
K
GROUND FLOOR PLAN

BUILDING REFERENCE 1A
FRONT ELEVATION
298
LEFT SIDE ELEVATION

BUILDING REFERENCE 1B
A B C D E F G H J K L M N P
299
13
12
11
10
9
5
4
8
7
6
K
3
2
1
GROUND FLOOR PLAN
K

BUILDING REFERENCE 1B
300
FRONT ELEVATION
LEFT SIDE ELEVATION

5
2
1
4
3
BUILDING REFERENCE 1C
A B C D E F G H J
301
12
11
7
6
10
9
8
X X
GROUND FLOOR PLAN

BUILDING REFERENCE 1C
302
FRONT ELEVATION
RIGHT SIDE ELEVATION

BUILDING REFERENCE 2A
303
GROUND FLOOR PLAN

BUILDING REFERENCE 2A
304
FRONT ELEVATION
LEFT SIDE ELEVATION

BUILDING REFERENCE 2B
305
GROUND FLOOR PLAN

BUILDING REFERENCE 2B
306
FRONT ELEVATION
RIGHT SIDE ELEVATION

BUILDING REFERENCE 2C
A B C D E F G H
307
1
2
3
3
B
4
5
6
7
8
9
10
R
GROUND FLOOR PLAN
R

BUILDING REFERENCE 2C
FRONT ELEVATION
308
RIGHT SIDE ELEVATION

6
7
8
9
10
R
1
2
3
4
5
BUILDING REFERENCE 3A
A B C C
1
D E F G H J
309
R
GROUND FLOOR PLAN

BUILDING REFERENCE 3A
310
FRONT ELEVATION
RIGHT SIDE ELEVATION

BUILDING REFERENCE 3B
311
GROUND FLOOR PLAN

BUILDING REFERENCE 3B
FRONT ELEVATION
312
LEFT SIDE ELEVATION

BUILDING REFERENCE 3C
E F
A B C D G H
J N S
K L M P Q R T U V
313
14
13
7
6
5
4
3
2
12
11
10
9
8
K
1
GROUND FLOOR PLAN
K

BUILDING REFERENCE 3C
FRONT ELEVATION
314
LEFT SIDE ELEVATION

12
13
14
15
7
8
9
10
11
3
4
5
6
BUILDING REFERENCE 4A
1
2
K
17
18
19
K
315
24
A B C D E F H J K
G L
M P Q R S U V W
N T
GROUND FLOOR PLAN
X Y

