Horizontal Formwork Design Optimization & Selection System Using Genetic Algorithms

The American University in Cairo
School of Science and Engineering
Horizontal Formwork Design Optimization & Selection System
Using Genetic Algorithms
A Thesis Submitted to
The Department of Construction Engineering
in partial fulfillment of the requirements for
the degree of Master of Science
in Construction Management
By
Ramy Mohamed Mahmoud Hassan Ghowiba
B.Sc. in Construction Engineering, 2013
Under the Supervision of
Dr. Ossama Hosny
Dr. Khaled Nassar
Professor
Department of Construction
and Architectural Engineering
The American University in Cairo
Associate Professor
Department of Construction
and Architectural Engineering
The American University in Cairo
May 2016
i
Acknowledgement
There is no better opportunity than this to express my deepest gratitude to everyone who helped
me throughout my personal and academic life, and aid me in developing my knowledge and
academic standing. I would like first to thank my family, including my mother, father, my
wife(Heba), my brother, and my coming child for their continuous support, and making this
research attempt possible through their trust and inspiration.
I would also like to thank Dr. Ossama Hosny, and Dr. Khaled Nassar for their continuous
support not only in this research paper but throughout my undergraduate, and graduate studies, I
have learned from them a great deal of information that aids me in my working field daily.
Thanks also go to all of my childhood friends and college friends; especially those who gave me
continuous support, and feel of trust throughout my life.
Special Thanks for Ibrahim Abotaleb, Osama Mahmoud, Tareq Nabil, and Amr Mosatafa Fathy
for their help in my research.
I would like to send my sincere appreciation for Awad S.Hanna, whom I never met; however, his
work and incredible knowledge in the formwork industry helped me a lot in this research.
Finally, Thanks for The American University in Cairo for giving me the opportunity to study
both my undergraduate and graduate studies in this beloved university with a selection of the
finest construction professors in Egypt.
ii
Abstract
Concrete works in most of the construction projects can be broken down into three main items;
Formwork, Steel work, and concreting, No doubt, concrete works account for a large portion of
construction projects budgets. As stated by Awad S. Hanna (1999), formwork material and labor
can account for 40 to 60 percent of the cost of concrete works; however this percentage can vary
slightly from country to another. That is why it is important to select an appropriate formwork
system for a project; otherwise the project cost will be affected negatively. Formwork systems
can be classified by their function into vertical and horizontal formwork systems, where
horizontal formwork is used to support slabs, and beams, while the vertical formwork supports
vertical elements like the columns. There have been attempts to optimize the design of
formwork, and create a systematic approach for formwork selection based on expert opinion for
both vertical and horizontal formwork systems. Despite the fact that expert based systems have
been successfully applied to different projects; however, incorporating formwork design
optimization with formwork selection system in one research or model is still not applied;
especially for horizontal formwork systems. Therefore, the model developed in this research
tackles the gap in literature, concerning the need for a formwork selection system that is not
based on experts' opinion, and that can output a purchase cost and detailed quantity take-off with
reasonable accuracy for the selected formwork system out of conventional wood formwork
system, props system, frames system, and cuplock system for regularly shaped projects. In the
research, a cost equation was developed, in order to compare all the formwork systems, while
considering all the parameters affecting that selection. The model is developed using Microsoft
Excel 2007 and Evolver 5.5(Palisade Decision tools), which is an excel add in that uses the
Evolutionary algorithms (Genetic algorithm) optimization concept. In order to validate the
model, the outputted designs were compared with real-life projects design calculation sheets
prepared by Acrow Masr formwork company, while the quantity take-offs outputted from the
model were compared to manual calculations, and yielded an accuracy of more than 90 percent.
After the model output was validated, it was successfully applied to a high-rise construction
project in Egypt, and the most appropriate formwork system for that project was outputted with a
purchase cost, and design parameters. The formwork selection system was applied to an
optimized low income housing plan developed in previous research; highlighting the appropriate
formwork systems to be used based on the number of formwork uses per year; in addition to
developing a complete formwork design drawings for these selected systems.
iii
Contents
Acknowledgement ........................................................................................................................................ ii
Abstract ........................................................................................................................................................ iii
List of Figures ............................................................................................................................................. vii
List of Tables ................................................................................................................................................ x
Nomenclature .............................................................................................................................................. xii
1 Chapter 1: Introduction .............................................................................................................................. 2
1.1 General Introduction ........................................................................................................................... 2
1.2 Importance of Formwork selection for a construction project& factors affecting Formwork
Selection for a project ............................................................................................................................... 5
1.3 Problem Statement .............................................................................................................................. 6
1.4 Research Objective ............................................................................................................................. 7
1.5 Research Methodology ....................................................................................................................... 8
1.6 Research Scope ................................................................................................................................. 10
1.7 Thesis Organization .......................................................................................................................... 11
2 Chapter 2: Horizontal Formwork Systems & Design .............................................................................. 13
2.1 Horizontal Formwork Systems ......................................................................................................... 13
2.1.1 Conventional Wood system ..................................................................................................... 13
2.1.2 Conventional Metal (aluminum) system .................................................................................. 13
2.1.3 Joist-Slab forming system .......................................................................................................... 14
2.1.4 Dome forming system ................................................................................................................ 14
2.1.5 Flying formwork system ............................................................................................................ 15
2.1.6 Column Mounted Shoring system.............................................................................................. 17
2.1.7 Tunnel Formwork system .......................................................................................................... 18
2.1.8 Comparison between different Horizontal Formwork system ................................................... 19
2.1.9 New formwork system introduced in the market ....................................................................... 20
2.2 Formwork Design ............................................................................................................................. 20
2.2.1 Formwork Design equations, where the spans between members are the output ...................... 21
2.2.2 Formwork Design equation for stresses calculation .................................................................. 22
3 Chapter 3 literature review....................................................................................................................... 25
3.1 Formwork Design Optimization ....................................................................................................... 25
3.2 Formwork Selection System ............................................................................................................. 29
3.2.1 Expert based systems ................................................................................................................. 29
3.2.2 Optimization based systems ....................................................................................................... 35
3.3 Formwork Economics ....................................................................................................................... 38
3.3.1 Material cost............................................................................................................................... 38
3.3.2 Maintenance cost........................................................................................................................ 39
iv
3.3.3 Modification cost ....................................................................................................................... 39
3.4 Optimization Technique .................................................................................................................... 39
3.4.1 Genetic algorithms ..................................................................................................................... 41
4 Chapter 4: Model Formulation................................................................................................................. 45
4.1 Background and Model Methodology .............................................................................................. 45
4.2
Formwork Design ....................................................................................................................... 47
4.2.1 Design Concept .......................................................................................................................... 47
4.2.2 Loads .......................................................................................................................................... 48
4.2.3 Sheathing.................................................................................................................................... 49
4.2.4 Secondary Beam (Joist) ............................................................................................................. 50
4.2.5 Main Beam (Stringer) ................................................................................................................ 52
4.2.6 Props System .............................................................................................................................. 54
4.2.7 Frames System ........................................................................................................................... 56
4.2.8 Cuplock System ......................................................................................................................... 57
4.2.9 Wood Shores .............................................................................................................................. 60
4.3 Quantity Take-Off ............................................................................................................................. 60
4.3.1 Props System .............................................................................................................................. 61
4.3.2 Frames system ............................................................................................................................ 63
4.3.3 CupLock..................................................................................................................................... 66
4.3.4 Wood Shore ............................................................................................................................... 67
4.3.5 Adjacent areas ............................................................................................................................ 67
4.3.6 Main Beam ................................................................................................................................. 68
4.3.7 Secondary Beam ........................................................................................................................ 71
4.3.8 Sheathing.................................................................................................................................... 72
4.4 Cost Estimation ................................................................................................................................. 73
4.5 Optimization ..................................................................................................................................... 74
4.5.1 Variables .................................................................................................................................... 74
4.5.2 Constraints ................................................................................................................................. 75
4.5.3 Objective Function ..................................................................................................................... 76
4.5.4 Software used for optimization .................................................................................................. 76
4.6 Program limitations ........................................................................................................................... 77
4.7 User input .......................................................................................................................................... 77
4.7.1 Geometry.................................................................................................................................... 77
4.7.2 Material related Data .................................................................................................................. 78
4.7.3 Cost related data ......................................................................................................................... 80
4.8 User output ........................................................................................................................................ 81
v
5 Chapter 5: Model Verification, Validation & Application ...................................................................... 84
5.1 Formwork Design Verification ......................................................................................................... 84
5.1.1 Porto Cairo Shorebrace System ................................................................................................. 84
5.1.2 Secon Nile Tower European Prop System ................................................................................. 89
5.2 Quantity Take-off Verification ......................................................................................................... 93
5.2.1 Props System .............................................................................................................................. 95
5.2.2 Frames System ......................................................................................................................... 100
5.2.3 Cuplock Ledger ........................................................................................................................ 101
5.2.4 Beams ....................................................................................................................................... 102
5.3 Formwork Selection System Validation-Secon Nile Towers Project case study............................ 104
5.3.1 Secon Nile Tower-System Selected by Contractor .................................................................. 105
5.3.2 Optimization using Evolver 5.5 ............................................................................................... 109
5.3.3 Formwork Selection System output ......................................................................................... 111
5.3.4 Comparison between the Outputted Formwork System, and the Used formwork system in
Secon Nile Towers ............................................................................................................................ 112
5.3.5 Sensitivity of Formwork selection decision ............................................................................. 113
5.4 Formwork Selection System Application on Low income housing................................................ 114
5.4.1 Optimization Concept .............................................................................................................. 114
5.4.2 Data used in optimization ........................................................................................................ 116
5.4.3 Optimization Process ............................................................................................................... 116
5.4.4 Low income Housing Formwork Selection, and Design optimization .................................... 118
5.4.5 Conventional Wood formwork design ..................................................................................... 119
5.4.6 Shorebrace formwork design ................................................................................................... 121
6 Chapter 6: Conclusion & Recommendations ......................................................................................... 126
6.1 Summary & Conclusion .................................................................................................................. 126
6.2 Research outcomes & Contributions............................................................................................... 128
6.3 Recommendations ........................................................................................................................... 129
6 References .............................................................................................................................................. 130
Appendix ................................................................................................................................................... 132
Visual Basic Code for Graphical interface ........................................................................................... 133
vi
List of Figures
Figure 1: Summary of the False work systems used in the research ............................................................ 3
Figure 2: Summary of the decking options used in the research .................................................................. 3
Figure 3: Factors Affecting the Selection of a formwork system ................................................................. 6
Figure 4: Formwork types used in Korea...................................................................................................... 7
Figure 5: Research methodology flowchart summary .................................................................................. 9
Figure 6: Thesis Organization ..................................................................................................................... 11
Figure 7: Horizontal Formwork Systems classification .............................................................................. 13
Figure 8: One-Way joist slab system .......................................................................................................... 14
Figure 9: Dome forming system for waffle slab ......................................................................................... 14
Figure 10: Truss Flying Form components ................................................................................................. 15
Figure 11: Flying Formwork cycle ............................................................................................................. 15
Figure 12: Dokamatic cycle ........................................................................................................................ 16
Figure 13: Lowering the steel prop in Dokamatic system .......................................................................... 16
Figure 14: C-Fork for Dokamatic System................................................................................................... 17
Figure 15: TLS system for Dokamatic formwork ....................................................................................... 17
Figure 16: Components of column mounted shoring system...................................................................... 17
Figure 17: Column mounted shoring system .............................................................................................. 17
Figure 18: Components of Tunnel formwork system ................................................................................. 18
Figure 19: Early Striking formwork system-Acrow example…………………………………………......20
Figure 20: Panel Formwork System Example-Sky deck system by Peri …………………………………20
Figure 21: Joist Spacing versus formwork cost ……………….………………………………………….25
Figure 22: Optimized Slab Formwork Design Flow Chart ......................................................................... 26
Figure 23: Conventional Slab Formwork Design flow Chart ..................................................................... 26
Figure 24: Dynamic Programming flowchart for Formwork Design Optimization ................................... 28
Figure 25: Formwork Knowledge acquisition system procedures .............................................................. 29
Figure 26: Example of formwork Knowledge Based model output ........................................................... 30
Figure 27: Formwork selection system questioner output .......................................................................... 31
Figure 28: Output of Fuzzy logic model for formwork selection ............................................................... 31
Figure 29: Fuzzy logic variables and output ranges for formwork selection system .................................. 32
Figure 30: System validation questioner…………………………………………………………………..32
Figure 31: Factors affecting horizontal formwork selection………………………………………………33
Figure 32: Decision Tree Concept in formwork selection system .............................................................. 34
Figure 33: Boosted Decision tree concept in formwork selection system .................................................. 34
Figure 34: Boosted decision tree output for formwork selection system with confidence level ................ 34
Figure 35: Flexible Table form components ............................................................................................... 35
Figure 36: Geometry of the available and unavailable areas, units, and subunits ...................................... 35
Figure 37: The formwork layout divided into regions ................................................................................ 36
Figure 38: Optimized formwork design layout ........................................................................................... 36
Figure 39: Free form shell structures .......................................................................................................... 37
Figure 40: Free form structures……………………………………………………………………………37
Figure 41: Model optimization output ........................................................................................................ 38
Figure 42: Genetic Algorithms structure. ................................................................................................... 41
Figure 43; Chromosome in genetic algorithm ........................................................................................... 42
Figure 44: One Point Crossover in Genetic Algorithms ............................................................................ 42
Figure 45: Mutation Example in Genetic algorithms ................................................................................. 43
Figure 46: The current formwork selection process followed in Egypt ...................................................... 45
Figure 47: Formwork Selection process followed in the formwork selection model……………………..46
Figure 48: Summary of the Quantity Take-off procedures followed in the model………………………..60
Figure 49: Props obstructed by un-available area (column) check………………………………………..61
vii
Figure 50: Main beam cantilever check example…………………………………………………………62
Figure 51: Main Beam Cantilever check directions .................................................................................... 62
Figure 52: Example used for calculation of Frames quantities in un-available areas ................................. 64
