vii
TABLE OF CONTENTS
CHAPTER
TITLE
PAGE
DECLARATION OF THE STATUS OF THESIS
SUPERVISORS' DECLARATIONS
1
TITLE PAGE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xiv
LIST OF FIGURES
xix
LIST OF SYMBOLS
xxii
LIST OF APPENDICES
xxiii
INTRODUCTION
1
1.1 Background and Rationale
1
1.2 Problem Statement
4
1.3 Aim and Objectives
5
1.4 Scope and Limitations of the Research
6
1.5 Brief Research Methodology
7
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
3
DESIGN CHANGES
14
2.1 Introduction
14
2.2 Definitions of Design Changes
14
2.3 Classifications of Design Changes
15
2.4 Sources of Design Changes
17
2.5 Causes of Design Changes
20
2.6 Impact of Design Changes
28
2.6.1 Impact of Design Changes on Cost
31
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
Design Changes
41
2.8 Chapter Summary
45
THE PRINCIPLE OF CONSULTING
ENGINEERING PRACTICE
48
3.1 Introduction
48
3.2 Definition of the Client
49
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 Study Phase
53
3.5.2 Preliminary Design Phase
53
3.5.3 Detailed Design Phase
54
3.5.4 Tender Stage
54
3.5.5 Supervision Phase
55
3.5.6 Operation Phase
56
3.6 Methods of Charging for Consulting Services
57
3.6.1 Lump Sum Method
58
3.6.2 Salary Cost Times Multiplier Plus
Non-Salary Cost method
59
3.6.3 Cost plus Fixed Amount Method
59
3.6.4 Per Diem Method
60
3.6.5 Percentage of Construction Cost
61
3.6.6 Retainer Method
64
ix
3.7
4
5
Chapter Summary
64
THE CONSTRUCTION INDUSTRY IN OMAN
66
4.1 Introduction
66
4.2 Oman at a Glance
67
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
Omani Standards
71
4.7 Fee Assessment of the Design Changes in
Omani Standard
75
4.8 Chapter Summary
76
RESEARCH METHODOLOGY
78
5.1 Introduction
78
5.2 Literature Review
79
5.3 Interviews with Professionals
80
5.4 Case Studies
81
5.5 Questionnaire Survey
82
5.6
5.5.1 Design of the Questionnaire
83
5.5.2 Pilot Survey
85
5.5.3 Main Survey Questionnaire
85
5.5.4 The Population and the Distribution of the
Questionnaire Survey
86
5.5.5 Methods of Analysing the Questionnaire Survey
88
Methodology for Development of an Alternative
Method to Assess the Fee of Structural
Design Changes
92
5.6.1 Design Parameters and Assumption for the
Building Design
95
5.6.2 Details and Classifications of the
Selected Buildings
95
5.6.3
Source of the Structural Design of the Buildings
96
5.6.4
General Structural System for the
Buildings of this Study
97
x
5.6.5
The Principle of the Adopted Structural Design
5.7 Questionnaire for Validating the Developed Method
5.7.1
6
Design of the Questionnaire
97
99
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
Delphi Questionnaires
104
5.9.3
Identifying the Number of Professionals for the
Delphi Method
105
5.9.4
Identifying the Number of Rounds for the
Delphi Method
105
5.9.5
Format of the Delphi Rounds for this Research
106
5.10 Chapter Summary
106
DATA COLLECTION
108
6.1
Introduction
108
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
Design Changes and their Limitations
119
Case Studies Results
121
6.3.1 Case Study One
121
6.3.2 Case Study Two
123
6.3.3 Case Study Three
125
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
Structural Design Changes
131
Questionnaire Survey Result
132
6.3
6.4
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
141
Impacts of Design Change
6.4.6 Corrective Actions and Preventive
Measures to Minimize the Avoidable
Design Changes
144
6.4.7
Preferences of Using the Existing
Methods for Assessing the Fee
of Design Changes
149
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
Construction Method
153
6.4.8.3 Limitations of the Area Unit Rate Method 154
6.4.8.4 Limitations of the Lump-Sum Method
7
157
6.5 Chapter Summary
158
DEVELOPMENT OF THE PROPOSED METHOD
TO ASSESS THE FEE OF THE STRUCTURAL
DESIGN CHANGES IN RC BUIDLINGS
160
7.1 Introduction
160
7.2 Preliminary Structural Design Phase
161
7.2.1
Locations of the Structural Members
161
7.2.2
Load Calculations
162
7.2.3
Sizing the Structural Members
163
7.2.4
Miscellaneous Structural Elements
166
7.3 Detailed Structural Design Phase
166
7.4 Preliminary Structural Drafting Phase
168
7.5 Detailed Structural Drafting Phase
170
7.6
170
General Approach for Developing the Proposed Method