BUILDING REFERENCE 4A
FRONT ELEVATION
316
LEFT SIDE ELEVATION

BUILDING REFERENCE 4B
317
GROUND FLOOR PLAN

BUILDING REFERENCE 4B
318
FRONT ELEVATION
LEFT SIDE ELEVATION

BUILDING REFERENCE 4C
319
GROUND FLOOR PLAN

BUILDING REFERENCE 4C
320
FRONT ELEVATION
RIGHT SIDE ELEVATION

APPENDIX D
TYPICAL STRUCTURAL DESIGN AND DETAIL
321

BUILDING REFERENCE 2B
322
FOUNDATION & COLUMNS PLAN

BUILDING REFERENCE 2B
323
PLINTH BEAMS PLAN

BUILDING REFERENCE 2B
324
GROUND FLOOR ROOF SLABS/BEAMS PLAN

BUILDING REFERENCE 2B
325
FIRST FLOOR ROOF SLABS/BEAMS PLAN

BUILDING REFERENCE 2B
326
FOOTINGS & COLUMNS DETAILS

BUILDING REFERENCE 2B
327
DETAILS OF PLINTH BEAMS & GROUND FLOOR ROOF SLABS/BEAMS

BUILDING REFERENCE 2B
328
STAIR CASE STRUCTURAL DETAILS

BUILDING REFERENCE 2B
329
Front arch detail
SECTIONS STRUCTURAL DETAILS

APPENDIX E
QUESTIONNAIRE FOR
VALIDATING THE POF METHOD
330

331
Amer bin Salim Al-Harthy
P.O. Box 411
Postal Code 413, Ibra
Sultanate of Oman
Telephone No. 99217037
Fax No. 24736788
Universiti Technologi Malaysia
Construction Technology and Management Centre
Faculty of Civil Engineering
Date: …………………..
Sub. Research on "Assessment of the Structural
Design Changes on RCC Buildings"
Dear Sir;
I am a PhD research student attached to the Faculty of Civil Engineering at the Universiti Technologi Malaysia and carrying out research work on the above-mentioned subject in the Sultanate of Oman.
As part of this study, a method called Percentage of Original Fee (POF) for assessing the consultancy fee a result of structural design changes has been developed and is attached along with a questionnaire. The aim of the questionnaire is to obtain professional opinions on the suitability of the developed method, its effectiveness and its practicality.
In order to achieve meaningful results that would in turn benefit the industry, I seek your kind assistance in completing and returning the questionnaire along with any comments and/or extra information that may in your opinion enhance the result of this research work. The supplied information will be kept strictly confidential and used only for this study. If any item is unclear, kindly contact me at the above phone number.
Your attention and assistance in this regard are greatly appreciated and I look forward to your early reply, preferably before Monday 11 April 2005.
Yours Sincerely
Amer Al-Harthy

332
1. Introduction
Existing literature and the findings of this research work indicated that design changes are common almost in all construction projects across the globe. Design variation is defined as any addition, omission or modification to the original scope of work after the contract has been signed or modifications to the existing design. These changes are caused by many reasons in which the clients are the most common source. Design changes could be minors related to design development which have no or relatively low cost and time effect but could be majors related to new ideas or changing the principle of the original design which, in turn, required re-planning and re-designing that might leads to major cost and time effects. The assessment of the consultancy extra cost associated with the modification of the structural design on
RCC buildings stands to date as one of the problems in the construction industry that needs to be addressed so that the most likely disputes in this regard might be at least minimized if not totally eliminated. Hence, one of the main objectives of this study is to come up with a practical and more effective method to assess the cost of the structural design changes that has not been given yet the required level of attention.
2. Methodology of the Work
To achieve the above objective, twelve different types of low rise concrete buildings ranging from one floor to four floors were carefully selected, designed and drafted structurally aiming to generate the data that is needed for this research work. Times, in minutes, have been recorded for designing and drafting each structural activity. As examples, the time requires for designing the footings, columns, beams, roofs, etc, has been established for each building. Having the time record for designing various structural members and elements, the percentage of the time for each structural group has been established and hence has lead to a form of quantifying the amount of the structural design for each element percentage wise which then correlated to the amount of the design changes proportionally and hence to the original design cost.
This methodology has been extracted from the result of the case studies, the interviews with the professionals working in the construction industry in the
Sultanate of Oman as well as from the result of the questionnaire that all have been carried out at the earlier stage of this research work. The result of these initial investigation revealed that the most common method that is in use by the consultants

333 to claim extra cost due to design changes in the Sultanate of Oman is the man-hours method. There are many examples in the case studies where the consultants have submitted the man-hours to their clients that have been claimed to be the actual manhours spent to execute the changes. The man-hours in these cases are the total hours for each claimed change and cannot be assessed by clients if the man-hours are not totally accepted. Similar approach have been adopted for this research work accept that more detailed break down of the timing is maintained in an intention to approximate the time that most likely be required to design the structural members so that an assessment to the claimed design changes can be carried out. For the purpose of the data collection for this research work, two Consultants along with the
Researcher have carried out the structural design and drafting of the buildings so that better data representative were obtained.
3. The Principle of the Adopted Structural Design
An intensive discussion with the professionals along with various references of the commonly used contract documents in the Sultanate of Omen have been taken place at the early stage of this part of the research to identify the mostly used methods of the structural design, the level of detailing and the common contracts’ design clauses.
Similar approach to the finding of this investigation has been followed so that the adopted method of the design matches with the existing practice in the construction industry. It has been revealed from this exploration phase that the majority of the consultants are designing the reinforced concrete buildings either manually or by a combination of manual design along with computer Software. Most of the consultants have developed their own spreadsheets in which Microsoft Excel is the dominated one. Nevertheless, only certain structural elements such as columns, beams and/or, in some instances, footings are carried out by computer Software. Due to this, and to get better consistent data, the proposed POF method is based on manual structural design calculations. However, some of the buildings have been designed by Staad Pro software and used for comparison only.