Figure 53: Frames obstructed by unavailable area ...................................................................................... 66
Figure 54: Added frames to account for the partially obstructed frame by un-available area .................... 66
Figure 55: Adjacent areas check ................................................................................................................. 67
Figure 56: Adjacent areas sides check ........................................................................................................ 67
Figure 57: Main Beam obstructed by un-available area ............................................................................. 69
Figure 58: Main beam obstruction Check ................................................................................................... 69
Figure 59: Arrangement of Main Beam and Secondary Beam-Main beam in Yellow, and Secondary Beam
in Red .......................................................................................................................................................... 72
Figure 60: Variables for Cuplock system…………………………………………………………………74
Figure 61: Variables for Frames system ..................................................................................................... 74
Figure 62: Variables for Props System ....................................................................................................... 74
Figure 63: Variables for Conventional Wood system ................................................................................. 74
Figure 64: Cuplock Constraints .................................................................................................................. 75
Figure 65: Frames system constraints ......................................................................................................... 75
Figure 66: Props system constraints............................................................................................................ 75
Figure 67: Conventional Wood Formwork Constraints .............................................................................. 75
Figure 68: Evolver 5.5 add in to excel 2007 ............................................................................................... 76
Figure 69: Definition of variables, constraints, and objective function (Model Definition) in Evolver ..... 76
Figure 70: Geometry Input in the model using Visual basic code………………………………………...78
Figure 71: General Design Data for user input ........................................................................................... 78
Figure 72: Material Related Properties input (H-20) Example ................................................................... 79
Figure 73: False work Material Related Properties input-Props system Example ...................................... 79
Figure 74: Cost Related Data for H20 ........................................................................................................ 80
Figure 75: Cost Related Data For European Prop....................................................................................... 80
Figure 77: Formwork Grid outputted from the model ................................................................................ 81
Figure 76: Outputted Design Data Example ............................................................................................... 81
Figure 78: Formwork Selection System Output ......................................................................................... 81
Figure 79: Porto Cairo Acrow calculation sheet one .................................................................................. 85
Figure 80: Porto Cairo Acrow calculation sheet two……………………………………………………...85
Figure 81: Porto Cairo Acrow calculation sheet three ................................................................................ 86
Figure 82: Porto Cairo Acrow calculation sheet four ................................................................................. 86
Figure 83: Secon Nile Tower Acrow calculation sheet one………………………………………………90
Figure 84: Secon Nile Tower Acrow calculation sheet two………………………………………………90
Figure 85: Secon Nile Tower Acrow calculation sheet three……………………………………………..90
Figure 86: Floor Plan Used for Quantity Take-off Verification…………………………………………..93
Figure 87: Props Manual Quantity take-off……………………………………………………………….95
Figure 88: Manual Quantity Take-off for Main Beam……………………………………………………96
Figure 89: Manual Quantity Take-off for the secondary beam…………………………………………...98
Figure 90: Manual Quantity Take-off for Frames system using Acrow shorebrace frame dimensions…100
Figure 91: Cuplock Ledger manual quantity take-off……………………………………………………102
Figure 92: Beam One Main beam & Secondary Beam configuration…………………………………...102
Figure 93: Beam one Frame, and main beam plan………………………………………………………102
Figure 94: Secon Nile tower Residential Slab Post tension stages………………………………………104
Figure 95: Secon Nile Tower Layout…………………………………………………………………….104
Figure 96: Secon Nile towers Residential tower 3d model………………………………………………104
Figure 97: Secon Nile Tower…………………………………………………………………………….104
Figure 98: Plan for one of the modules used for table formwork in Secon Nile Towers project………..105
Figure 99: Secon Nile Tower available and un-available area defined………………………………….106
viii
Figure 100: Secon NIle Tower Geometry Approximation………………………………………………106
Figure 101: Evolver watcher for Shore brace system-Secon Nile Towers ............................................... 110
Figure 102: Evolver watcher for European Prop-Secon Nile Towers…………………………………...110
Figure 103: Evolver watcher for Wood Formwork system-Secon Nile Towers………………………...110
Figure 104: Evolver watcher for cuplock system-Secon Nile Towers…………………………………..110
Figure 105: Sensitivity of Formwork selection system outputted decision……………………………...113
Figure 106; Low income housing plan (Fathy,2015) ................................................................................ 114
Figure 107: Low income housing beams plan compiled .......................................................................... 115
Figure 108: Low income housing Plan Areas ........................................................................................... 115
Figure 109: Low income Housing Modeling concept............................................................................... 115
Figure 110: Grid in accuracy Problem ...................................................................................................... 115
Figure 111: Evolver watcher-Cuplock system-available areas-low income housing ............................... 117
Figure 112: Evolver watcher-Shorebrace system-available areas-low income housing ........................... 117
Figure 113: Evolver watcher-European Prop-available areas-low income housing ................................. 117
Figure 114: Evolver watcher-Wood formwork-available areas-low income housing .............................. 117
Figure 115: Evolver watcher-All formwork systems-Beams-low income housing .................................. 117
Figure 116: Formwork System Selection Vs. Number of Formwork Yearly uses ................................... 118
Figure 117: Slab Wood Formwork Design for low income housing ........................................................ 120
Figure 118: Beams wood formwork design for low income housing ....................................................... 120
Figure 119: Beams Shorebrace plan-low income housing ........................................................................ 122
Figure 120: Slab Shorebrace Formwork Design for low income housing ................................................ 123
ix
List of Tables
Table 1: Comparison between different Horizontal formwork systems -based on Hanna (1999) .............. 19
Table 2: Example from the model for Design Loads calculations .............................................................. 49
Table 3: Sheathing Design checks from the Model .................................................................................... 50
Table 4: Secondary Beam Design checks outputted from the Model ......................................................... 51
Table 5: Main Beam Design Checks outputted from the model- if the main beam direction is the xdirection ...................................................................................................................................................... 53
Table 6: Main Beam Design Checks outputted from the model- if the main beam direction is the ydirection ...................................................................................................................................................... 54
Table 7: Prop Design Capacity check outputted from the model ............................................................... 55
Table 8: Prop Design Capacity from the model showing a rejected prop although it fulfills the height
requirements................................................................................................................................................ 55
Table 9: Prop Design Capacity check outputted from the model ............................................................... 57
Table 10: Cuplock Prop Capacity check outputted from the model for one prop selected ......................... 58
Table 11: Cuplock Design Procedures for more than one vertical prop selected ....................................... 59
Table 12: European Prop Available area quantity take-off example .......................................................... 61
Table 13: Example from the model for Calculating props obstructed by the unavailable area .................. 62
Table 14: Frames System Quantity Take-off .............................................................................................. 63
Table 15: Frames un-available areas Quantity Take-off checks ................................................................. 65
Table 16: Main Beam Quantity Take-off for available areas ..................................................................... 68
Table 17: Main Beam Quantity take-off example from the model ............................................................. 70
Table 18: Main Beam Quantity Take-off for un-available areas for Frames system .................................. 71
Table 19: Model Excel Sheets Description ................................................................................................. 82
Table 20: Properties of Main Beam used in Design Verification 1 ............................................................ 84
Table 21: Properties of Secondary Beam used in Design Verification 1 .................................................... 85
Table 22: Design Parameters for Porto Cairo ............................................................................................. 85
Table 23: Design Loads from the model ..................................................................................................... 86
Table 24: Plywood Design Checks from the model.................................................................................... 87
Table 25: Secondary Beam Design Checks from the model....................................................................... 87
Table 26: Design for main beam from the model ....................................................................................... 88
Table 27: Frame Capacity check from the model ....................................................................................... 88
Table 28: Other Design checks from the model.......................................................................................... 88
Table 29: Properties of Main & Secondary Beam used in Design Verification 2 ...................................... 89
Table 30: Design Parameters for Design Verification 2 ............................................................................. 89
Table 31: Design Loads from the model ..................................................................................................... 91
Table 32: Plywood Design Checks from the model.................................................................................... 91
Table 33: Secondary Beam Design Checks from the model....................................................................... 91
Table 34: Main Beam Design Check from the model................................................................................. 92
Table 35: Quantity Take-off verification Area Co-ordinates ...................................................................... 94
Table 36: Design Parameters used in the quantity take-off ........................................................................ 95
Table 37: Detailed Quantity Take-off for European Props outputted from the model ............................... 96
Table 38: Detailed Quantity Take-off for main beams ............................................................................... 97
Table 39: Quantity Take-off Summary ....................................................................................................... 97
Table 40: Comparison between Model Secondary Beam Quantities, and Manual calculations ................. 99
Table 41: Detailed Quantity Take-off for Secondary Beam outputted from the model.............................. 99
Table 42: Frames Detailed Quantity Take-off from the model ................................................................. 101
Table 43: Crossbrace Quantity Take-off from the model ......................................................................... 101
Table 44: Cuplock ledger quantity take-off outputted from the model..................................................... 102
Table 45: Frame system detailed quantity take-off for beam one ............................................................. 103
Table 46: Secon Nile Tower available, and un-available areas co-ordinates............................................ 107
x
Table 47: Number of uses for formwork elements ................................................................................... 109
Table 48: Formwork Selection System Output ......................................................................................... 111
Table 49: Design Parameters for European Prop optimized design-Secon Nile Tower Project ............... 112
Table 50: Design parameter conventional wood formwork ...................................................................... 119
Table 51: Conventional Wood formwork system cost for low income housing ....................................... 121
Table 52: Shorebrace Design Parameters outputted from the model ........................................................ 122
Table 53: Shorebrace system cost for low income housing ...................................................................... 124
xi
Nomenclature
Symbol
Description
unit
A
Aa
Ab
As
Aua
Ap
B
b
bje
Cf
CW
Cm
CR
CH
CBQ
CBQR
CLX
CLY
CPx
CPy
d
dje
DL
DP
E
f
FX
FY
Fb
Fy
fc
FW
Fci
H
Hp
I
i
JW
area of section
Area of available area
Bearing area
Area of sheathing material
Area of un-available area
Area supported by each Shore
U-Head and P-Head Buffer distance
width of member
Effective width
material cost for one use
Concrete Weight
Maintenance cost for one use
average modification cost for one use
Clear Height of Floor
Crossbrace Quantity
Crossbrace Removed Quantity
Cuplock Ledger in X-direction (Available Area)
Cuplock Ledger in Y-direction (Available Area)
No. of Cuplock Props in the X-Direction
No. of Cuplock Props in the Y-Direction
depth of member
Effective depth
Design Load
Depreciation Per Year
modulus of Elasticity
the number of years after which maintenance is required
Sum of Frame obstructed in X-direction
sum of Frame obstructed in Y-direction
Allowable unit stress in bending
allowable unit stress in horizontal shear
actual unit stress in compression parallel to grain
Formwork weight
actual unit stress in compression perpendicular to grain
Lateral Force applied along the edge of slab
The Height of European Prop needed
moment of inertia
annual interest rate
Stringer Design Load
mm2
m2
m2
m2
m2
m2
m
mm
m
L.E
KPa
L.E
L.E
m
no.
no.
no.
no.
no.
no.
mm
m
KN/m2
factor
KPa
years
no.
no.
KPa
KPa
KPa
KPa
KPa
KN/m
m
mm4
factor
KN/m
xii
k
LA
La
Lc
LL
L
Ln
Ls
Lua
M
MH
N
Ny
n
OD
Pf
PW
Ps
PWCAF
PT
PH
Pm
Pma
RCLX
RCLY
R
S
SW
Sj
Ss
SH
SCPx
SCPy
ts
Tm
Um
Uma
USSFF
USCRF
w
the number of years after which modification is required
Length of Available area
Length of available area
Cantilever Span for Mean Beam
Live Load
Length of Span, Center to Center of supports
Salvage Value
Length of sheathing material
Length of un-available area
Bending moment
Main Beam Height
overall number of uses before disposal
annual number of uses
Useful life
Project Duration
Purchase Cost
Shore Design Load
Shore Capacity
present wroth compound amount factor
Plywood Thickness
Prop or Frame Height
Minimum allowable P-Head Height
Maximum allowable P-Head Height
Removed Cuplock Ledger in the X-Direction
Removed Cuplock Ledger in the Y-Direction
modification expense
Section modulus
Shore Design Load
Spacing between Joists
Spacing between Stringers
Secondary Beam Height
Sum of Cuplock ledger removed in X-Direction
Sum of Cuplock ledger removed in the Y-Direction
Slab Thickness
Periodic maintenance expense
Minimum allowable U-Head Height
Maximum allowable U-Head Height
Unified series sinking fund factor
uniform series capital recovery factor
uniform load per meter of span
xiii
years
m
m
m
KPa
mm
L.E
m
m
KN.m
m
no.
no.
years
Years
L.E
KN
KN
no.
m
m
m
m
no.
no.
L.E
mm3
KN/m
m
m
m
no.
no.
mm
L.E
m
m
no.
no.
KPa/m
ws
WA
Wa
Ws
Wa
∆
γc
∆max.
width of slab perpendicular to slab edge
Width of Available area
Width of available area
Width of sheathing material
Width of un-available area
deflection
Specific weight of concrete
Maximum deflection
xiv
m
m
m
m
m
mm
N/m3
mm
Chapter 1
Introduction
1
1 Chapter 1: Introduction
1.1 General Introduction
Formwork is simply a temporary structure that supports fresh concrete until it takes its desired
shape, and be able to support itself. Formwork can be is classified into horizontal formwork, that
supports horizontal structural elements like slabs, and beams, and vertical formwork that
supports vertical elements like columns, cores, shears walls, and retaining walls. Formwork
systems are designed in order to support loads such as fresh concrete, equipment, workers,
various impacts, and sometimes wind without collapse (Hanna, 1999). The basic components of
a horizontal formwork system are Sheathing material which acts as a mold that shapes the
concrete, Joists that acts as a secondary beam, and transfers the load to the Stringers that acts as a
main beam that transfer the load to the shores which transfers the load to the ground. In addition
to the lateral bracing, that is used to increase the capacity of the shores, by decreasing the
unsupported length (Higher buckling capacity), and resists the vertical loads like the wind.
However, nowadays new systems have been developed, in which the secondary beam was
replaced by an infill beam, and the main beam has been replaced by main decking beam. Also,
new systems have been developed that consists mainly of a panel, and this panel is supported by
a shore as the Sky deck system developed by Peri formwork company. According to Hanna
(1999), Horizontal formwork can be classified to Hand-set systems, and Crane-set systems.
Hand-Set systems are conventional wood formwork, conventional metal formwork, Joist-slab
forming, and dome forming, while crane-set systems are flying formwork, column-mounted
shoring, and tunnel forming. The model developed in this research paper is concerned with the
conventional wood formwork system, and three types of conventional metal formwork shoring
systems, and three types of joists(secondary beam), and stringers(main beam) material type
options as shown in figure 1& 2. The conventional wood formwork consists of the traditional
components of formwork discussed before, while the first conventional metal formwork system
used in the model developed in this research paper is Props formwork system. It consists of a
vertical jack or prop, that needs a special type of U-head on which the stringers rests on, this
system is commercially available in Peri and it is known as Multi-Flex system, while in Doka it
is known as Doka Flex system, and in Acrow it is known as the European Prop formwork
system.
2
Props System
Known as: European Prop in Acrow,
Multiflex in Peri
Doka Flex in Doka
Conventional Wood Formwork system
Cuplock System
Known as: SGB in the market
Cuplock in Acrow
Up Flex Shoring in Peri
Dokascaff in Doka
Frames System
Known as: Shorebrace in Acrow
PD8 Shoring tower in Peri
Load Bearing tower Staxo in Doka
Figure 1: Summary of the False work systems used in the research
H-20 Beam
Metal or aluminum beam
Know as: S-Beam in Acrow
Alu Box beam in Doka
Timber or lumber wood beam
Figure 2: Summary of the decking options used in the research
The second metal formwork system is called Frames formwork system, and it consists of a
Shoring Frame with a width and heights that vary from one formwork company to another. Each
two shoring frames are connected to each other by a cross brace, and the Frames transfers the
3
load of the slabs, to the ground through a formwork element known as a P-head. The stringers is
supported by a U-head, with an adjustable height screw, in order to be able to level the formwork
of the slab from. The Frame system is commercially available in Peri and known as PD8 Shoring
tower, while in Doka it is known as Load bearing tower Staxo, and in Acrow it is known as the
shorebrace system. The third metal formwork system is called cuplock system and it consists of a
vertical prop that has a slot each certain interval, depending on the company manufacturing the
formwork, in which a horizontal ledger can be installed in order to act as a bracing for the
system, to resists both vertical and horizontal loads. The cuplock system also consists of a Phead, and U-Head with an adjustable height screw, this system is commercially known as SGB
system, and it is known in Acrow as the cuplock formwork shoring system; in Peri it is known as
UP-Flex shoring, and in Doka this system is used for scaffolding works and it is called
Dokascaff. Moreover, the decking options considered in this model are H-20, which is a timber
I-Shaped beam that is commercially produced by Acorw, Peri, Doka, and many other formwork
companies. Then, Metal or aluminum beams, which are produced with several types depending
on the formwork company; in Acrow, they use a metal beam that is commercially known as Sbeam, while in Doka there is an aluminum beam called Alu Box beam. The last option
considered is timber or lumber conventional beams; there are several types of timber beams like
Douglas fir, Hemlock, Southern Pine, California redwood, and Eastern Spruce (S.W.Nunnally,
2007). As it is going to be discussed in the literature review section there have been many
attempts for developing formwork selection system; however, most of these systems depend on
Experts’ opinion, which might have some inaccuracy in their databases, as stated by Awad
Hanna, Jack Willenbrock and Victor Sanvido(1992) that some of the sources of error in their
knowledge-based acquisition database for formwork selection was inaccessibility to cost data,
and expert’s conflict in opinion, which are two factors that affected the outputted decision of
which formwork system to use . Accordingly, the main purpose of this paper is to develop a
framework for Formwork selection that is not based on Experts’ opinions, and to develop a
model using Microsoft Excel 2007 that can optimize the design, and select the appropriate
formwork system using Evolutionary algorithms (Genetic algorithms) using Evolver 5.5 for a
construction project from the aforementioned formwork systems with detailed quantity take-off,
and cost estimate while considering all the factors affecting formwork selection process.
4
1.2 Importance of Formwork selection for a construction project& factors
affecting Formwork Selection for a project
According to Hanna (1999) Formwork is the largest cost component for a typical multistory
reinforced concrete building; especially that formwork cost accounts for 40 to 60 percent of the
cost of the concrete frame, and for approximately 10 percent of the building cost; however this
percent can vary slightly from one country to another. Therefore, the large portion of cost
contribution in building construction shows how important it is to choose a suitable formwork
for a project; especially that, as a contractor, a suitable formwork must be chosen so as to fulfill
the projects time, cost, and quality objective, without compromising any of them. After selecting
the appropriate system for the project it is important to insure that the design of such a system is
optimized in order to eliminate any unnecessary costs paid due to having unneeded excessive
design parameter .After highlighting the importance of selecting and design optimization, the
factors affecting the formwork selection must be mentioned, and these factors are categorized by
Awad S. Hanna, et.al (1992) into four main categories which are Building Design, Job
Specification, Local Conditions, and the Supporting Organization, and the detailed breakdown of
each category is shown in figure 3. The building design is related to the type of slab system used,
the lateral loads supporting system, and the building geometry, while, the job specification factor
is related to the concrete finish desired, the cycle time needed to be achieved in the project. In
addition, the local conditions are related to the labor costs, weather conditions, and site
characteristics, finally, the supporting organization is related to the amount of support whether
on finical basis or resource-wise provided to the project.