7.7 Design by Manual Method
7.7.1
Preliminary Design and Drafting for
One Floor Buildings
172
172
xii
7.7.2
Detailed Design and Drafting for
One Floor Buildings
176
7.7.3
Preliminary Design and Drafting for
Two Floors Buildings
181
7.7.4
Detailed Design and Drafting for
Two Floors Buildings
185
7.7.5
Preliminary Design and Drafting for
Three Floors Buildings
189
7.7.6
Detailed Design and Drafting for
Three Floors Buildings
194
7.7.7
Preliminary Design and Drafting for
Four Floors Buildings
197
7.7.8
Detailed Design and Drafting for
Four Floors Buildings
202
7.7.9
Comparison of the Preliminary Design for
the Four Types Buildings
205
7.7.10 Comparison of the Detailed Design for
the Four Types Buildings
206
7.7.11 Comparison between the Preliminary and
Detailed Design
208
7.8 Design Based on STAAD Pro. Software
210
7.8.1 Preliminary Design and Drafting by
STAAD Pro for One Floor Buildings
211
7.8.2
Detailed Design and Drafting by
STAAD Pro for One Floor Buildings
216
7.8.3
Preliminary Design and Drafting by
STAAD Pro for Two Floors Buildings
220
7.8.4
Detailed Design and Drafting by
STAAD Pro for Two Floors Buildings
224
7.9 Suggested Method for Assessing the Fee of the
Structural Design Changes
228
7.10 Illustration for Using the Proposed Method
231
7.10.1 Example 1, One Floor Building
231
7.10.2 Example 2, Two Floors Building
234
7.11 The Result of the Validation
238
7.12 Chapter Summary
240
xiii
8
DEVELOPMENT OF THE GUIDELINES
FOR MANAGING DESIGN CHANGES
242
8.1 Introduction
242
8.2 Initial List of Guidelines for Improving Consultancy
Design Documents
242
8.3 Initial List of Guidelines for Managing the Claims of
Design Changes
245
8.4 Validation of the Developed Guidelines
246
8.5 The Delphi Round One Questionnaire
247
8.5.1 The Result of the Delphi Round One
Questionnaire
8.6 The Delphi Round Two Questionnaire
8.6.1
The Result of the Delphi Round Two
Questionnaire
8.7 The Delphi Round Three Questionnaire
8.7.1 The Result of the Delphi Round Three
Questionnaire
9
247
248
248
252
253
8.8 Chapter Summary
254
CONCLUSIONS AND RECOMMENDATIONS
245
9.1 Introduction
255
9.2 Conclusions
256
9.3 Contributions of the Research
263
9.4 Suggestions for Further Research
263
REFERENCES
Appendices A - G
265
277 - 353
xiv
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Actual Causes of Changes in the UK
18
2.2
Importance Indexes of Sources of
Changes in Saudi Arabia
19
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 of Changes on Projects
30
2.7
Project Size and Changes Measurer
32
2.8
Causes and Cost of Changes
34
2.9
Quantitative Effect of Disruptions
38
3.1
Converted Building Scale for Structural Works
in Buildings Expressed As A % of Building Cost
63
4.1
No. of Building Permits, Estimated Cost and Type of Building
70
4.2
Consulting Firms Grades
72
5.1
Ranking System for the Questionnaire of this Study
using Likert (Ordinal) Scale
89
5.2
Basic Buildings Details
96
6.1
Result of the Interviews with Consultants
110
6.2
Result of the Interviews with Contractors
112
6.3
Result of the Interviews with Clients
114
xv
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
Design Changes
124
6.7
Case Study Three - Causes, Sources and Fee of
Design Changes
127
6.8
Case Studies - Impact on Cost
130
6.9
Case Studies - Impact on Schedule
131
6.10
Main Scores (MS) and Ranks (R) for Causes of
Design Changes Due to Clients
133
6.11
Test for Agreement on the Ranking for Causes of
Design Changes Due to Clients
134
6.12
Main Scores (MS) and Ranks (R) for Causes of
Design Changes Due to Consultants
136
6.13
Test for Agreement on the Ranking for Causes of
Design Changes Due to Consultants
137
6.14
Main Scores (MS) and Ranks (R) for Causes of
Design Changes Due to Contractors
139
6.15
Test for Agreement on the Ranking for Causes of
Design Changes Due to Contractors
139
6.16
Main Scores (MS) and Ranks (R) for Sources
of Design Changes
140
6.17
Test for Agreement on the Ranking for Sources
of Design Changes
141
6.18
Main Scores (MS) and Ranks (R) for Impacts
of Design Changes
142
6.19
Test for Agreement on the Ranking for Impacts
of Design Changes
143
6.20
Main Scores (MS) and Ranks (R) for Corrective
Actions and Preventive Measures to Minimize
the Avoidable Design Changes