334
4. Proposed POF Method for Assessing the Cost of the Structural Design
Changes
The result of the data analysis that have been achieved for the twelve number of buildings ranging from one floor to four floors has been used to suggest a method for assessing the cost of the structural design changes when they occur. The proposed
POF method is based on the mean average percentages of time that have been estimated for each type of buildings. In addition, a proposal has also made to consider two stages of design. These are preliminary design stage and detailed design stage. The rationale behind splitting the design to these stages is being that it is likely to have design changes due to various reasons at early stage of the design as well as at later time and hence the amount of the changes can be assessed at the time when they occur. Table 1 and Table 2 below show the obtained mean average percentages of time for the preliminary and detailed structural design respectively. It is suggested to use these percentages as coefficients for better matching with the forthcoming proposed mathematical expression.
Table 1: Percentage of Time for Preliminary Structural Design and Drafting (One
Floor to Four Floors Buildings)
STRUCTURAL MEMBERS
One
Floor
Build.
Coeff.
(% of
Time)
Two
Floors
Build.
Coeff.
(% of
Time)
Three
Floors
Build.
Coeff.
(% of
Time)
Four
Floors
Build.
Coeff.
(% of
Time)
1. Columns' locations and sizing
2. Plinth beams' locations and sizing
3. Floor beams’ locations and sizing
4. Slabs' locations and sizing
5. Footings' locations and sizing
7
3
7
3
7
2
7
2
6. Stair preliminary design
7. Arches preliminary design
11 9 8 7
8
8. Sections preliminary design 10 8 7 7
Notes: 1. The above coefficients are only valid for RCC buildings
2. No allowances have been made for shear walls, rafts and piles footings

335
Table 2: Percentage of Time for Detailed Structural Design and Drafting (One Floor to Four Floors Buildings)
STRUCTURAL MEMBERS
One
Floor
Build.
Coeff.
(% of
Time)
Two
Floors
Build.
Coeff.
(% of
Time)
Three
Floors
Build.
Coeff.
(% of
Time)
Four
Floors
Build.
Coeff.
(% of
Time)
1. Columns' detailed design
2. Plinth beams' detailed design
3. Floor beams’ detailed design
4. Roof slabs' detail detailed design
5. Footings' detailed design 6
6 7
9
6. Stair case detailed design
7. Arches' detailed design
7
8
6
6
5
6
6
6
8. Sections' detailed design 5 5 4 5
Notes: 1. The above coefficients are only valid for RCC buildings
2. No allowances have been made for shear walls, rafts and piles footings
Fee of the Structural Design Changes
=
⎡
⎢⎣ Coeff .
X
NMSM
TNSM
⎤
⎥⎦ X OCC
Where:
Coeff : To be obtained from Table 1 (for preliminary structural design) or from
Table 2 (for detailed structural design) wherever applicable
NMSM : Number of the Modified Structural Members corresponding to TNSM
TNSM : Total Number of the structural Members before the changes which can
be estimated as follow:
For columns : Total number of columns at footings’ level before the
changes
For beams : Total number of spans between beams’ supports before
the changes
For slabs : Total number of slabs’ panels before the changes
For Footings : Total number of columns at footings’ level before the
changes (Not total footings)
For stairs, arches & sections : Total number of each before the changes
OCC : Original Contract Cost, (either preliminary or detailed design cost)