5
Figure 3: Factors Affecting the Selection of a formwork system (Hanna et.al, 1992)
1.3 Problem Statement
As stated by Hanna (1999) that formwork cost can contribute up to 10% of the total project cost;
therefore, it is very important to select the appropriate formwork system, and optimize the design
of such a system; otherwise, the project will suffer from cost overrun, and delays due to the
wrong choice of such a system. Also, one of the most important decisions that a decision maker
in a project has to take is whether to purchase the system or rent it; this decision is important, and
if such a decision was taken, without considering the risk of rental, it might end up to be a wrong
decision economically. As it is going to be shown in the literature review chapter, there are
several formwork selection models that have been developed. However, most of these models
are expert based models, which means that they mainly depend on experts’ opinion regarding the
selection of the formwork system to use. Although, such models succeeded in outputting the
appropriate formwork system. However, there is no supporting data for the selection rather than
the experts’ opinion used in the database. Also these models did not output any design
parameters or purchase cost. Although there was a model developed that optimizes the design of
certain type of table formwork (Taehoon Kim et al.,2012), and another model that optimizes the
formwork of shell structures (Khaled Nassar and Ebrahim Aly,2012); however, still these models
are targeting special applications and systems. That is why there is a need for a model that
6
considers all the factors affecting formwork selection, in a way that can be visible to the user of
the model, and enables him/her to check any of the calculations that lead to the outputted
decision from the model. And, provide the user with a complete optimized design, and purchase
cost for the selected formwork system. As mentioned before the systems that are going to be
used in the research are Conventional wood system, Props system, Frames system, and Cuplock
system. According to Yoonseok Shin, et.al. (2012) the aluminum and conventional wood
formwork are used in about 75% of construction project in Korea, as shown in figure 4.
Although there is not any study showing the types of formwork used in each project in Egypt;
however, this percentage is expected to be higher in Egypt, where the sky deck and con-panel
systems are rarely used. Therefore, this means that the formwork systems used in this research
covers a vast number of construction projects.
Figure 4: Formwork types used in Korea (Yoonseok Shin, et. al ,2012)
1.4 Research Objective
The main objective of this research is to develop a framework for Formwork selection that is not
based on Experts’ opinions, and to develop a model using Microsoft Excel 2007 that can
optimize the design, and select the appropriate formwork system using Evolutionary algorithms
(Genetic algorithms) using Evolver 5.5 for a construction project with the least possible cost for
that system with a detailed quantity take-off, and cost estimate while considering all the factors
affecting formwork selection process developed in previous literature. The detailed objectives of
this research are to:
1. Develop a Framework for formwork design optimization and selection system that are
not expert based.
7
2. Create a design model for selected formwork systems (conventional wood formwork,
Props system, Frame system, and Cuplock system) using Microsoft Excel 2007, and
Visual basic that records the user inputted regular shape (Rectangle or Square) coordinates automatically for the drawn project geometry on excel.
3. Develop a formwork design model with the design parameters formulated as variables.
4. Create an accurate quantity take-off based on the design parameters of each formwork
system.
5. Output an accurate cost estimate for each formwork system based on quantity take-off,
and calculate both the purchase cost, and the cost that is going to be used for comparing
the different formwork systems, which includes the time cycle, number of uses, and many
other factors for formwork selection criteria that are going to be mentioned in the model
development chapter.
6. Run an optimization model using Evolver 5.5 that uses Genetic Algorithms technique in
order to optimize the design of each formwork system, to insure that each system has the
least quantities that fulfils the project objectives which are cost, time, and targeted quality
7. Provide the user with the most suitable formwork system to be used for the inputted
project, and a complete design, quantity take-off, and purchase cost for such a system.
1.5 Research Methodology
First, literature review is done in which the formwork design models developed previously was
investigated, then the formwork selection systems attempts done was identified and analyzed; in
addition to, the formwork economics considerations, which included cost equations that consider
the time value of money. Then, the used optimization technique which is genetic algorithms was
discussed in details. After going through the literature review, and identifying the gap that
existed in the literature, a model was developed for formwork selection system, and design
optimization. This model has three major categories that it passes through, which are formwork
design, quantity take-off, and cost estimate for each of the selected formwork systems discussed
in this research. These three categories is optimized using genetic algorithm until a near optimum
solution is reached. In addition, the appropriate formwork system to be used for the project is
outputted with design parameters, detailed quantity take-off, and purchase cost estimate. Finally,
the model verification, validation, and application is done. A summary of the research
methodology is shown in figure 5.
8
Literature review
Optimization
Techniques
Formwork Design
Formwork Design
optimization
Formwork
Selection System
Formwork
Economics
Model
Development
Formwork Design
Quantity take-off
Design
Optimization
Cost-Estimation
Formwork
Selection
System
Model
Validation
Figure 5: Research methodology flowchart summary
9
1.6 Research Scope
The Scope of the Work in this research paper is as follows:
1- Rectangular Shaped Areas are only considered; in other words, the model does not consider
irregularly shaped buildings.
2- Four Formwork systems are only considered, which are conventional wood formwork, props
system, frame system, and cuplock system.
3- In order to be able to optimize the formwork systems in selection, and select the most
appropriate formwork system all the factors affecting formwork selection is defined in terms of
cost.
4-Formwork design is based on all the vertical loads applied on the formwork system like the
concrete weight, live load, and formwork load. However, horizontal loads are not automatically
checked in the model, and they have to be entered by the model user according to the
specifications of the formwork company manufacturing the system. In other words, the user of
the model has to input the number of shores to be braced together, and the number of rows that
should be braced.
10
1.7 Thesis Organization
This thesis is formed of Six Chapters. Chapter 1 provides a general introduction about the model
developed in this research paper, and the types of formwork considered in the research, and the
importance of appropriate formwork selection and formwork design optimization for a certain
project, and the problem statement ending with the research objectives, and methodology.
Chapter 2 discusses the types of horizontal formwork, and formwork design. Chapter 3 presents
the attempts that were done to optimize the design of formwork, the formwork selection system
produced previously, the economics of formwork, and the optimization system used. Chapter 4
discusses in details the model development, the formwork design procedures, the quantity takeoff procedures for each formwork system, the cost estimation of each system, and the parameters
on which the system is selected is going to be discussed and shown. Chapter 5 presents several
case studies where the developed model is verified and validated. Chapter 6 summarizes and
concludes the research and provides recommendations for future research in the formwork
selection system. The thesis structure is summarized in figure 6
General
Introduction
Importance of
Formwork Selection
& Design
Optimization
Chapter 1 (Introduction)
Problem Statment
Research Objectives
Research
methdology
Reserach
Limitations
Chapter 2(Formwork Systems & Design)
Types of Horizontal Formwork Systems
Formwork Design
Chapter 3(Literature review)
Formwork Design Optimization
Formwork Selection System
Optimization Techniques
Formwork Economics
Chapter 4 (Model Development)
Background &
model
methdology
Formwork
Design
Quantity Takeoff
Cost
Estimation
optimization
Program
limitations
User input
User output
Chapter 5 (Model Validation & Application)
Formwork Design Validation
Secon Nile Tower Formwork
Selection (case study)
Quantity Take-off validation
low income housing Formwork
selection and Design
optimizaton
Chapter 6(Conclusion & Recommondations)
Summary & Conclusion
Research outcomes & Contributions
Figure 6: Thesis Organization
11
Recommendations
Chapter 2
Horizontal Formwork Systems & Design
12
2 Chapter 2: Horizontal Formwork Systems & Design
2.1 Horizontal Formwork Systems
According to Hanna (1999), Horizontal Formwork systems can be classified into seven main
categories as shown in figure 7, which are Conventional wood system, which is also known as
Stick system, the Conventional Metal (aluminum) system, which is also known as improved
stick system), the Flying Formwork system, the column mounted shoring system, tunnel forming
system, joist-slab forming system, and the dome forming system
Conventional
Wood
Conventional Metal (alminum)
Hand-Set
Systems
Joist-slab
forming
Horziontal
Formwork
systems
dome forming
Flying Formwork
Crane-set
Systems
Column-mounted shoring
Tunnel Forming
Figure 7: Horizontal Formwork Systems classification (Hanna ,1999)
2.1.1 Conventional Wood system
As discussed before, conventional wood formwork systems, is simply composed of sheathing
which is supported by the joists, which transfers its loads to the shores through the main beam
which is called the stringer. All the components of this system are made out of wood (lumber)
and this system is considered one of the first formwork systems that have been made and used.
2.1.2 Conventional Metal (aluminum) system
The concept of the conventional metal system is the same as the conventional wood system;
however, the main difference is the type of material used; especially in the shores. According to
Hanna (1999) The Metal system can be formed of a wood joist, and a metal stringer, and an
aluminum prop, and it can be formed of a metal joist and stringer and steel frame. Now a days,
there are many systems for conventional Metal systems as the Props system, Frame systems, and
cuplock system discussed in this research paper.
13
2.1.3 Joist-Slab forming system
According to Hanna (1999), a one way joist slab is formed of regularly spaced joists arranged in
one direction and a thin cast in place slabs as the one shown in figure 8A The one way joist slabs
is formed by a steel pans, that is supported by a secondary beam called support member, this
support member is supported on a main beam that transfer the load to the shoring system as
shown in figure 8B.
B
A
Figure 8: One-Way joist slab system (http://www.whatsontheare.com/wp-content/uploads/2012/02/structural-systemspan-joist-concrete-decking-system-2.jpg)
2.1.4 Dome forming system
Standard Size domes are used for waffle slab construction Robert L. Peurifoy, and Garold D.
Oberlender (2011). The formwork system can be composed of a traditional wood or metal
formwork system, while the sheathing is composed of standard size domes as shown in figure 9
Figure 9: Dome forming system for waffle slab (http://red-form.com/assets/images/plastic-sky/sky2.png)
14
2.1.5 Flying formwork system
The flying formwork is also known as table formwork, Peurifoy, and Oberlender (2011)
described one of the first flying formworks that was produced, and this formwork was composed
of Sheathing Panels, which is made either of plywood or plyform, which are supported by
Aluminum Joist “Nailers” that can be a I-shaped beam or symmetrically designed joists with
wide top and bottom flanges. The aluminum joists are supported by an Aluminum Truss, which
has a telescoping extension legs that transfers the load to the ground and allow for leveling the
formwork, and for lowering during stripping. The previously mentioned components are shown
in figure 10
Figure 10: Truss Flying Form components (Hanna ,1999)
The basic idea of flying formwork is to reduce the time to strip the formwork, and install it in
another floor. In other words, instead of stripping the formwork, the formwork is lowered, and
moved to the upper floor by a crane, without the need to disassemble the formwork at the lower
level, and reassemble it again in the upper level. The truss Flying formwork cycle is shown in
Figure 11
Figure 11: Flying Formwork cycle (Hanna ,1999)
15
Currently, there are many table formwork systems that are being produced by different formwork
companies, with a much simpler cycle than that mentioned by Peurifoy and Oberlender (2011).
One of these table formwork systems is the one produced by Doka (2016), which is called
Dokamatic. This system simply consists of joists and stringers that can be aluminum, wood, or
metal, and Aluminum shores, and it has the same components of the props system, which has the
Doka-flex commercial name in doka. The lifting procedure of the dokamatic is very simple as it
is described in Figure 12
(1)Concrete
desired strength
fullfiled
(2)Lower the
system 5 cm from
the steel prop
(3) Place the
Dokart plus
beneth the
middle of the
table
(4)lower the
table on the
Dokart plus and
push up the floor
props
(5)Move the
table form to the
next floor by a CFork or a Table
lifting system
Figure 12: Dokamatic cycle (Doka,2016)
The Dokamatic system is lowered using the screw in the prop, which is lowered until it reaches
the Dokart plus as shown in figure 13, and then the table formwork is moved to the next floor,
either using a crane by the C-fork shown in figure 14 which holds the table, and lifts it to the
next floor or using a Table Lifting System(TLS) shown in figure 15, that lifts the table form
without the need for crane assistance
Figure 13: Lowering the steel prop in Dokamatic system (Doka ,2016)
16
Figure 14: C-Fork for Dokamatic System (Doka 2016)
Figure 15: TLS system for Dokamatic formwork (Doka ,2016)
2.1.6 Column Mounted Shoring system
According to Hanna (1999) the system consists of two major components (Shown in figure 16)
which are a deck panel and a column or wall mounted bracket jack system. The deck panel
consists of a plywood sheathing supported by a system of wood joist and a nailer type open web
stringer to allow the wood section to be inserted into the open web. Both the joists and the
stringers are supported by a truss system steel I beams that run on all the sides of the deck panel.
The I-beam rests on the column mounted jacks bolted in the concrete columns; therefore there
are no shores required as shown in figure 17
Figure 17: Column mounted shoring system
(http://journalofcommerce.com/Resizes/photoplayergallery/PageFiles/
12/51/15112/003_RBI-image-1007001.jpeg)
Figure 16: Components of column mounted shoring system
(Hanna,1999)
The Column mounted shoring cycle is done as follows:
The deck panel is assembled either on site or in an adjacent fabrication factory. The assembling
starts by bolting the trusses to the flange of the I-beam and then the wood joists are placed and
17
attached to the truss. Then, the elevation of the deck panel is marked on the face of the column or
the wall. Then the deck panel is lifted by a crane and positioned on the bracket jack system
already fixed in the concrete columns or walls by bolts, the deck panel is lowered to the
previously marked elevation and then rests on the bracket jack system. After the concrete has
been placed, and gained enough strength to support its own weight the stripping starts by
lowering the deck panel for the jacking system using adjustable screws, then the system is pulled
out by a crane, and moved to the next floor (Hanna, 1999)
2.1.7 Tunnel Formwork system
According to Hanna (1999) tunnel formwork systems is mainly used where the building has
many rooms, and modules that are repeated many times. Tunnel formwork reduces the
construction time of a building hugely, since both the vertical and horizontal elements are poured
together at the same time. A tunnel formwork system is composed as shown in figure 18 of deck
panel, which is a thick steel skin used to form the ceiling, and a wall panel, which is also a thick
steel skin, used to form the walls between two adjacent modules; also, one of the most
components of a tunnel formwork system is the waler and the waler splices which is used to
create a stiffer deck and wall panels so as to minimize the deflection due to the concrete lateral
pressure, in addition; a diagonal strut assembly is used to provide additional support for the floor
slab and keep the wall and the floor perpendicular to each other. A taper tie (Wall tie) must be
used between the forms of two adjacent tunnels in order to keep the forms in place while the
concrete is being placed, and a wheel jack assembly is installed to allow the laborers to move
tunnel forms over short distances in order to be pulled by a crane.