145
xvi
6.21
Test for Agreement on the Ranking for
Corrective Actions and/or Preventive Measures
to Minimize the Avoidable Design Changes
149
6.22
Main Scores (MS) and Ranks (R) for Preference
of Existing Methods for Assessing the Fee
of Design Changes
150
6.23
Main Scores (MS) and Ranks (R) for
Limitation(s) of the Man-Hours Method
151
6.24
Main Scores (MS) and Ranks (R) for Limitation(s)
of the Percentage of Construction Cost Method
153
6.25
Main Scores (MS) and Ranks (R) for
Limitation(s) of the Area Unit Rate Method
155
6.26
Main Scores (MS) and Ranks (R) for
Limitation(s) of the Lump-Sum Method
157
7.1
Times, in Minutes, and Percentage of Time for
Preliminary Structural Design (One Floor Buildings)
172
7.2
Times, in Minutes, and Percentage of Time for
Preliminary Structural Drafting (One Floor Buildings)
173
7.3
Percentage of Time for Preliminary Structural
Design and Drafting (One Floor Buildings)
174
7.4
Times, in Minutes, and Percentage of Time for
Detailed Structural Design (One Floor Buildings)
177
7.5
Times, in Minutes, and Percentage of Time for
Detailed Structural Drafting (One Floor Buildings)
178
7.6
Percentage of Time for Detailed Structural
Design and Drafting (One Floor Buildings)
179
7.7
Times, in Minutes, and Percentage of Time for
Preliminary Structural Design (Two Floors Buildings)
182
7.8
Times, in Minutes, and Percentage of Time for
Preliminary Structural Drafting (Two Floors Buildings)
183
7.9
Percentage of Time for Preliminary Structural
Design and Drafting (Two Floors Buildings)
184
7.10
Time, in Minutes, and Percentage of Time
For Detailed Structural Design (Two Floors Buildings)
186
xvii
7.11
Time, in Minutes, and Percentage of Time
for Detailed Structural Drafting (Two Floors Buildings)
187
7.12
Percentage of Time for Detailed Structural
Design and Drafting (Two Floors Buildings)
188
7.13
Times, in Minutes, and Percentage of Time for
Preliminary Structural Design (Three Floors Buildings)
190
7.14
Times, in Minutes, and Percentage of Time for
Preliminary Structural Drafting (Three Floors Buildings)
191
7.15
Percentage of Time for Preliminary Structural
Design and Drafting (Three Floors Buildings)
192
7.16
Times, in Minutes, and Percentage of Time for
Detailed Structural Design (Three Floors Buildings)
194
7.17
Times, in Minutes, and Percentage of Time for
Detailed Structural Drafting (Three Floors Buildings)
195
7.18
Percentage of Time for Detailed Structural Design and
Drafting (Three Floors Buildings)
196
7.19
Times, in Minutes, and Percentage of Time for
Preliminary Structural Design (Four Floors Buildings)
198
7.20
Times, in Minutes, and Percentage of Time for
Preliminary Structural Drafting (Four Floors Buildings)
199
7.21
Percentage of Time for Preliminary Structural Design
and Drafting (Four Floors Buildings)
200
7.22
Times, in Minutes, and Percentage of Time for Detailed
Structural Design (Four Floors Buildings)
202
7.23
Times, in Minutes, and Percentage of Time for Detailed
Structural Drafting (Four Floors Buildings)
203
7.24
Percentage of Time for Detailed Structural Design
and Drafting (Four Floors Buildings)
204
7.25
Time, in Minutes, and Percentage of Time for
Preliminary and Detailed Structural Design and Drafting
208
7.26
Times, in Minutes, and Percentage of Time for
Preliminary Structural Design based on STAAD Pro
Design Software (One Floor Buildings)
212
xviii
7.27
Percentage of Time for Preliminary Structural Design
and Drafting Based on STAAD Pro Design Software
(One Floor Buildings)
213
7.28
Times, in Minutes, and Percentage of Time for Detailed
Structural Design based on STAAD Pro Design Software
(One Floor Buildings)
216
7.29
Percentage of Time for Detailed Structural Design
and Drafting based on STAAD Pro Design Software
(One Floor Buildings)
217
7.30
Times, in Minutes, and Percentage of Time for Preliminary
Structural Design based on STAAD Pro Design Software
(Two Floors Buildings)
220
7.31
Percentage of Time for Preliminary Structural Design
and Drafting based on STAAD Pro Design Software
(Two Floors Buildings)
221
7.32
Times, in Minutes, and Percentage of Time for Detailed
Structural Design based on STAAD Pro Design Software
(Two Floors Buildings)
224
7.33