336
Example: The detailed structural design of two floors building has been modified
The original structural design before the modification consists of 32 columns, 48 plinth beams, 94 floor beams, 28 roof slabs' panels, isolated & combined footings, 1 stair, 3 arches and 3 sections. The modification has only affected 10 columns, 12 plinth beams, 25 floor beams, 4 slabs' panels and the footings for the 10 columns. No modifications were carried out for the stair, the arches and the sections. The original contract consultancy structural design cost OR 28,000 for preliminary structural design and OR 24,000 for detailed structural design. Thus, the cost of modifying the original structural design based on the above equation is:
Cost of the preliminary structural design changes =
[
12
100
X
X
10
32
+
7
100
X
X
12
48
+
23
100
X
X
25
94
+
3
100
X
X
4
28
+
28
100
X
X
10
32
] X 28 , 000
=
5 , 703
Cost of the detailed structural design changes =
[
32
100
X
X
10
32
+
10
100
X
X
12
48
+
22
100
X
X
25
94
+
10
100
X
X
4
28
+
9
100
X
X
10
32
] X 24 , 000
=
5 , 079
Total cost of the structural design changes = OR. 10,782

337
General Information
Organization Name :____________________________________________
Contact Name :________________________________________________
Contact Position :______________________________________________
Contact Phone :__________________________
Number of years you have been in the industry: _____________Years.
Please rate and comment on the following based on your experience and opinion using the scale from 1 to 5 where:
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree;
5. Strongly Agree
Observations Rating
1) The principal of the POF method is acceptable
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
2) The adopted methodology for the POF method is acceptable
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
3) The proposed coefficients in Tables 1 and Table 2 are reasonable
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------

338
Continue ………..
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree;
5. Strongly Agree
Observations Rating
4) The definitions of the parameters used in the mathematical expression are acceptable
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
5) The POF method is practical
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
6) The POF method is suitable for assessing the consultancy cost of the structural design changes
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
7) The POF method is only valid for limited type of projects
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
8) There is no confidence yet in the POF method
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------

339
Continue ………..
Rates : 1. Disagree ; 2. Slightly Agree; 3. Agree in Average; 4.Mostly Agree;
5. Strongly Agree
Observations Rating
9) The method could be better if it is based on computer software rather than manual calculations
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
10) In summary, the method is acceptable
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
11) The POF method can be suggested to be in the contract documents for the structural design changes
Comments : ----------------------------------------------------------------------
----------------------------------------------------------------------
----------------------------------------------------------------------
End of the questionnaire
Thanks for your reply. Your time and assistant are greatly appreciated

340

341
I am a PhD research student attached to the Faculty of Civil Engineering at the University Technology Malaysia and carrying out research work on the above-mentioned subject in the Sultanate of Oman.
As part of this study, guidelines for improving the consultancy design documents with respect to design changes have been developed and are attached herewith. The aim of this stage of the research is to validate the developed guidelines in term of their suitability, practicality and effectiveness. The validation process will be carried out in three rounds and with seven professionals including you. The attached questionnaire is the first round and is intended to construct a set of guidelines to manage the contractual issues associated with the design changes that are thought to be useful to the professionals in the construction industry. The second round of this validation process will be to determine the significance level of each guideline obtained in round one and to eliminate inappropriate ones. The third round will be to reassess your rating scores in light of the result of round two.
In order to achieve meaningful results that would in turn benefit the industry, I seek your kind assistance in completing the three rounds and returning the questionnaires along with any comments and/or extra information that may in your opinion enhance the results of this research work. The supplied information will be kept strictly confidential and used only for this study. If any item is unclear, kindly contact me at the above phone number. Your attention and assistance in this regard are greatly appreciated and I look forward to your early reply, preferably before
Wednesday 19 October 2005.
Yours Sincerely

342
Your Current Organization :____________________________________
Your Name :________________________________________________
Your Current Position :______________________________________________
Your Phone :__________________________
How many years have you been working in the construction industry?. ______Years.
Existing literature and the findings of this research work indicate that design changes are common almost in all construction projects across the globe. Design changes are defined as any addition, omission or modification to the original scope of work after the consultancy contract has been signed or modifications to the existing design.
These changes are caused by many reasons in which the clients are the most common source. Design changes could be minor ones related to design development which have no or relatively low cost and time effect. However, they could be major ones related to new ideas or changing the principle of the original design which, in turn, require re-planning and re-designing that might lead to major cost and time effects.
The assessment of the consultancy extra cost associated with the modification of the structural design on RCC buildings stands to date as one of the problem in the construction industry that need to be addressed so that the most likely disputes in this regard might be at least minimized if not totally eliminated. Hence, one of the main objectives of this study is to develop practical guidelines for improving the consultancy design documents with respect to managing the design changes that have not been given yet the required level of attention.