Figure 18: Components of Tunnel formwork system (Hanna,1999)
18
2.1.8 Comparison between different Horizontal Formwork system
Table 1 shows a comparison between the different types of formwork discussed earlier in this
section, and it is based on Hanna (1999) advantages and disadvantage of each formwork system
Table 1: Comparison between different Horizontal formwork systems -based on Hanna (1999)
Points of
Comparison
Labor cost
Conventional
Wood Formwork
High cost (labor
intensive system)
Conventional
Metal Formwork
Medium cost (Lower
than Conventional
wood formwork (20
to 30 percent
reduction)
Waste
High
Lower than
conventional wood
formwork
Number of reuses
Very Limited
Medium
Spans
limited
Flexibility
Very High
Large spans due to
the light weight of its
components and
improved capacity
Very High
Purchase Cost
Low purchase cost
Medium purchase
cost
Productivity
Very High
High
Low
Low
Crane
Dependency
Low
Low
High (Unless a TLS
system is used)
Very High
In windy days, lifting
the formwork
becomes very
difficult
Needs adequate
crane service in
terms of adequate
carrying capacity at
maximum and
minimum radii, and
adequate space
around the building
being constructed
Limitations
19
Flying Formwork
Low labor cost;
especially that the
formwork is
assembled once, and
labors needed for
stripping and
reinstallation is
severely reduced
Low, since
assembling and
stripping is not
required
High
Large spans due to
the light weight of its
components and
improved capacity
Medium (especially
when drop panel
exists or the building
does not have many
modules)
High purchase cost
Column Mounted
Formwork
High (Nearly the
same as conventional
wood formwork)
Very low
Very High, only the
plywood needs to be
changed
Large Spans, and a
height independent
system
Medium (especially
when drop panel
exists or the building
does not have many
modules)
Very High Purchase
cost
Tunnel
Formwork
High (the labor cost
can be reduced if an
experienced
foreman is hired,
since he can turn
unskilled labor into
skilled tunnel
operators)
Low
High
Medium Spans, and
the height should
not be more than
3.04 meters
High when several
modules for rooms
are available
The Highest
Purchase cost in all
horizontal
formwork systems
Very Low (Slabs
and walls are
poured together)
High
Requires modular
design for rooms to
be productive
2.1.9 New formwork system introduced in the market
Recently, there are several types of new formwork that is introduced rather than the formwork
systems categories explained before. The most two famous systems used nowadays, and was not
discussed by Hanna (1999) is the panel based formwork systems like the Sky Deck System
developed by Peri, and the Alu Deck system developed by Acorw, and the Dokadek 30
developed by Doka; these systems are simply composed of panels and props as shown in figure
19. The other type of formwork system newly introduced is the system with a main truss-shape
girder beam, and infill secondary beam that is installed between the main beams, and a vertical
prop or jack with a drop head installed on it is used as shown in figure 20, Acrow has a drop
head that can be installed to the shorebrace, and cuplock system, the benefit of the formwork
system with drop head is that it can be used for early striking formwork purposes
Figure 19: Panel Formwork System Example-Sky deck
system by Peri (Peri,2016)
Figure 20: Early Striking formwork system-Acrow
example (Acrow,2016)
2.2 Formwork Design
There are many researchers like Hanna (1999), M.K.Hurd (2005), and Rebort L. Peurifoy &
Garlod D. Oberlender (2011) that have investigated Slab Formwork Design throughout published
books, and all of them follow the same concept of formwork design; however, most of their
design equations are based on SI units, and since the model is developed using metric units, that
is why the following design equations will be based S.N.Nunnally (2007) who developed
equation for Formwork Design based on metric units as follows:
20
2.2.1 Formwork Design equations, where the spans between members are the output
2.2.1.1 Bending
A-One Span
36.5
𝐿=
1000
𝑑(
C-Three Spans or more
B-Two Span
𝐹𝑏 𝑏 1
)
2
𝑤
Eq. (1)
𝐿=
36.5
1000
𝑑(
𝐹𝑏 𝑏 1
𝑤
)
2
Eq. (2)
𝐿=
40.7
1000
𝑑(
𝐹𝑏 𝑏 1
𝑤
)2
Eq. (3)
2.2.1.2 Shear
A-One Span
1.34 𝐹𝑣 𝐴
𝐿=
1000 𝑤
B-Two Span
+ 2𝑑 Eq. (4)
𝐿=
1.07 𝐹𝑣 𝐴
1000 𝑤
C-Three Spans or more
+ 2𝑑
Eq. (5)
𝐿=
1.11 𝐹𝑣 𝐴
1000 𝑤
+ 2𝑑 Eq. (6)
2.2.1.3 Deflection
A-One Span
526
𝐿=
1000
(
B-Two Span
𝐸𝐼∆ 1
𝑤
)
4
Eq. (7)
Eq. (4)
𝑃
1000
(
𝐸𝐼∆ 1
Eq. (10)
2.2.1.5 Load
CW = 𝛾𝑐 * ts
Eq. (11)
DL= CW+FW+LL
Eq. (12)
JW= DL* Sj
Eq. (13)
SW= DL* Ss
Eq. (14)
PW=DL* Ap
Eq. (14’)
2.2.1.6 Bearing Capacity
Ab= (bje*dje)
𝑃
Fci=𝐴
𝑏
𝑤
)
Eq. (4)
2.2.1.4 Shore
𝑠
L= 𝑃𝑊
𝐿=
655
C-Three Spans or more
Eq. (15)
Eq. (16)
21
4
Eq. (8)
𝐿=
617
1000
(
𝐸𝐼∆ 1
𝑤
)4
Eq. (4)
Eq. (9)
2.2.1.7 Design procedures
According to Hanna (1999) Six Steps must be followed so as to have a safe formwork design,
and these steps are as follows:
1- Determine the total unit load on the floor decking, including the effect of impact, if any
2- Select the type of floor decking along with its net thickness
3- Determine the safe spacing of floor joists, based on the strength or permissible deflection of
the decking
4- Select the floor joists considering the load, type, size, and length of the joists
5- Select the type, size, and lengths of stringers, if required to support the joist
6- Select the type, size, length and safe spacing of shores considering the load, the strength of
stringers, and the safe capacity of the shores.
2.2.2 Formwork Design equation for stresses calculation
The previously mentioned design method is the design method followed in the majority of
formwork design books, since, in the model developed in this paper, the span between different
formwork elements must be a variable, and variables cannot be optimized if they are in a form of
equation; therefore, the equations had to be modified in the sense that the span is a variable
rather than an output. The following equations was developed by Arch Alexander (2003) and
they are simply the design equation for any beam with different supporting conditions
2.2.2.1 Bending
A-One Span
𝑀=
𝑤𝑙 2
8
B-Two Spans
Eq. (17)
2.2.2.2 Shear
Eq. (1)
A-One Span
𝑉=
𝑊𝑙
2
Eq. (1)
𝑀=
𝑤𝑙 2
C-Three Spans or more
Eq. (18)
9
Eq. (1)
B-Two Spans
Eq. (20)
𝑉 = 0.6𝑤𝑙
Eq. (1)
𝑀=
𝑤𝑙 2
Eq. (19)
Eq. (1)
C-Three Spans or more
Eq. (21)
𝑉 = 0.6𝑤𝑙
Eq. (1)
22
10
Eq. (22)
2.2.2.3 Deflection
A-One Span
∆𝑚𝑎𝑥 =
5𝑤𝑙 4
384𝐸𝐼
B-Two Spans
Eq. (23)
∆𝑚𝑎𝑥 =
𝑤𝑙 4
185𝐸𝐼
Eq. (1)Requirements to have a safe design
Eq. (1)
2.2.2.4
𝑀
S=
𝐹𝑏
C-Three Spans or more
Eq. (24)
∆𝑚𝑎𝑥 =
𝑤𝑙 4
145𝐸𝐼
Eq. (1)
Eq. (26)
For the member to be safe in bending the Section modulus of the element must be equal to the
Section modulus calculated by equation 26
For the member to be safe in Shear, the Shear force calculated from any of Equation 20,21,22
must be less than the Shear Capacity (Fv) of the element
For the member to be safe in deflection, the deflection calculated by equation 23,24,and 25 must
not exceed the maximum deflection specified by the user
23
Eq. (25)
Chapter 3
Literature review
24
3 Chapter 3 literature review
3.1 Formwork Design Optimization
Hanna and Senouci (1995) developed one of the first design optimization models for
conventional wood formwork system, which modified the design process of the formwork from
just being concerned with the safety of the formwork system, and the spacing between its
different elements, to a process that considers the material and labor cost, and recalculate the
spans so as to minimize the cost of the system. As it is shown from figure 23, the traditional
design approach just considers the spans between different elements in the conventional wood
formwork system; however, the developed algorithm by Hanna and Senouci (1995) as shown in
Figure 22 considers varying the distances between the joists until the sheathing cost is
minimized, this process is repeated throughout the design of all the formwork elements, until an
optimized design is reached. One important aspect that Hanna and Senouci (1995) highlighted is
that designing the formwork members to the maximum span that they can reach safely does not
always result in a lower cost design. As it shown in Figure 21, the cost of the formwork begins to
increase after the joist spacing exceeded 16 inch, since after this spacing is exceeded more
stringers and shores needed to be added so as to support the joist; therefore, the cost of the
formwork system increased.
Figure 21: Joist Spacing versus formwork cost (Hanna and Senouci,1995)
25
Figure 22: Optimized Slab Formwork Design Flow Chart (Hanna and
Senouci,1995)
Figure 23: Conventional Slab Formwork Design flow Chart
(Hanna and Senouci,1995)
The user interface developed by Hanna and Senouci(1995) was very simple, and all the data can
be inputted in a user friendly way. Finally, in their research Hanna and Senouci (1995) stated that
they have tried their program on several available wood materials in different projects and the
model successfully did a cost savings from 9.9% to 29% for the formwork system. No doubt, the
model developed by Hanna and Senouci (1995) is considered a very good model for formwork
design optimization for conventional wood formwork system; however, the model did not
26
consider the different lengths of the joist, and stringer, and the direction of the stringer, and the
joist, which are still variables that affect the formwork cost. In other words, Hanna and Senouci
(1995) succeeded into providing users with economic formwork design combinations; however,
they still did not provide the users with data related to the project they are working in like the
length of the joist, and stringer and the direction of each of them that will yield to the least cost
for the wood formwork used. Also, the model developed cannot work properly for other systems
rather than Conventional wood formwork, since the variables of such systems are much more
than that of wood formwork; however, the concept they used can be the basis for a program that
can optimize different formwork systems.
A very interesting model developed was the dynamic programming concept that Antony
D. Radford and John S.Gero (1988) did approach in what they called the shortest route problem.
These researchers started their model by giving a validated statement that the distance between
joists depends on the plywood, and the distance between the stringers, depends mainly on the
joists and the plywood, and finally the distance between the shores depends mainly on the
stringers. Their definition of the spans for each formwork elements were as follows:
1-the choice of sheet thickness depends on sheet span (X1)
2- The choice of joist size depends on joist spacing, X1, and joist span,X2
3- The choice of bearer size depends on bearer spacing, X2, and bearer span, X3
4-The number of props also depends on X2 and X3
They also stated that if there are 3 span options for X1 and 6 Span options for X2 and 7 span
options for X3, this will total to 3*6*7= 126 possible combinations. So as to decrease such
combination Radford and Gero (1998) stated that since the total cost of the system is based on
the cost of each of its components, so minimizing the cost of each component will yield to the
least possible cost for the system as a whole. They developed a flow chart, shown in figure 24,
that can be the basis for a programming code. The main concept is to first optimize the joist span,
by choosing the least cost Sheathing-joist combination, and after doing so this cheapest
combination is used to design the stringers, and the shores; thus decrease the number of possible
combination to (3*6)+(6*7)= 60 combinations, consequently reach the optimum design in a
quicker, and less complicated way.
27
Figure 24: Dynamic Programming flowchart for Formwork Design Optimization (Radford and Gero ,1988)
Despite the fact that the dynamic programming concept represented by Radford, and Gero (1988)
is very interesting; however, when there is several options for the stringers material, it might not
work that accurately, because they first calculate the span of the joist based on the least possible
cost for the plywood and the joist combination, and after they do so, they start optimizing the
span of the stringer using the same concept. This will not yield to the least cost effective design,
since the cheapest joist could require a certain beam for the stringer that is much more expensive
than having a lower span for the joist, with a cheaper material stringer. This was clearly shown in
figure 21, where the system cost increased after a certain joist span, since more expensive
stringer and shores were needed (Hanna and Senouci, 1995); therefore, dynamic programming is
a very promising method to use in formwork design optimization; however, slight modifications
needs to be done on Radford,and Gero (1988) dynamic programming concept.
28
3.2 Formwork Selection System
3.2.1 Expert based systems
One of the first knowledge based system developed was done by Awad Hanna in two
research papers the first paper was developed by Awad Hanna (1989) in his PHD research, and
the second paper developed by Awad Hanna, Jack Willenbrock, and Victor Sanvido (1992). No
doubt, the model is considered one of the first attempts to formwork selection system using ifthen based rules. The researchers used EXSYS Professional shell in developing their model that
was based on three phases which are shown in figure 25, which are familiarization, elicitation,
and organization and representation. The familiarization phase include a combination of
published literature and unstructured interview with several experts in the construction industry;
so as to be able to understand the variables behind the selection, and be able to develop a
questionnaires for the next step. Then, the elicitation stage include structured interviews, and
questionnaires with different experts. Finally, in the last stage which is organization and
representation, the interview results are recorded, and categorized. These results are loaded into
the shell directly in the form of if-then rules. The system asks the user for inputs in a multiplechoice format, and uses these inputs to make inferences and reach conclusions. At the end of
each run, each system displays the selected type of formwork followed by probability from zero
to 10 as shown in figure 26, which indicates the confidence level in the selected system (Hanna
et al.,1992).
Figure 25: Formwork Knowledge acquisition system procedures (Hanna,Willenbrock, and Sanvido ,1992)
29
Figure 26: Example of formwork Knowledge Based model output (Hanna, Willenbrock and Sanvido,1992)
The knowledge acquisition system developed by Hanna, et al.(1992) has a very detailed
database; however, it lacks any optimization feature, and not only does it depends on experts in
the field assumptions, but it specifies the formwork system applicable for the project based on a
confidence interval, which reflects uncertainty for decision makers; especially in an important
aspect like formwork selection. Moreover, Hanna, et al. (1992) stated that some of the sources of
error in their database collection were inaccessibility to cost data, expert’s conflict in opinion,
which are two factors that affect the outputted decision of which formwork system to use.
30
One of the most successful formwork selection systems was developed by Emad
ElBeltagi, et al. (2011) in which they developed a fuzzy logic model that helps project decision
makers in selecting the formwork system suitable for their projects. The systems they used in
their model were conventional wooden formwork system, S-beam and props/shore-brace system,
Telescopic beam and props/shore-brace system; early striking panel (drop head) system, Table
form, and Multi-flex . Elbeltagi et al. (2011) started by investigating what are the factors
affecting the selection of a formwork system, and they concluded based on experts opinion that
the major five factors affecting the selection of a formwork in Egypt are speed of construction,
hoisting equipment, available capital , slab type, and area of practice; using these five factors,
and several questioners as shown in figure 27, they were able to get the ranking of each
formwork system based on the five factors investigated in the model. In order to develop a fuzzy
logic model, First, the low, medium, and high ranges for each factor out of the five factors and
the output decision is inputted to the fuzzy logic program as shown in figure 29, after doing so
they were able to calculate a score for each system based on the inputted data, the Low factor is
assigned a value of one, and the Medium factor is assigned a value of two, and the High factor is
assigned a value of three. Elbeltagi et al. (2011) tried their model successfully on several projects
as shown in figure 28, and they distributed a questionnaires on several formwork experts in
Egypt, in which they stated their opinion about the model as shown in figure 30.
Figure 27: Formwork selection system questioner output (Elbeltagi et al. ,2011)
Figure 28: Output of Fuzzy logic model for formwork selection (Elbeltagi et al. ,2011)
31
Figure 29: Fuzzy logic variables and output ranges for formwork selection system (Elbeltagi et al. ,2011)
Figure 30: System validation questioner (Elbeltagi et al. ,2011)
Although the model developed by Elbeltagi et. Al (2011) is considered a success as it is shown
from the questionnaire; however, the lowest points that the model got from the questioner was
relevance of inputs, accuracy of results, usefulness, and overall performance. This shows that
despite the fact that the model did cover several important factors for selecting a formwork
system in Egypt, but it still lacked a method by which the user can validate the output, and obtain
a purchase cost, and design for the selected systems.This is the problem with expert based
systems as it is going to be shown throughout this literature review.
Yoonseok Shin, et.al. (2012), presented a model that outputs which formwork method to
use based on a boosted decision tree model. First, they began by identifying the types of
horizontal formwork used in Korea, which is the country of interest in their research; the types of
horizontal formwork systems they used were wood forms, Con-panel, Aluminum forms, table
forms, and Sky-deck. Moreover, Shin et al. (2012), did a research for experts in the construction
32
field industry, and as shown in figure 31, they identified the factors that affect the selection of
formwork which are structural type, building height, number of floors, area of typical floor per
zone, building shape, typical floor cycle, and degree of repetition, and they gave ranges for
which each type of horizontal formwork is applicable for usage.
Figure 31: Factors affecting horizontal formwork selection (Shin et al.,2012)
After doing so, Shin et. al (2012) tried to use an improved type of decision tree, which is called
boosted decision tree, the basic difference between decision tree, and boosted decision tree, is
how the decision tree comes up with the decision. In a regular decision tree models, as shown in
figure 33, the model first starts up at the highest level node, and then goes to another level using
a yes or no answer; however, this is not accurate, since any minor fluctuation in the data inputted
to the decision tree, will affect the final decision outputted from the tree(Shin et. al,2012).
Therefore, they decided to use boosted decision tree, which as shown in figure 32, that considers
the experts opinion inputted to the data base, by assigning weights to every decision made;
therefore, instead of having a Yes or No answer at each node. A weight is developed while each
decision is taken, and the decision outputted will have a confidence level as the one shown in
figure 34. Shin et. al (2012) have tried their model over several cases, and they concluded that
the boosted decision trees method used gives more accurate results than normal decision tree
models, and neural network models.