Percentage of Time for Detailed Structural Design
and Drafting based on STADD Pro Design Software
(Two Floors Buildings)
225
7.34
Percentage of Time for Preliminary Structural Design
and Drafting (One Floor to Four Floors Buildings)
229
7.35
Percentage of Time for Detailed Structural Design
and Drafting (One Floor to Four Floors Buildings)
230
7.36
Questionnaire Result for the Validation of the POF Method
239
8.1
Delphi Round Two Results: Relative Importance
Level of each Guideline for Improving the Consultancy
Design Documents
249
8.2
Delphi Round Two Results: Relative Importance
Level of each Guideline for the Claims of the
Design Changes
251
xix
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Research Methodology Flow Chart
8
2.1
Causes of Changes in Hong Kong
25
2.2
Planned and Actual Loading Curves
36
2.3
Effects of Change within Phase
39
2.4
Construction Change and Construction Productivity
39
2.5
Design Change and Design Productivity
40
3.1
Stages in Projects’ Design Cycle
52
3.2
Median Basic Fees as a Percentage of Net
Construction Cost
62
5.1
Type of Organization Represented
87
5.2
Distribution Profiles of Work Experience of the
Three Groups of Survey Respondents
88
7.1
Percentages of Time for the One Floor Buildings
at Preliminary Design Stage based on Manual Method
176
7.2
Percentages of Time for the One Floor Buildings at
Detailed Design Stage based on Manual Method
181
7.3
Percentages of Time for the Two Floors Buildings
at Preliminary Design Stage based on Manual Method
185
7.4
Percentages of Time for the Two Floors Buildings at
Detailed Design Stage based on Manual Method
189
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
193
xx
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
197
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
201
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
205
7.9
Comparisons between Percentages of Time to Design
Main Structural Members for the Four Buildings at
Preliminary Design Stage
206
7.10
Comparisons between Percentages of Time to Design
Main Structural Members for the Four Buildings at
Detailed Design Stage
207
7.11
Comparison between Percentages of Time for
Preliminary and Detailed Design Stages
209
7.12
Percentages of Time for the One Floor Buildings at
Preliminary Design Stage based on STAAD Pro
Design Software
214
7.13
Comparison between Manual Design Vs. STAAD Pro
Design Software for One Floor Buildings at Preliminary
Design Stage
215
7.14
Percentages of Time for the One Floor Buildings
at Detailed Design Stage based on STAAD Pro
Design Software
218
7.15
Comparison between Manual Design Vs. STAAD Pro
Design Software for the Three Buildings of One Floor each
at Detailed Design Stage
219
7.16
Percentages of Time for the Two Floors each
at Preliminary Design Stage based on STAAD Pro
Design Software
222
7.17
Comparison between Manual Design Vs. STAAD Pro
Design Software for the Three Buildings of Two Floors
each at Preliminary Design Stage
223
7.18
Percentages of Time for the Two Floors Buildings
at Detailed Design Stage based on STAAD Pro
Design Software
226
xxi
7.19
Comparison between Manual Design Vs. STAAD Pro
Design Software for the Three Buildings of Two Floors
each at Detailed Design Stage
227
7.20
Original Plinth (Ground) Beams Plan
232
7.21
Modified Plinth (Ground) Beams Plan
232
7.22
Original Roof Slabs/Beams Plan
233
7.23
Modified Roof Slabs/Beams Plan
233
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
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
OCC
-
Original Contract Fee
MS
-
Mean Score
N
-
Number of responses
Nf
-
total number of responses
NMM
-
Number of the Modified structural Members
TNM
-
Total Number of the structural Members
S
-
Score given to each factor as ranked by the respondents
xxiii
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Extract from Standard Form of Agreement and
Conditions for Consultancy Services for Building and
Civil Engineering Works (1987)
277
B
Questionnaire Survey – Second Stage
284
C
Architectural Plans and Elevations
296
D
Typical Structural Design and Detail
321
E
Questionnaire for Validating the POF Method
330
F
Round One Delphi Questionnaire Survey
340
G
Round Three Delphi Questionnaire Survey
346