343
(1) The scopes of the engineering consultancy services to be provided shall be clearly defined in the consultancy contract documents. The scope of the work shall be divided into separate sections according to the nature, similarity and complexity of each part of the project (e.g. feasibility studies, similar buildings, roads, landscaping, building services, boundary walls, etc). Each defined scope of services such as the above examples shall have its own cost item(s) in the consultancy contract document.
: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
(2) Each consultancy scope of work shall be divided into a preliminary design phase and a detailed design phase wherever applicable. Each phase shall be clearly defined in the consultancy contract document and shall have its own cost item(s).
: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
(3) A clear definition for what is to be considered design changes shall be included in the consultancy contract document
: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------

344
(4) A clear method for assessing the cost of the design changes shall be included in the consultancy contract document at the tender stage
: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
(5) For large scale projects, especially fast track ones where the construction work is required to start before completion of the design, it is advisable to make a provision in the consultancy contract document at the tender stage to allocate certain design members specifically for design changes and to be paid on an agreed full/part time monthly basis for a particular duration. This requirement shall be reviewed on a regular basis to make any adjustment if deemed necessary
: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..

345
(1) An initial agreement and formal instructions to carry out the design changes shall be provided and approved by the authorised persons
: ---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
(2) Each claimed design change shall be given a chronological reference number
: ---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
(3) Each claimed design change shall be well documented in a pre-defined standard form. The form shall include the project name, the contract number, the variation reference number, date of issuing the variation, the name and the designation of the person who issued the change, brief details of the reasons for the changes and the nature and the extent of the changes highlighting any possible impacts on cost and programme. This form shall be submitted along with all relevant drawings and/or calculations to the main contact person along with a cover letter (copied to all concerned people) confirming that the design will be revised per the instruction and the associated cost will be reimbursed with reference to the agreed method of assessing the cost of the design changes.
: ---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------

346
(4) A record shall be kept for the status of the completed design at the time of introducing the changes. This shall include all the drawings and calculations before modifying the design as a back up for the claims
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
(5) For additional works, it is advisable to negotiate the cost of the design and agree on a lump- sum basis
: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
(6) The cost of each claimed design change shall be assessed and settled down as early as possible. It is advisable not to accumulate un-settled claims to very late stages
: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------

347
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..
……………..………………………………………………………………………..

APPENDIX G
ROUND THREE DELPHI QUETIONNAIRE SURVEY
348

349
Amer bin Salim Al-Harthy
P.O. Box 411, PC 413, Ibra
Sultanate of Oman
Telephone No. 99217037
Fax No. 24736788
University Technology Malaysia
Construction Technology and Management Centre
Faculty of Civil Engineering
(Guidelines for managing the design changes in RCC buildings)
_ ___________________________________________________________________
Your Current Organization : ______________________________________
Your Name : __________________________________________________
____________________________________________________________________
Date: …………………..
Dear Sir;
Thanks for replying the round two questionnaire which was intended to determine the important level of each guideline that were obtained in round one and to eliminate inappropriate ones. The attached questionnaire is the third and the final round. It is intended to reassess your rating scores in light of the result of round two and to eliminate inappropriate ones. Attached is also your reply on round two questionnaire for your reference and comparison with the overall results of round two. I seek again your kind assistance in completing this round and returning round two and round three questionnaires preferably before
Tuesday 8 th of November 2005. Your attention and assistance in this regard are greatly appreciated
Yours Sincerely
Amer Al-Harthy