33
Figure 33: Decision Tree Concept in formwork selection system
(Shin et al.,2012)
Figure 32: Boosted Decision tree concept in formwork
selection system (Shin et.al.,2012)
Figure 34: Boosted decision tree output for formwork selection system with confidence level (Shin et.al. 2012)
The model developed by Shin et al (2012) indeed works as it is shown in their case studies
section; however, using boosted decision trees to decide upon which formwork system to use, is
not accurate, and will depend mainly on experts judgment concerning the factors affecting such a
selection. They clearly made this statement in their research; however, they stated that it would
be hard to depend on models that are not expert based system, due to the many variables
involved in the selection criteria. The formwork system to use for a certain project mainly
depends on the nature of this project. In other words, two projects might have the same nature,
but with a slightly different detail like having a cantilever slab, or far away location for example,
that can greatly affect the location. In brief, Shin et al. (2012) model will output an initial
decision concerning which formwork system to use, and this decision will mainly depend on
formwork experts opinions, which might give inaccurate opinions, and Shin et al. (2012) stated
that some inaccuracy in their model might take place due to inaccurate experts opinion.
34
3.2.2 Optimization based systems
The model developed by Taehoon Kim et al. (2012), represents a narrower look to the
formwork selection optimization problem in construction project. The researchers began by
proposing a new formwork system, that they called Flexible table form (FTF). The components
of this form is shown in figure 35. In fact, the basic idea of this formwork system, is that it must
be assembled in a rectangular shape using certain modules.
Figure 35: Flexible Table form components (Kim et al., 2012)
The basic idea is to cover all the slab formwork using standard units, and minimize the usage of
special units, or what they called subunits with adjustment; the applicators starts by drawing the
structure using available areas, and non-available areas concept. In which available areas are the
areas where there should be a formwork, and non-available areas are areas that are outside the
boundaries of the building or area inside core or a column. This concept is shown in figure 36 in
which the available, non-available areas, standard and non-standard FTF are identified.
Figure 36: Geometry of the available and unavailable areas, units, and subunits (Kim et al.,2012)
35
Kim et al.(2012) depended on a mathematical model that is solved using a program called
CPLEX, and the model has two optimization objectives. These optimization objectives are
minimizing the remaining area that is covered by non-standard FTF panels, and minimizing the
formwork arrays or in other words, increasing the alignment of the formwork so as to allow for
more organized workspace below the formwork area. Moreover, in order for the model to solve
any irregular shape building it begins by dividing the building into regions, and each region is
designed separately as shown in figure 38; in addition, figure 37 shows the outputted formwork
optimized layout for the project used in the case study.
Figure 38: The formwork layout divided into
regions (Kim et al.,2012)
Figure 37: Optimized formwork design layout
(Kim et al.,2012)
The model developed by Kim et al.(2012) considers the geometry of the building, and the
available workspace; however, it ignores several factors that affects formwork selection, and
such as crane availability. Also, it depends mainly on one type of horizontal formwork system,
which they called the Flexible table form. Although Kim et al. (2012) developed a very
beneficial formwork selection system; especially that the selection was done without the need for
expert opinions; therefore, yield more accurate results, still their model needs to be adjusted to
include other formwork systems than the flexible table form.
Rather than thinking of formulating a model that optimizes many formwork systems,
some researchers try to optimize the formwork used for a certain construction phenomena. One
of these models is the one developed by Khaled Nassar, and Ebrahim Aly (2012), which was
36
concerned with optimizing formwork for complex free form shell structures like the building
shapes shown in figure 39.
Figure 39: Free form shell structures (Nassar and Aly ,2012)
Nassar & Aly (2012) in their model used Rhino as the modeling software to draw the structure,
and used an input inside Rhino that uses Genetic algorithms for optimization. The objective of
the model was to balance the shape discrepancy, cost, and effort used to trim the plywood and
this is down through the following equation:
w1 (
𝑐−𝐶 ′
𝐶′
𝑠−𝑠′
) + w2 (
𝑠′
)+ w3(
𝐷−𝐷 ′
𝐷′
),
Where w1 is the weight of the cost element for the user. C is the cost of the formwork, and C’ is the
minimum cost that can be achieved when neglecting other terms.
w2 is the weight of the effort element for the user, S is minimum effort that can be achieved when
neglecting the other terms
w3 is the weight of the discrepancy element for the user, D is the discrepancy (summation of areas
between the curve and the approximated line segments and D’ is the minimum discrepancy that can be
achieved when neglecting the other terms
The variables are the length of the plywood panels, width and depth of both the stringer, and the
joist, while the constraints are to not to exceed the bending, shear, and deflection capacity of
used formwork elements. Using this concept, they were able to try their model successfully to an
existing project which 3d model is shown in figure 40.
Figure 40 Free form structure (Nassar and Aly ,2012)
37
The model was used for different cost, shape, and effort weights, and the formwork design for
each case was inputted as shown in figure 41.
Figure 41: Model optimization output (Nassar and Aly , 2012)
Nassar & Aly (2012) model did a successful job in producing an optimized formwork design for
free form structure; however their model is just concerned with a certain type of structures, and
is not tailored to account for formwork system alternatives, since it is mainly related to free form
structures.
3.3 Formwork Economics
Robert. L. Peurifoy, et al. (2006) presented an accurate cost model that should be considered in
order to select a formwork system.
3.3.1 Material cost
The equation developed by Peurifoy et al. (2006) to calculate the purchase or rental cost of
formwork is as follows:
Cf=
n=N/Ny
Eq. (28)
𝑃𝑓 ∗𝑈𝑆𝐶𝑅𝐹(𝑛,𝑖)−𝐿𝑛 ∗𝑈𝑆𝑆𝐹𝐹(𝑛,𝑖)
USCFR (n,i)=
𝑁𝑦
𝑖(1+𝑖)𝑛
(1+𝑖)𝑛 −1
Eq. (29)
Eq. (27)
USSFF(n,i)=
𝑖
(1+𝑖)𝑛 −1
Eq. (30)
If N<=Ny which means that the useful life of the element is less than 1 year (Commonly for
lumber elements) the cost of purchase or rental is calculated as follows:
𝑃𝑓
Cf=
𝑁
Eq. (31)
The best aspect in the equation developed by Peurifoy et al. (2006) is that it considers the useful
life of the element, and the number of times it is going to be used per year in the project, and this
aspect inputs a very important factor which is the number of uses for the element till disposal,
38
which is always a factor that is overlooked while selecting a formwork system. For example, if
the useful life of lumber versus aluminum element is not considered while calculating the
purchase cost, the lumber will always be economical, since its purchase cost is much lower than
that of aluminum; however, aluminum has more than four times the life time of lumber, using
Peurifoy et al. (2006) equation this factor is considered.
3.3.2 Maintenance cost
According to Peurifoy et al. (2006) long lasting steel elements, and to a lesser extent aluminum
elements, require periodic routine repair/maintenance (e.g. paintwork, welding, correcting the
shape and flatness of metal surfaces that have irregularities), and that expense should be added to
the material cost using the following equations:
𝑇𝑚 ∗𝑈𝑆𝑆𝐹𝐹(𝑓,𝑖)
Cm=
USSFF=
𝑁𝑦
𝑖
(1+𝑖)𝑓 −1
Eq. (32)
Eq.(33)
3.3.3 Modification cost
According to Peurifoy et al. (2006) forming systems may undergo modification, from minor
alterations to major reconfiguration, to adjust them to their next round of reuse on another
project. In this case, modification cost may be calculated using the following equations:
𝑅∗𝑃𝑊𝐶𝐴𝐹(𝑘,𝑖)∗𝑈𝑆𝐶𝑅𝐹(𝑛,𝑖)
CR=
PWCAF(k,i)=
𝑁𝑦
1
(1+𝑖)𝑘
Eq. (34)
Eq.(35)
3.4 Optimization Technique
There are many methods that can be used to develop a formwork selection system, and design
optimization like what was discussed in the preceding sections of the literature review. These
methods are such as Dynamic programming, Fuzzy logic, Neural networks, and evolutionary
algorithms; however, fuzzy logic, and neural networks needs an expert based system, in which
there is a database in order to be used in the optimization modeling, and Dynamic programming
needs a great deal of complex algorithm in order to be able to function properly; therefore, that
39
leads us to a very popular optimization technique called Evolutionary algorithms which is
composed of several algorithms like memetic algorithms, Particle swarm, Ant colony, Shuffled
Frog leaping, and many other techniques. However, Genetic algorithm is the type of evolutionary
algorithm that is going to be used in the model developed in this research paper due to the
following reasons:
1-Genetic algorithms has been applied successfully on several applications in different industries
(Blickle ,1967). Also, as stated by Mujahid Tabassum and Kuruvilla Mathew (2014), Genetic
algorithms has been applied on different applications like robotics, data encryption, computer
gaming, and engineering design. The model developed in this paper falls under the category of
engineering design. Using genetic algorithms in designing a new engineering model is a complex
and time consuming process, but designing an optimal model which uses the minimum resources
to deliver the maximum output is even much complex. Such a task requires great deal of effort
and experience to be completed perfectly. This is where one more time the functionality of
Genetic algorithm comes into action, since it can be integrated into computer based engineering
design applications. By following such a strategy the application will be able to analyze different
aspect of engineering design principles when generating a new design for a given problem. This
approach in addition to providing the required design will also assist the designers to identify the
frailties and possible failure points of the design. Such an approach is currently being used in
many engineering industries such as aerospace, civil, automotive, robotics, electronics,
mechatronics (Tabassum and Mathew,2014).
2- Genetic Algorithms are remarkably flexible and can be used to tackle a wide variety of
problems. In other words as stated by David Rutten (2010) “There are classes of problems which
are by definition beyond the reach of even the best solver implementation and other classes that
are very difficult to solve, but these are typically rare in the province of the human meso-world.
By and large the problems we encounter on a daily basis fall into the 'evolutionary solvable'
category”.
3-As stated by Rutten (2010), Genetic algorithms can be “forgiving”, since they chew on
problems that have been under or over constrained or otherwise poorly formulated
4-Genetic algorithms run-time is progressive (Rutten,2010). In other word, genetic algorithms
start from a random answer reaching a near optimum solution, and this gives the user the ability
to stop the optimization process, whenever his desired stopping criteria is met.
40
5- Genetic algorithms are suitable for search in complex work space. It is exceedingly difficult to
construct heuristics for complex combinatorial problems. In these problems the choice of one
variable may change the meaning or quality of another. This problem is solved when
evolutionary algorithms is used (Blickle ,1967).
3.4.1 Genetic algorithms
The Optimization technique used is one of the evolutionary algorithms methods, which is
Genetic algorithm, the basic concept of basic algorithm is the survival of the fittest, which is
based on the mechanics of natural selection and genetics, to search through the decision space for
optimal solutions (Chih-tsang Lin et al.,2012). Genetic algorithm works by using an initial
population, this population is formed out of chromosomes, these chromosomes are formed out of
genes, and these genes are the variables in the optimization problem, a fitness value is calculated
based on these variables, and the required objective function, which is the desired outcome of the
optimization. The population reproduces by what is called crossover or mutation, the crossover
takes place when several genes are exchanged between two chromosomes through a certain
cutting point, while mutation is simply done exchanging values between two chromosomes. In
Genetic algorithm, The Weakest parent (low fitness value) is replaced with the strongest child,
and this process is repeated until a near optimum solution is reached as shown in figure 42.
Figure 42: Genetic Algorithms structure (Chih-tsang Lin et.al ,2012).
41
A-Population
The process of genetic algorithms starts with a randomly created first generation of population.
Every individual in a generation (population) represents one solution and consists of one
chromosome with a number of genes; these genes are the variables of the optimization process as
shown in figure 43. Each chromosome is then evaluated for its fitness (The fitness simply means
that it gives a better solution towards the objective function. The more fitness the chromosomes
have the better its chance to survive to the next generation (Bryan Christopher Que,2002)( (A.
Haidar et al.,1999).
Figure 43: Chromosome in genetic algorithm (Que,2002)
B-Evolution Operators
1-Crossover: the crossover is simply the process of exchanging the genes between two parents
at a certain cutting points, in order to create two off-springs (A. Haidar et al.,1999).. In this
process, a random point(s) along the strings of two genes is selected at random and portions to
the one side of that point are exchanged between the genes to create a new gene as shown in
figure 44.
Figure 44: One Point Crossover in Genetic Algorithms (Piotr Jaśkowski and Anna Sobotka , 2006)
2-Mutation: Mutation is used to add new genetic (variables) to the gene pool. The mutation
takes place by exchanging genes values in the parent chromosome, in order to form an offspring.
Mutation alone generally does not advance the search for a solution but it does provide insurance
42
against the development of a uniform population incapable of further evolution; in other words it
prevents the algorithm from being struck in a local maximum or local minimum value in the
search space (A. Haidar et al.,1999). An Example of mutation is shown in figure 45.
Figure 45: Mutation Example in Genetic algorithms (Chih-tsang Lin et.al ,2012)
3- Concept:
The concept of Genetic algorithms is simply that there are a set of variables that affects a certain
output (Optimization goal), and there are a certain constraints that cannot be violated for the
solution to be valid, and finally there must be an objective function, which is the value that needs
to be optimized, whether to be minimized, maximize, or to be set to a certain value.
4-Disadvantages of Evolutionary algorithms:
According to Tobias Blickle (1967) the disadvantages of evolutionary algorithms are as follows:
4-1-High Computational demand: Evolutionary algorithms process slowly when it comes to
solving an optimization problem with enormous number of valid solutions; this is not a
shortcoming of the algorithm itself, but rather a limitation of the computing power available at
the time of running. Nowadays, problems become more and more complex and the number of
variables becomes excessive, thus requiring a considerable amount of computational and
processing powers.
4-2-Difficult adjustments of Parameters: A large number of parameters need to be adjusted,
for example the kind of selection and crossover operator to use, the population size, the
probabilities of applying a certain operator, and the form of the fitness function.
4-3-Heuristic Principle: sometimes if the rate of mutation is not considered the algorithm can
be stuck in a local minimum or maximum value, and therefore, the solution outputted can be a
near optimum solution; however, this might not be the most optimum solution, and this is one of
the strongest weakness of evolutionary algorithms.
43
Chapter 4
Model Formulation
44
4 Chapter 4: Model Formulation
4.1 Background and Model Methodology
The process followed currently for formwork system selection in most of the construction
companies in Egypt, based on two unstructured interviews with Planning Managers in two highrise projects in Egypt, who have over than 20 years of experience in the construction industry in
Egypt and Dubai, is as shown in figure 46. The decision of which formwork to use is based on
the cycle time, and the purchase cost of the system, which is obtained from formwork supplier,
who might have provided a purchase cost for a formwork system with an uneconomical design.
No doubt, The uncertainty concerning the economy of the formwork design provided by the
supplier, and the selection of the formwork based on the current Purchase cost, and the cycle
time, while disregarding other factor that are involved in formwork selection, will result to an
inaccurate decision concerning formwork selection in a project, and the problem becomes more
complicated when the selection is based on multiple projects.
Request Cost Quotation from Formwork
suppliers (at least three suppliers)
The Cheapest Formwork System that
fulfils the required cycle time for the
project is selected
Issue a Purchase order for the selected
system, and request Formwork Design
for this system
Figure 46: The current formwork selection process followed in Egypt
That is why the Formwork Selection system concept shown in figure 47 was developed in this
research to support decision makers in selecting the appropriate formwork system based on the
factors affecting formwork which was discussed in the introduction chapter. The Formwork
Selection system does not require any additional effort from the decision maker except inputting
the project data (Geometry, material related properties, and the cost data). In return the user gets
an optimized design, and purchase cost for the selected formwork system for the inputted project
45
Formwork Selection Model Proposed
Input Project Data:
Request Prices from Formwork
Suppliers for Selected
formwork system components
1- Project Geometry
2-Material Data
3-Cost Data
Formwork Design
for Each System
Automated Process
Quantity take-off for
each Formwork
system
Design
Optimization
In the Excel Model
Cost Estimation for
each Formwork
System (Considering
all factors affecting
Formwork
Selection)
Output
Most suitable
Formwork system
for the Project
Issue a Purchase
order for the
selected system
using the quantity
take-off sheet
Figure 47: Formwork Selection process followed in the formwork selection model
This chapter is divided into seven sections, the first section will discuss the formwork design for
each of the formwork components in details, second section will discuss the quantity take-off
procedures, and method. Moreover, the third section will discuss the cost estimation procedures;
the fourth section will discuss the optimization process. In addition, the fifth and the sixth two
sections will discuss the user input, and output in the model respectively. Finally, the last section
is going to discuss the research limitations.
46
4.2
Formwork Design
4.2.1 Design Concept
The Design Equations used in order to design the formwork components of the selected
formwork systems are starting from Equation 17 till Equation 26 developed by Alexander (2003)
as discussed in the horizontal formwork systems, and design chapter.
After conducting unstructured interviews with several contractors, Acrow Masr Formwork
designer, and based on the researcher own experience. The practice is that unified spacing is
provided for each slab thickness for each formwork component. In other words, the practice is
not to give a certain span for a formwork component like the stringer at different supporting
conditions, this will be hardly followed on site, and might lead to severe mistakes regarding the
spacing of the formwork elements. All the formwork design examples found in the literature
review assumed a three span or more beam for formwork design. Also, Acorw Masr Formwork
calculation sheets make this assumption for real-life projects. In order to, reach a solution that
would consider the practicality of construction, and the safety of the formwork. The model will
give the user two options to choose from while designing the formwork, the first option is to
make the design of formwork based on three spans or more beam supporting conditions or to
choose what is called conservative design, which will consider the maximum case in bending,
shear, and deflection for different supporting conditions, which are three spans or more for
bending, and one span for shear and deflection. The user of the model can reasonably assume a
three spans or more condition if he/she has reasonable spans between the vertical elements;
however, if there is a certain area in the inputted building that has narrow spans, the user can
choose the conservative design concept
4.2.1.1 Three Spans or more
For the three spans or more design concept the used equations for the bending, shear, and
deflection are as follows (Alexander,2003)
Bending
𝑀=
𝑤𝑙2
10
Shear
Eq. (19)
Deflection
𝑉 = 0.6𝑤𝑙
47
Eq.(22)
𝑤𝑙4
∆= 145𝐸𝐼
Eq.(25)
4.2.1.2Conservative
For the conservative design concept the used equations for the bending (one span), shear (Three
spans or more), and deflection (one span) are as follows (Alexander,2003)
Bending
𝑀=
𝑤𝑙2
8
Shear
Deflection
𝑉 = 0.6𝑤𝑙
Eq. (17)
Eq.(22)
5𝑤𝑙4
∆= 384𝐸𝐼
Eq.(23)
4.2.2 Loads
According to Hanna (1999) formwork is a temporary structure that must support the following
loads:
A- Weight of Concrete: The weight of ordinary concrete can be assumed to be 2.5 t/m3;
however this might vary if light weight concrete is used or any other of special type of concrete
and the weight of the concrete is calculated using equation 11 found in chapter 2
B- Weight of Formwork: Formwork must be able to support its own weight, the weight of each
component of the formwork system is always provided by the supplier. In the developed model,
the program automatically calculates the weight of the formwork per m2 based on the design
parameters
C- Live Load: According to ACI 347R-14, the minimum live load for formwork elements to be
designed for is 2.4KPa, and this value increase 3.6KPa When motorized carts are used. Since in
Egypt usually there are motorized viabrators used, the model will use a minimum 3.6 KPa;
however, if the user inputs a value more than 3.6KPa, the model will use the largest load while
calculating the live load.
Design Load: the Design load is simply the summation of the Weight of Concrete, Formwork
Weight, and Live loads. The Design Loads for different formwork are calculated using equation
12,13,14,14’ discussed in chapter 2
Horizontal Load: According to Nunnally (2007) the minimum lateral design load calculated
using Equation 36, and it should be at least equal to 1.46KN/m
H=0.02 * DL * ws
(Equation 36)
48
Table 2 shows an example for design load calculations done by the model
Table 2: Example from the model for Design Loads calculations
Distance Between Secondary beams
Distance Between Main Beam
Main Direction for Main Beam
Props Distance (X-direction)
Props Distance (Y-direction)
Slab Thickness
Dead load
Live Load (User input)
Live Load (Design)
Weight of formwork
Design Load
Total Load (For Sheathing)
Total Load (For Secondary Beam)
Total Load (For Main Beam) (X-direction)
Total Load (For Main Beam) (y-direction)
Total Load (Props Design)
Design parameters
0.45
m
1.2
m
X
0.90
m
1.20
m
Design Loads
0.45
m
1.13
t/m2
0.20
t/m2
0.36
t/m2
0.11
1.60
1.60
0.72
1.92
1.44
1.73
t/m2
t/m2
t/m
t/m
t/m
t/m
t
Calculated
User input
Calculated
Calculated
Calculated
Calculated
Calculated
Calculated
Calculated
Calculated
Equation 11
Minimum load ACI 347R14
Equation 12
Equation 12
Equation 13
Equation 14
Equation 14
Equation 14’
4.2.3 Sheathing
The sheathing material is designed as a slab. In slab the bending stress, and the deflection stress
are the governing stresses. In slabs, shear force is ignored due to the large surface area and the
small thickness compared to this area. Therefore, the sheathing is checked for the bending, and
the deflection
A-Bending : The bending stresses is calculated using either equation 17 or 19 depending on the
design concept; however in the equation the load used is the design load, and the Span used is
simply the distance between the Secondary Beams (Joists). For the bending to be safe, the
section modulus of the material has to be more than the section modulus calculated using
Equation 26
B-Deflection :The deflection is calculated using Either with equation 23 or 25 depending on the
design concept; however in the equation the Span used is simply the distance between the
Secondary Beams (Joists). For the deflection to be safe it has to be less than the maximum
deflection desired by the user.
49
C-Example: The following Example shown in table 3 is outputted from the model and it shows
the checks done for the sheathing design, the Design load used are based on the example shown
in table 2
Table 3: Sheathing Design checks from the Model
Sheathing Design checks outputted from the model
Moment
Assumed Distance between secondary beams
Moment On Plywood section
0.45 m
0.032 t.m
Moment On Plywood section
3.244 t.cm
Calculated Section Modulus (Z)
Section Modulus of Plywood
Safe
38.17 cm3
54 cm3
Equations used
Calculated (Three
spans or more
concept)
Calculated
(Conversion)
Calculated
User input
Equation 19
Equation 26
1
Deflection
Assumed Distance between secondary beams
Modulus of Elasticity
Moment of inertia
Load
Deflection
Allowable deflection for sheathing
Allowable deflection for sheathing
Safe
Equations used
45
56.4
48.6
0.016
0.166
0.167
1.67
cm
t/cm2
cm4
t/cm2
cm
cm
mm
User input
User input
User input
Equation 12
Equation 25
L/270
4.2.4 Secondary Beam (Joist)
The Secondary Beam must be checked against bending, shear, and deflection as follows:
A-Bending : The bending stresses is calculated using either equation 17 or 19 depending on the
design concept; however in the equation the load used is the joist (JW) load, and the Span used is
simply the distance between the Main Beams (Stringers). For the bending to be safe, the section
modulus of the material has to be more than the section modulus calculated using Equation 26
B-Shear : The Shear stresses is calculated using with equation 22; however in the equation the
load used is the joist (JW) load, and the Span used is simply the distance between the Main
Beams (Stringers). For the shear to be safe, the shear capacity of the material has to be more than
the shear force on the secondary beam
50
1
C-Deflection :The deflection is calculated using Either with equation 23 or 25 depending on the
design concept; however in the equation the Span used is simply the distance between the Main
Beams (Stringers). For the deflection to be safe it has to be less than the maximum deflection
desired by the user.
D-Example The following Example shown in table 4 shows the design checks made for the
secondary beam in the model, the Design load used are based on the example shown in table 2
Table 4: Secondary Beam Design checks outputted from the Model
Secondary Beam design checks outputted from the model
Equations used
Moment
Assumed Distance between Props(X-direction)
0.90 m
Assumed Distance between Props(Y-direction)
1.20 m
Moment On Secondary Beam
0.105 t.m
Moment On Secondary Beam
10.46 t.cm
Calculated Section Modulus (Z)
95.97 cm3
460 cm3
Section Modulus of Secondary Beam
Since, X is direction for Main beam, therefore
span of Secondary Beam is 1.2 (Y-direction
Span)
Calculated using Equation 19
Calculated using Equation 26
User input
1
Safe
Equations used
Shear
Assumed Distance between Props(X-direction)
0.90 m
Assumed Distance between Props(Y-direction)
1.20 m
Shear Force on Secondary Beam
0.52 t
Shear Capacity of Secondary Beam
1.10 t
Since, X is direction for Main beam, therefore
span of Secondary Beam is 1.2 (Y-direction
Span)
Calculated using Equation 22
1
Safe
Equations used
Deflection
120 cm
Assumed Distance between Main beams
85 t/cm2
Modulus of Elasticity
4600 cm4
Moment of Inertia
Secondary Beam Span
User input
User input
0.0072 t/cm
Calculated using Equation 13
Deflection
0.026 cm
Calculated using Equation 25
Allowable deflection for Secondary Beam
0.444 cm
User input (L/270)
Load
4.4 mm
Allowable deflection for Secondary Beam
1
Safe
51
4.2.5 Main Beam (Stringer)
The Main Beam must be checked against bending, shear, and deflection as follows:
A-Bending : The bending stresses is calculated using with either equation 17 or 19 depending on
the design concept; however in the equation the load used is the stringer (SW) load, and the Span
used is simply the distance between the Props (Shores). This depends on the direction of the
main beam, if the main beam is placed in the X-Direction, the used span of the main beam will
be the span of the Props in the X-direction, and the spacing between the main beam will be the
distance between props in Y-Direction, if the main beam is placed in the Y-Direction. The used
span of the main beam will the span of the props in the Y-direction, and the spacing between the
main beams will be the distance between props in the X-direction. For the bending to be safe, the
section modulus of the material has to be more than the section modulus calculated using
Equation 26
B-Shear :The Shear stresses is calculated using with equation 22; however in the equation the
load used is the stringer (SW) load, and the Span used is simply the distance between the Props
(Shores). This depends on the direction of the main beam, if the main beam is placed in the XDirection, the used span of the main beam will be the span of the Props in the X-direction, and
the spacing between the main beam will be the distance between props in Y-Direction. If the
main beam is placed in the Y-Direction, the used span of the main beam will the span of the
props in the Y-direction, and the spacing between the main beams will be the distance between
props in the X-direction. For the shear to be safe, the shear capacity of the material has to be
more than the shear force on the secondary beam
C-Deflection :The deflection is calculated using either equation 23 or 25 depending on the
design concept. However in the equation the Span used is simply the distance between the Props
(Shores). This depends on the direction of the main beam, if the main beam is placed in the XDirection, the used span of the main beam will be the span of the Props in the X-direction, and
the spacing between the main beam will be the distance between props in Y-Direction, if the
main beam is placed in the Y-Direction, the used span of the main beam will the span of the
props in the Y-direction, and the spacing between the main beams will be the distance between
props in the X-direction. For the deflection to be safe it has to be less than the maximum
deflection desired by the user.
52
D-Cantilever Main Beam: The Following equations are used for the allowable cantilever span
permitted for the main beam, the allowable span due to bending, shear, and deflection is
calculated, and the minimum outputted span is used (Alexander,2003).
Bending
Lc=√
2𝑀
𝑤
Shear
Eq. (A)
Lc=
𝑉
Deflection
4
Lc= √
Eq. (B)
𝑤
8𝐸𝐼∆
𝑤
Eq.(C)
E-Example: the following Example shown in table 5, and 6 is outputted from the model and it
shows design checks made for the main beam in case the main beam direction is the x-direction
or the y-direction respectively. The Example is using the Design loads shown in table 2
Table 5: Main Beam Design Checks outputted from the model- if the main beam direction is the x-direction
Main Beam design checks outputted from the model
if Main direction of Main beam is X-direction
Moment
Equations used
0.90 m
if X-is the main direction, therefore
Assumed Distance between Props(X-direction)
Main Beam span is 0.9m, and the
1.20 m
Assumed Distance between Props(Y-direction)
spacing between main beam is 1.2 m
0.156
15.60
143.12
460
Moment On Main Beam
Moment On Main Beam
Calculated Section Modulus (Z)
Section Modulus of Main Beam
Safe
t.m
t.cm
cm3
cm3
Calculated using Equation 19
Calculated using Equation 26
User input
1
Shear
Assumed Distance between Props(X-direction)
0.90 m
1.04 t
1.10 t
Shear Force on Main Beam
Shear Capacity of Main Beam
Safe
Equations used
if X-is the main direction, therefore
Main Beam span is 0.9m, and the
spacing between main beam is 1.2 m
Calculated using Equation 22
User input
1
Deflection
Assumed Distance between Props
Modulus of Elasticity
Moment of Inertia
Load
Deflection
Allowable deflection for Main Beam
Allowable deflection for Main Beam
Safe
90
85
4600
0.019
0.0223
0.3333
3.3333
cm
t/cm2
cm4
t/cm
cm
cm
mm
Equations used
Main Beam Span
User input
User input
Calculated using Equation 13
Calculated using Equation 25
User input (L/270)
1
53
Table 6: Main Beam Design Checks outputted from the model- if the main beam direction is the y-direction
Main Beam design checks outputted from the model
if Main direction of Main beam is Y-direction
Equations used
Moment
0.90 m
if Y-is the main direction, therefore
Assumed Distance between Props(X-direction)
Main Beam span is 1.2 m, and the
spacing between main beam is equal
1.20 m
Assumed Distance between Props(Y-direction)
to 0.9m
0.208
20.80
190.83
460
Moment On Main Beam
Moment On Main Beam
Calculated Section Modulus (Z)
Section Modulus of Main Beam
Safe
t.m
t.cm
cm3
cm3
Calculated using Equation 19
Calculated using Equation 26
User input
1
Shear
Assumed Distance between Props(Y-direction)
1.20 m
1.04 t
1.10 t
Shear Force on Main Beam
Shear Capacity of Main Beam
Safe
Deflection
Assumed Distance between Props
Modulus of Elasticity
Moment of Inertia
Load
Deflection
Allowable deflection for Main Beam
Allowable deflection for Main Beam
Safe
Equations used
if Y-is the main direction, therefore
Main Beam span is 1.2 m, and the
spacing between main beam is equal
to 0.9m
Calculated using Equation 22
User input
1
120
85
4600
0.014
0.053
0.444
4.444
cm
t/cm2
cm4
t/cm
mm
cm
mm
Equations used
Main Beam Span
User input
User input
Calculated using Equation 13
Calculated using Equation 25
User input (L/270)
1
4.2.6 Props System
A-Design Procedures: In order to have an economic Design, and properly choose the cheapest
Props, the model first checks if the shortest available prop is sufficient to carry the load or not, if
not it checks a taller Prop, it does so until it finds the safest prop with the cheapest cost. For a
prop to be chosen it has to be able to cover the clear span, and carry the vertical load. The Height
of the Prop required is calculated using Equation 37, while the Design load is calculated using
54
Equation 14’. It must be noted that if the Prop Height Calculated by Equation 37 is higher than
the maximum Prop Height, the system cannot be used.
Hp=CH-PT-SH-MH
(Equation 37)
B-Example: Calculations shown in Table 7 is outputted from the model, and it is following the
previously mentioned procedures in choosing the type of Prop based on the clear height, and
Prop capacity
Table 7: Prop Design Capacity check outputted from the model
Prop Capacity Check
Item
Height of prop system
excluding main beam and
secondary beam and
sheathing
Prop Height
Prop type used
Load on Props
E30 (3 m height prop)
E35 (3.5 m height prop)
E40 (4 m height prop)
E45 (4.5 m height prop)
Value
Unit
Equations used
2.932
m
Calculated using Equation 37
m
The minimum Height for Prop to be used
The Type of the Prop used based on the Calculations downwards
Calculated using Equation 14'
The capacity of Prop E30 based on the Extension
The capacity of Prop E35 based on the Extension
The capacity of Prop E40 based on the Extension
The capacity of Prop E45 based on the Extension
Since Prop E30 is the Cheapest Prop to satisfy the design
parameters it was chosen
3.0
E30
1.77
2.3
2.33
2.73
3.05
Allowable load on props
t
t
t
t
t
2.3 t
If the Clear Height required is more than the Height of the prop, the prop is automatically
rejected without checking its capacity as shown in table 8 example.
Table 8: Prop Design Capacity from the model showing a rejected prop although it fulfills the height requirements
Prop Capacity Check
Item
Height of prop system
excluding main beam and
secondary beam and sheathing
Prop Height
Prop type used
Load on props
E30 (3 m height prop)
E35 (3.5 m height prop)
E40 (4 m height prop)
E45 (4.5 m height prop)
Allowable load on props
Value
Unit
Equations used
4.082
m
Calculated using Equation 37
4.1
E45
1.77
0
0
1.54
1.84
m
1.84
t
The minimum Height for Prop to be used
The Type of the Prop used based on the Calculations downwards
Calculated using Equation 14'
Prop E30 does not satisfy the Height Constraint
Prop E35 does not satisfy the Height Constraint
The capacity of the E40 Prop based on the Extension
The capacity of the E45 Prop based on the Extension
Although Prop E40 satisfies the Height constraint; however, it is
not satisfy the capacity constraint; therefore prop E45 is chosen
t
t
t
t
t
55
C-Bracing: Since minimum information was provided about the Formwork elements capacity in
lateral loads, the model developed follows the manufacturer (Acrow in the case studies)
recommendation, concerning bracing for the system. Acorw recommend that the European prop
system is braced in both directions X-direction, and Y-direction so as to resist lateral loads.
However, the user can edit the number of props he would like to brace together per row based on
the number of formwork used, and the recommendation of the formwork supplier.