350
The following is a list of guidelines for improving the consultancy design documents
with respect to managing the design changes in RCC buildings which have been developed from your contribution in round one questionnaire. You have also given in round two of this questionnaire survey your opinion on the important level of each guideline. To complete the requirement of this survey, this round is the final one and is formulated for you to reconsider your previous replies if deemed necessary in light of the result of round two questionnaire. Please tick ( √ ) on your revised opinion in the following table if it is different from your previous one.
No. of Replies
Guideline
(1) The scopes of the engineering consultancy services to be provided shall be clearly defined in the consultancy contract documents
(2) Any existing information related to the proposed work shall be clearly defined in the consultancy contract documents and shall be available during the tender stage including the history of the site, pervious site investigations, existing structures, underground facilities, etc.
(3) Any restrictions on the programme of the work, on the flow of the design information and any special design requirements shall be clearly defined in the consultancy contract design documents.
(4) The consultancy scope of works shall be divided into separate sections according to the nature, similarity and complexity of each part of the project
(e.g. feasibility studies, similar buildings, roads, landscaping, building services, boundary walls, etc)
7 - -
5 2 -
4 3 -
1 6 -
V.I
I
N.I
V.I
I
N.I
V.I
I
N.I
V.I
I
N.I

Section A : Continue
351
No. of Replies
Guideline
(5) Each defined consultancy scope of work shall be divided into a preliminary design phase and a detailed design phase wherever applicable. Each phase shall be clearly defined in the consultancy contract document and shall have its own cost item(s).
(6) A clear definition for what is to be considered design changes shall be included in the consultancy contract document
(7) Clear methods for assessing the cost of the design changes shall be included in the consultancy contract document at the tender stage
1 5 1
7 - -
5 2 -
(8) For large scale projects, especially fast track ones where the construction work is required to start before completion of the design, it is advisable to make a provision in the consultancy contract document at the tender stage to allocate certain design members specifically for design changes and to be paid on an agreed full/part time monthly basis for a particular duration. This requirement shall be reviewed on a regular basis to make any adjustment if deemed necessary
- 7 -
V.I
I
N.I
V.I
I
N.I
V.I
I
N.I
V.I
I
N.I

352
The following is a list of guidelines for managing the claims of the design changes in RCC buildings which have been developed from your contribution in round one questionnaire. You have also given in round two of this questionnaire survey your opinion on the important level of each guideline. To complete the requirement of this survey, this round is the final one and is formulated for you to reconsider your previous replies if deemed necessary in light of the result of round two questionnaire.
Please tick ( √ ) on your revised opinion in the following table if it is different from your previous one.
No. of Replies
Guideline
(1) An initial agreement and formal instructions to carry out the design changes shall be provided and approved by the authorised persons
(2) Each claimed design change shall be given a chronological reference number and date
(3) Each claimed design change shall be well documented in a pre-defined standard form. The form shall include the project name, the contract number, the variation reference number, date of issuing the variation, the name and the designation of the person who issued the change, brief details of the reasons for the changes and the nature and the extent of the changes.
(4) Each claim shall be submitted along with all relevant drawings and/or calculations to the main contact person along with a covering letter (copied to all concerned people) confirming that the design will be revised per the received/verbal instruction.
V.I
4 3 -
I
N.I
V.I
- 7 -
I
N.I
V.I
2 5 -
I
N.I
V.I
2 5 - I
N.I

Section B : Continue
353
No. of Replies
Guideline
(5) Any possible impact on cost and program due to the design changes shall be highlighted to the client and agreed as early as possible
(6) A record shall be kept for the status of the completed design at the time of introducing the changes. This shall include all the drawings and calculations before modifying the design as a back up for the claims
(7) For additional works, it is advisable to
negotiate the cost of the design and
agree on a lump- sum basis
V.I
2 5 -
I
N.I
V.I
5 2 - I
N.I
V.I
1 1 5
I
N.I
(8) The cost of each claimed design
change shall be evaluated and settle
down as early as possible. It is
advisable not to accumulate un-settled
claims to very late stages
V.I
2 5 - I
N.I
Thanks for your reply. Your time and assistant are greatly appreciated