4.2.7 Frames System
A-Design Procedures: The Frames system consists of a P-head, and U-head both elements have
a maximum distance that they can be opened to (this distance is provided by the supplier), while
there is also a minimum distance that both P-Head, and U-Head can be closed to, and this
distance has to do with the practicality of construction; in other words, this distance is left to be
able to level the slab, if the ground on which the frame is placed is not leveled well. Both
maximum and minimum value must be inputted by the user in the model, and it is going to be
seen in the User input section.
PH=Hp-Um-Pm
(Equation 38)
B=(Uma+Pma)-(Um+Pm)
(Equation 39)
The Basic idea of the Design Procedures of the frames system, is to calculate the number of
frames required to cover the height of the slab, and determine whether or not there is a telescopic
frame. if there is a telescopic frame a check is made to indicate whether or not bracing is
required to increase the telescopic frame capacity. This was done in the model as it is going to be
observed in table 9
It must be noted that the Frames main beam have to be in the directions of the Frames, and not in
the other direction. In other words, the frames are connected by cross-brace, the main beam must
be in the same direction of the cross-brace.
B-Bracing: Since minimum information was provided about the Formwork elements capacity in
lateral loads, the model developed follows the manufacturer (Acrow in the case studies)
recommendation, concerning bracing for the system. Acorw recommend that each Shore brace
56
should be braced to the frame next to it, as a minimum requirement. However, in the program,
the user can change the number of frames he would like to brace together
Table 9: Prop Design Capacity check outputted from the model
Frame Capacity Check
Item
Value
Unit
Equations used
Height of Frame system including u-head and phead
2.932
m
Calculated using equation 37
Height of Frame system including u-head and phead with minimum distance
2.73
m
Calculated using equation 38
remaining allowable u-head and p-head distance
Dummy 1
No. Of frames
0.50
1.5178
1
m
Ratio
no.
Calculated using equation 39
Height of Frame needed/ Frame Height
Obtained by rounding down dummy 1
No. Of Telescopic Frame
Remaining for Telescopic frame
Load on props
1
no.
0.932
2.3256
m
t
1
no.
Is there bracing for telescopic frame
Allowable load on props
10.5
t
Calculate Whether or not the remaining distance
need a telescopic frame (is the remaining
distance within the Buffer available for the UHead and P-Head, if not we have to make sure
that it can be covered by the Frame Extension
which has a maximum height of 1.425m;
otherwise, the user will have to release the HHead, and P-Head maximum constraints (use
stronger elements)
Calculated using Equation 14'
A variable to optimize to insure that bracing is
used when needed only
Capacity of the Shore brace system used
4.2.8 Cuplock System
A-Design Procedures: The first step in designing a cuplock system is to know the number of
props needed in order to fill the clear height; afterwards, a very important aspect is to know the
maximum unbraced length that can be reached while having a safe design; since having less
bracing (ledgers) means having a more economical design that is why the no. of bracing required
is considered as a variable in optimization; however a maximum and minimum bracings is
calculated based on the vertical props chosen, in order to be a constraint for bracing variable. An
Example of how the props are selected in the model is shown in table 10
57
Table 10: Cuplock Prop Capacity check outputted from the model for one prop selected
Cuplock Prop Capacity Check
Height of Cuplock system
including u-head and p-head
2.932
m
calculated using Equation 37
Height of Cuplock system
including u-head and p-head
with minimum distance
2.682
m
calculated using Equation 38
remaining allowable u-head and
p-head distance
0.35
m
calculated using Equation 39
Dummy 1
5.364
First Prop
5
Second Prop
0
Third Prop
0
The Height of cuplock system including U-Head and PHead/0.5
Rounddown Dummy 1
if (Dummy 1-First Prop>U-Head and P-Head Buffer), the
needed prop is calculated
if (Dummy 1-First Prop-Second Prop>U-Head and P-Head
Buffer), the needed prop is calculated
Fourth Prop
0
Fifth Prop
0
No. of possible bracings
5
Minimum bracing
1
Maximum bracing
2
no.
1.73
1
2
2.2
t
no.
m
t
Load on props
No. of bracing
unbraced length
Allowable load on props
Safe
if (Dummy 1-First Prop-Second Prop-Third Prop>U-Head
and P-Head Buffer), the needed prop is calculated
if (Dummy 1-First Prop-Second Prop-Fourth Prop>U-Head
and P-Head Buffer), the needed prop is calculated
no. No. of Bracing Cups in the chosen props
no. constraints (Calculated based on Maximum unbraced
length)
constraints (Calculated based on Minimum unbraced
length)
Calculated using Equation 14'
Variable
Calculated based on No. of bracing
Calculated based on No. of bracing
Another Example with a clear height of 8 is shown in table 11, so as to show how the model
chooses more than one cuplock, in the most economical way, since it uses the least possible
material (Prop) to support the slab clear height
58
Length of
Prop
Needed
2.5
0
0
0
0
Table 11: Cuplock Design Procedures for more than one vertical prop selected
Cuplock Prop Capacity Check
Height of Cuplock system
including u-head and p-head
Height of Cuplock system
including u-head and p-head
with minimum distance
7.332
remaining allowable u-head
and p-head distance
0.35
Dummy 1
First Prop
Second Prop
Third Prop
Fourth Prop
Fifth Prop
No. of possible bracings
Minimum bracing
Maximum bracing
Load on props
No. of bracing
unbraced length
Allowable load on props
Safe
m
calculated using Equation 37
m
calculated using Equation 38
m
calculated using Equation 39
7.582
The Height of cuplock system including U-Head and P14.664 Head/0.5
6
Rounddown Dummy 1
if (Dummy 1-First Prop>U-Head and P-Head Buffer), the
6
needed prop is calculated
if (Dummy 1-First Prop-Second Prop>U-Head and P-Head
2
Buffer), the needed prop is calculated
0
if (Dummy 1-First Prop-Second Prop-Third Prop>U-Head
and P-Head Buffer), the needed prop is calculated
0
13
if (Dummy 1-First Prop-Second Prop-Fourth Prop>U-Head
and P-Head Buffer), the needed prop is calculated
no. No. of Bracing Cups in the choosen props
3
7
1.7334
4
2
2.2
no.
constraints (Calculated based on Maximum unbraced
length)
no.
constraints (Calculated based on Minimum unbraced
length)
Calculated using Equation 14'
Variable
Calculated based on No. of bracing
Calculated based on No. of bracing
t
no.
m
t
B-Bracing: Since minimum information was provided about the Formwork elements capacity in
lateral loads, the model developed follows the manufacturer (Acrow in the case studies)
recommendation, concerning bracing for the system. Since the cuplock is a system Where each
vertical prop is connect to the other with a horizontal ledger, its lateral resistance is better than
the Props and the Frames systems. Acorw recommend that each the cuplock system is braced
each 3 rows; however the user can change the bracing interval, and the number of vertical prop
to be braced together if desired.
59
Length of
Prop
Needed
3
3
1
0
0
4.2.9 Wood Shores
The process of designing the shores is done first by calculating the length of Shores required
using Equation 37, and then the least number of shores possible is selected. The shore vertical
capacity can be increased by doing bracing using the same concept of the cuplock system
however there is no maximum or minimum bracing required, and the bracing interval is
considered a variable in the optimization Process; however, if there is no bracing required to
increase the shore vertical capacity one row of bracing is added in both directions so as to resist
the lateral loads. In Egypt, from a practical point of view, the conventional wood formwork is
braced in both directions. Therefore, in the model the wood formwork is braced from the two
directions; however the user can change the number of shores he wants to be braced together
4.3 Quantity Take-Off
The Quantity Takeoff concept followed in this model is summarized in figure 48; however, first
we have to define what is meant by Available area, non-Available areas. In the user input
section, there will be an explanation for how the user can input each area; however, available
area is simply the boundary of the building (The Area for which the formwork system will be
installed), while the unavailable area include all the areas where no horizontal formwork is
required like columns, cores, voids, and etc.
Figure 48: Summary of the Quantity Take-off procedures followed in the model
60
4.3.1 Props System
A-Available Area
The Props system quantity is calculated first based on the available area; as if there is no
obstruction. Calculations are done as shown in table 12 , where the number of props per xdirection and y-direction is calculated and multiplied together to get the total number of
European props used
Table 12: European Prop Available area quantity take-off example
Props System Quantity Take-off for Available Area
Item
Props Spacing (X-direction)
Props Spacing (Y-direction)
x
y
approximate no. of props in Y-direction
approximate no. of props in X-direction
Total Number of Props
Value
0.5
0.6
20
25
42
Unit
m
m
m
m
no.
41 no.
1722 No.
Equation used
The Spacing of Props in X-direction (Variable)
The Spacing of Props in Y-direction (Variable)
The Length of the available area
The Width of the Available Area
Round down (The Y-direction length divided by props
spacing in Y-Direction)+1
Round down (The X-direction length divided by props
spacing in X-Direction)+1
The total number of props is Props in X-direction multiplied
by Props in Y-direction
B-Unavailable Area
For the un-available area there are two checks one is done for the y-direction, and one in the xdirection, the concept of the check is that a dummy value is calculated for each direction. The
dummy calculated is the co-ordinate of the nearest prop to the un-available area, then checks are
made where the 1st check is whether the dummy is within the boundary of the unavailable area or
not. The 2nd check is to find whether the dummy plus the spacing of prop in that direction is
within the unavailable area or not, and the 3rd check is to investigate whether the dummy plus
twice the spacing of prop in that direction is within the unavailable area or not, and so on. After
checks are done in both directions, the total number of props obstructed by the unavailable area
is calculated. Figure 49 shows an unavailable area obstructing two props, and table 13 shows
how it is calculated based on the previously mentioned steps
Figure 49: Props obstructed by un-available area (column) check
61
Table 13: Example from the model for Calculating props obstructed by the unavailable area
Props System
un-available area 1
does the area obstruct the props
Y1
2.5 Dummy
Y4
3.7
1ST Check (YD)
0
2ND Check(YD)
1
3RD Check(YD)
1
4th Check(YD)
0
5th Check(YD)
0
6th check(YD)
0
7th check(YD)
0
8th check(YD)
0
9th check(YD)
0
10th check(YD)
0
No. of props Removed
2
2.4 X1
X2
1ST Check (XD)
2ND Check(XD)
3RD Check(XD)
4th Check(XD)
5th Check(XD)
6th check(XD)
7th check(XD)
8th check(XD)
9th check(XD)
10th check(XD)
2.3 Dummy
2.9
0
1
0
0
0
0
0
0
0
0
2
Multiplication
0
1
1
0
0
0
0
0
0
0
The Second check that is done while performing a quantity take-off for the prop in the unavailable areas is to ensure that after the props are removed due to the un-available obstruction,
the allowable cantilever distance for the main beam as shown in figure 50 is satisfied. Otherwise
a prop needs to be added, and this check is done in X1, and X2 directions if the Main Beam
direction is the X-Direction, and Y1, and Y4 direction if the main beam direction is the ydirection as shown in figure 51
Figure 50: Main beam cantilever check example
Figure 51: Main Beam Cantilever check directions
62
4.3.2 Frames system
A-Available Area
Calculating the number of frames in the available area for the frames system is different than the
Props system, since the Prop is a single unit that can be removed. However, the frame consists of
two props braced together, in addition to the crossbrace that connects each two frames together,
the procedures of Quantity take-off of Frame system in available area are shown in table 14, and
the number of the crossbrace is calculated using Equation 40, and 41 depending on the main
direction of the Frame.
If X-is the Main Direction
CBQ= ((LA-1)*2)*WA
Eq. (40)
If Y-is the Main Direction
CBQ=((WA-1)*2)*LA
Eq. (41)
Table 14: Frames System Quantity Take-off
Frames system quantity take-off
if Frame main direction is x-direction
no. of spacing
15
no.
6
m
remaining distance for
frames
19
m
no. of rows
15
no.
no. of spacing
12
no.
distance taken by spacing
4.8
m
15.2
m
distance taken by spacing
remaining distance for
frames
no. of rows
12
no.
Spacing Between Frames
0.4
m
Crossbrace length
0.9
m
x
y
20
25
m
m
Calculated by Dividing the Y-Direction Length by the summation of The Frame width, and the
spacing between Frames
Calculated by multiplying the no. of spacing with the Spacing between frames
Calculated by subtracting the Y-direction Length from the distance taken by spacing
Calculated by Dividing the remaining distance for frames by the Frame width
IF Frame main direction is y-direction
Calculated by Dividing the X-Direction Length by the summation of The Frame width, and the
spacing between Frames
Calculated by multiplying the no. of spacing with the Spacing between frames
Calculated by subtracting the X-direction Length from the distance taken by spacing
Calculated by Dividing the remaining distance for frames by the Frame width
Frame Available Area Quantity
Variable in the optimization process (The Distance between Frames)
Variable in the optimization process (The Cross-brace length connecting Frames)
The Length of the available area
The Width of the Available Area
Y-direction
15
no.
Since, in this Example the main direction of the Frame is the X-Direction the no. of rows is
calculated as shown above(Highlighted in Red), if the y-direction was the main this number would
have been calculated by dividing the width of the Available area by the Crossbrace length
X-direction
24
no.
Since, in this Example the main direction of the Frame is the X-Direction; therefore, the no. Frames
is calculated by dividing the Length of the available area by the crossbrace length, if the y-direction
was the main this number would have been the calculated as shown above (Highlighted in Green)
Total Crossbrace
690
no.
Calculated using Equation 40 or 41 depending on main direction
63
B-un-available area
There is a difference between the props system, and the frames system, when it comes to
quantity take-off for unavailable area. As shown in table 14 for the unavailable area quantity
takeoff for props system, there are two checks done one in the y-direction, and the other is in the
x-direction, in order for that to be done for the Frames system, the check has to vary depending
on the frame direction. In other words, if the frame main direction is the X-direction, The Ydirection Check will be concerned with whether or not there is a Frame row that will pass
through the un-available area, and the x-direction check, will be concerned with the number of
frames in the un-available area, these checks will be exchanged in case the Y-direction is the
main direction of the Frames, since the X-direction will check whether or not there is a row of
frames passing through the un-available area, and the Y-Direction check will be concerned with
the number of frames inside the un-available area; how this is done in the model for the example
shown in figure 52 is discussed in details in table 15 for the Y-direction checks, and the Xdirection checks.
Figure 52: Example used for calculation of Frames quantities in un-available areas
64
Table 15: Frames un-available areas Quantity Take-off checks
Un-Available Areas
Frames (Y-Direction Checks)
Y1
1.4
Y4
2.9
1ST Check
(YD)
1
2ND
Check(YD)
0
3RD
Check(YD)
0
4th Check(YD)
0
5th Check(YD)
0
Check Explanation
If X-direction is the Main
Checks Whether Frame 1
row is within the range of
the un-available area
Checks Whether Frame 2
row is within the range of
the un-available area
Checks Whether Frame 3
row is within the range of
the un-available area
Checks Whether Frame 4
row is within the range of
the un-available area
Checks Whether Frame 5
row is within the range of
the un-available area
if Y-direction is the main
Checks Whether Dummy is within
the Range of un-available area
Checks Whether
Dummy+Crossbrace Length is
within the Range of un-available
area
Checks Whether
Dummy+2*Crossbrace length is
within the Range of un-available
area
Checks Whether
Dummy+3*Crossbrace length is
within the Range of un-available
area
Checks Whether
Dummy+4*Crossbrace length is
within the Range of un-available
area
Dummy
0.9
Dummy2
1.2
no. of
spacing
0
remaining
distance for
frame
1.4
no. of
frames
1
Frame 1
Calculates the Nearest
Frame position in case that
main direction is the YDirection
Calculations Made to get
the co-ordinates of Frame
Rows Nearest to the
inputted un-available area
in case the main direction
is the X-Direction
1.6
Beginning of Frame 1
2.8
End of Frame 1
Un-Available Areas
Frames (X-direction Check)
X1
2.5
X2
4
1ST Check
(XD)
0
2ND
Check(XD)
1
3RD
Check(XD)
1
4th Check(XD)
0
5th Check(XD)
0
Check Explanation
If Y-direction is the Main
Checks Whether Frame 1
row is within the range of
the un-available area
Checks Whether Frame 2
row is within the range of
the un-available area
Checks Whether Frame 3
row is within the range of
the un-available area
Checks Whether Frame 4
row is within the range of
the un-available area
Checks Whether Frame 5
row is within the range of
the un-available area
if X-direction is the main
Checks Whether Dummy is within
the Range of un-available area
Checks Whether
Dummy+Crossbrace Length is
within the Range of un-available
area
Checks Whether
Dummy+2*Crossbrace length is
within the Range of un-available
area
Checks Whether
Dummy+3*Crossbrace length is
within the Range of un-available
area
Checks Whether
Dummy+4*Crossbrace length is
within the Range of un-available
area
65
Dummy
1.8
Dummy2
1.6
no. of
spacing
1
remaining
distance
for frame
2.1
no. of
frames
1
Frame 1
Calculates the Nearest
Frame position in case
that main direction is
the X-Direction
Calculations Made to
get the co-ordinates of
Frame Rows Nearest to
the inputted unavailable area in case
the main direction is the
Y-Direction
1.6
Beginning of Frame 1
2.8
End of Frame 1
The Crossbrace removed quantity is calculated using the following equations
If Main Direction is the X-direction
If Main Direction is the Y-direction
CBQR=(FX+1)*(FY*2)
CBQR=(FY+1)*(FX*2)
Eq. (42)
Eq.(43)
The same check done for the Props system, concerning the Cantilever check for the main beam is
also done in the frames system, and in case the cantilever distance is exceeding the calculated
allowable main beam cantilever distance a frame is added with two cross braces
A very important check is done in order to avoid the case shown in figure 53, where the
unavailable area obstructed part of the frame resulting in increasing the unsupported span of the
main beam. Therefore, having an unsafe design, there is a check that is made to solve such
problem, and the solution made is shown in figure 54, where frames are added in a direction
opposite to the main direction of the frames on the boundary of the unavailable area
Figure 53: Frames obstructed by unavailable area
Figure 54: Added frames to account for the partially obstructed
frame by un-available area
4.3.3 CupLock
The Cuplock Quantity take-off is performed the same way as for the Props system. The only
difference is the calculation for the ledger, which is as follows:
A-Available area
The Cuplock ledgers in available area are calculated using the following equations for the xdirection and the y-direction
X-Direction Ledgers
Y-Direction Ledgers
CLX=(CPx-1)*CPy Eq. (44)
CLY=(CPy-1)*CPx
66
Eq. (45)
B-un-available area
The Cuplock ledgers removed in un-available area are calculated using following equations for
the x-direction and the y-direction.
X-Direction Ledgers
RCLX=(SCPx+1)*SCPy
Y-Direction Ledgers
Eq.(46)
RCLY=(SCPy+1)*SCPx
Eq.(47)
4.3.4 Wood Shore
The quantity take-off for the Wood shore is performed similar to that of the Props System.
4.3.5 Adjacent areas
Since the user can input different available areas that might be adjacent to each other there is a
check done at the boundaries of each area at its four boundaries as seen in figure 56. If the area
does not have an adjacent area, a main beam cantilever check is done, to determine whether or
not props or frames need to be added for cantilever requirements; however, if this area needs a
prop or frames to be added for cantilever requirements, and it has an adjacent area as shown in
case two in the figure 55, no prop or frame will be added, since the adjacent area will have a prop
or a frame that will support this cantilever main beam. However, if a prop or frame is needed to
be added, since the main beam allowable cantilever span is exceeded, and there is no adjacent
area, a row will be added as shown in figure 55 case one
Case One
Case Two
Side 4
Side 1
Available
area 1
Available
area 1
Available
area 2
Available
area
Side 3
Side 2
Figure 56: Adjacent areas sides check
Main Beam allowable
cantilever distance exceeded;
therefore add a new row of
props
The Main beam is no longer a
cantlliever
Figure 55: Adjacent areas check
67
4.3.6 Main Beam
The Quantity Take-off for the main beams for the available areas are done as shown in table 16
Table 16: Main Beam Quantity Take-off for available areas
Description
Length in which main beam will be
used (LMD)
Main beam For Available areas
Value Unit
Description of Equation used
20 m
No. of overlaps
8 no.
Distance taken by overlap
2 m
The Length of the Main Beam Direction
(X or Y, a variable in the optimization
process)
Calculated by dividing LMD by the
length of Main Beam
Calculated by Multiplying the Number of
the Overlaps with Overlap Distance
Length of beam with one overlap
2.2 m
The Length of The Main Beam with one
overlap (The Start Main Beam)
Length of beam with two overlap
1.9 m
Length in which main beam
without overlap(LMDO)
18 m
The Length of the Main Beam with two
overlaps
Calculated by subtracting the LMD from
the Distance taken by overlap
is There more than two beams
edge beams length
no. of edge beams
Remaining length for main beam
No. of Main beams in one row
No. of rows
No. of Main beams
1 yes is 1 and no is 0
4.4 m
2 no.
13.2 m
9 no.
21
Dummy to insure that there is more than
one beam
calculated equal to Length of Beam with
One overlap multiplied by 2
if dummy is equal to 1, therefore 2 edge
beams are available
Calculated by subtracting LMDO from
the edge beams length
Calculated by dividing the remaining
length for main beam with the length of
beam with two overlaps
if X-direction is main direction, therefore
no. of rows is equal to Y direction Props,
if not it will be equal to the Y-direction
prop
189 No.
68
Calculated by Multiplying the No. of
rows with the Main beams in row
B-un-available Areas
The Quantity Take-off of the main beam in the unavailable area is done by first checking the
number of rows of main beam that are coinciding with the unavailable area, and then a check is
done to calculate the number of main beams obstructed by such an unavailable area, these
calculations are done if the direction of the main beam is the x-direction as shown in table 17,
which solves the main beam obstruction by the unavailable area shown in figure 57. If the
direction of the main beam is the y-direction, the same steps and checks in table 17 is done, but
the x-direction will be used to obtain the number of rows colliding with the un-available area,
and the y-direction will be used to check the number of main beams obstructed by the unavailable area. However, it is very important to note that if the number of props or Frames
obstructed by the unavailable area is less than the number of props or Frames needed for
main beam cantilever requirements main beams obstructed are not removed; however,
they may increase so as to be used for the added props or frames around the unavailable
area. The last check done for the main beam is to check whether the main beam removed due to
obstruction by the un-available area left a gap that needs to be filled by a main beam, if yes, then
can the preceding main beam to the obstructed one be replaced by a longer main beam as shown
in figure 58. If the length of the main beam needed will be more than the longest available main
beam, then the shortest main beam available to fill the gap is chosen. This check must be done on
both side of the un-available area.
Figure 57: Main Beam obstructed by un-available area
Figure 58: Main beam obstruction Check
69
Table 17: Main Beam Quantity take-off example from the model
Main Beam Quantity Take-off checks for un-avaliable area
If-X direction is the main
Y1
2.5
Y4
4
1ST Check
(YD)
2ND
Check(YD)
3RD
Check(YD)
4th
Check(YD)
Dummy
2.4
Calculates
the nearest
Main beam
row to the
unavailable
area
Explanation
X1
2.5
X2
5.4
0
Check whether the dummy is obstructed
by the un available area
1ST
Check
(XD)
1
check Whether the dummy + Prop
Distance in Y-direction is within un
available area
2ND
Check
(XD)
1
check Whether the dummy + 2*Prop
Distance in Y-direction is within un
available area
3RD
Check
(XD)
0
check Whether the dummy + 3*Prop
Distance in Y-direction is within un
available area
4th
Check
(XD)
No. of main beams
Removed
Dummy
2.2
Explanation
0
checks whether the Dummy (main
beam edge) is within the
Obstructed area or not
1
checks whether the Dummy +
Main beam length with one
overlap is within the Obstructed
area or not
1
checks whether the Dummy + 2*
Main beam length with one
overlap is within the Obstructed
area or not
0
checks whether the Dummy + 3*
Main beam length with one
overlap is within the Obstructed
area or not
4
C-Frames System special case
The quantity take-off for main beams in the frames system is different than the other three
systems. Since concerning the available area, the number of main beams in one row is calculated
using the same concept; however the number of rows is simply the number of frames rows
multiplied by 2, since each frame row has two rows of main beam. Furthermore, for the unavailable area if the same concept of quantity take-off for other systems is followed for the main
beams quantity take off for the frames system concerning the main beam rows check, this would
70
Calculates
the nearest
Main beam
to the
unavailable
area edge
cause a problem if a case similar to the one shown in figure 53 takes place, where a frame
partially falls in an un-available area, the check will not remove the 2 beams in the frame, it will
only remove 1 beam that fall inside the area. In order to overcome this issue instead of
calculating one dummy for the main beams, two dummies are calculated for the main beams row
check, one dummy represents the position of the first beam row for the Frame, and the second
dummy represents the position of the second beam row for the Frame as shown in table 18
Table 18: Main Beam Quantity Take-off for un-available areas for Frames system
Y1
Main Beam Quantity Take-off checks for un-avaliable area for Frames system
If-X direction is the main
Calculates the nearest Main beam row to the unavailable
Dummy
1.6 area by the following equation(Round down(Y1 with the
2.5
Frame width+Spacing)*(Frame width+Spacing)
Y4
4.5
1st dummy
1
checks whether the nearest beam row is in the First
Frame row(Value will be equal to 1) or Second Frame
row (Value will be equal to 2)
1ST Check (YD)
0
Check whether the dummy is obstructed by the un available area
2ND Check(YD)
1
check Whether the dummy + Frame width + Spacing between frames is within
unavailable area
3RD Check(YD)
0
1ST Check (YD)
1
2ND Check (YD)
0
3RD Check (YD)
0
check Whether the dummy + 2*(Frame width + Spacing between frames) is within
unavailable area
if 1st dummy is equal to 1 (Check whether the Main beam+Frame width is obstructed
by the un available area) if 1st dummy equal to 2 (Check Whether the Main beam+
Spacing between frames is within the unavailable area)
if 1st dummy is equal to 1 (Check whether the Main beam+ Frame width+ (Frame
width +Spacing between frames) is obstructed by the un available area) if 1st dummy
equal to 2 (Check Whether the Main beam+ Spacing between frames +(Frame width
+Spacing between frames) is within the unavailable area)
if 1st dummy is equal to 1 (Check whether the Main beam+ Frame width+ 2*(Frame
width +Spacing between frames) is obstructed by the un available area) if 1st dummy
equal to 2 (Check Whether the Main beam+ Spacing between frames + 2*(Frame
width +Spacing between frames) is within the unavailable area)
4.3.7 Secondary Beam
The quantity take-off for the secondary is preformed similar to the main beam; except that if the
main beam direction is the X-direction, the direction of the secondary beam will be the Ydirection, and the calculation will be based on so, and if the direction of the main beam is the Ydirection, then the secondary beam will be placed in the X-direction, and the calculations will be
based on what is shown in figure 59.
71
Figure 59: Arrangement of Main Beam and Secondary Beam-Main beam in Yellow, and Secondary Beam in Red
4.3.8 Sheathing
A-Available areas
The sheathing quantity take off for the available area is obtained by multiplying the length and
the width to get the area of sheathing required for the available area as shown in equation 48,
while the area of one sheathing material is calculated by multiplying the sheathing length with
the width to get the area of one sheathing material as shown in equation 49. The no. of sheathing
material required is calculated by dividing the area of the available area with the area of one
sheathing material
Aa=La*Wa
Eq. (48)
As=Ls*Ws
Eq. (49)
B-un-available areas
The Sheathing of unavailable area is calculated with the same concept it is calculated with for
available areas as shown in equations 49 and 50. while the number of sheathing material
removed due to un-available area is obtained by dividing the area of the un-available area
calculated using equation 50 with the area of one sheathing material calculated using equation
49
Aua=Lua*Wua
Eq.(50)
72
4.4 Cost Estimation
After the quantity take-off takes place for each system, the cost of each system is calculated by
simply multiplying the no. of the material, and its type with the cost of each item; however this is
not the cost used for comparison, since the cost used for comparison is calculated using the
Formwork Economic concept described in Chapter 3, and other additional costs that were added
based on the factors affecting formwork selection also discussed in chapter 1. The Cost used for
comparison was based on the Following Costs
Purchase cost for one use: This cost is calculated using Equation 27. However the salvage
value is calculated by Equation 51
Ln= Pf- (Pf*DP*OD)
(Equation 51)
Maintenance cost for one use: if available this cost is calculated using Equation 32 mentioned
in chapter 3 of this report
Modification cost for one use: if available this cost is calculated using Equation 34
Lifting & Transportation Cost for one use: This cost includes the cost for moving the
formwork elements from one place to another whether within the site boundaries, or from the
Supplier to the site
Quality Problems for one use: This cost is used so as to be added, if the user of the program
experienced quality problems that required repair to be done for any of the used system, and this
cost is more likely to happen when a rented system is used, since sometimes the condition of the
rented system affect the quality of the work produced
Time savings cost for one use: this cost is added so as for the cycle time of each formwork
system to be considered. If a system is faster than the other system, it will result in cost savings
due to the decrease in the cycle time; therefore, the indirect cost for concrete activities is reduced
Risk Cost for one use: this cost includes any risk factor that would affect the formwork system,
this cost makes more sense when the system is rented, since there is an insurance cost for the
rented items, if any of the items of the formwork rented is damaged.
Labor cost for one use: This is simply the labor cost required for each system.
Cost for Comparison for one Use= Purchase cost+ Maintenance cost+ Modification cost+
Lifting & Transportation cost + Quality Problems cost+ Risk cost+ Labor cost- Time Savings
73
4.5 Optimization
4.5.1 Variables
The Following variables shown in figure 60, 61, 62, and 63 are the variables for the cuplock,
Frames, Props, Wood respectively; these variables are the same for Area 1, Area 2, Area 3, Area
4, Area 5, and Area 6, and from Beam type 1 to Beam type 18
Area One Genes
Secondary
Beam
Spacing
Props
Spacing (XDirection)
Props
Spacing (YDirection)
Main Beam
Direction
Main Beam
Length
Single or
Double
Main Beam
Secondry
Beam
Length
Number of
Bracing for
prop
Same Genes are done
For Area 2, Area 3,
Area 4, Area 5, Area 6
Main Beam
Material
Secondary
Beam
Material
Rent or
Purchase
System
Same Genes are done
For Area 2, Area 3,
Area 4, Area 5, Area 6
Main Beam
Material
Secondary
Beam
Material
Rent or
Purchase
System
Chromosome For Cuplock System
Figure 60: Variables for Cuplock system
Area One Genes
Secondary
Beam
Spacing
Spacing
Between
Frames
Crossbrace
Length
Main Beam
Direction
Main Beam
Length
Single or
Double
Main Beam
Secondry
Beam
Length
Bracing for
Telescopic
Frame?
Chromosome For Frames System
Figure 61: Variables for Frames system
Area One Genes
Secondary
Beam
Spacing
Props
Spacing (XDirection)
Props
Spacing (YDirection)
Main Beam
Direction
Main Beam
Length
Single or
Double
Main Beam
Secondry
Beam
Length
Same Genes are done
For Area 2, Area 3,
Area 4, Area 5, Area 6
Main Beam
Material
Chromosome For Props System
Figure 62: Variables for Props System
Area One Genes
Secondary
Beam
Spacing
Props
Spacing (XDirection)
Props
Spacing (YDirection)
Main Beam
Direction
Main Beam
Length
Secondry
Beam
Length
Number of
Bracing for
prop
Same Genes are done
For Area 2, Area 3,
Area 4, Area 5, Area 6
Chromosome For Conventional wood System
Figure 63: Variables for Conventional Wood system
74
Secondary
Beam
Material
Rent or
Purchase
System
4.5.2 Constraints
The Following Constraints shown in figure 64, 65, 66, and 67 are the constraints for the cuplock,
Frames system, Props system, Wood respectively; these Constraints are the same for Area 1,
Area 2, Area 3, Area 4, Area 5, and Area 6, and from Beam type 1 to Beam type 18
Area One Constraints
Sheathing
Safe
Design (2)
Secondry
Beam Safe
Design (3)
Main Beam
Safe
Design (3)
Bearing
Capacity
Check (1)
Props Safe
Design (1)
U-Head&
P-Head
Check (2)
Same Constraints are For Area 2,
Area 3, Area 4, Area 5, Area 6, and
Beams from Type 1 to Type 18
Safe Design for Cuplock
system for all areas is (72)
and beams type is (216)
Legend
Description
(value)
Cuplock System
Figure 64: Cuplock Constraints
Area One Constraints
Sheathing
Safe
Design (2)
Secondry
Beam Safe
Design (3)
Main Beam
Safe
Design (3)
Frame Safe
Design (1)
Bearing
Capacity
Check (1)
U-Head&
P-Head
Check (2)
Same Constraints are For Area 2, Safe Design for Shorebrace
Area 3, Area 4, Area 5, Area 6, and system for all areas is (72)
Beams from Type 1 to Type 18
and beams type is (216)
Legend
Description
(value)
Frames System
Figure 65: Frames system constraints
Area One Constraints
Sheathing
Safe
Design (2)
Secondry
Beam Safe
Design (3)
Main Beam
Safe
Design (3)
Prop Safe
Design (1)
Bearing
Capacity
Check (1)
U-Head
Check (1)
Same Constraints are For Area 2,
Area 3, Area 4, Area 5, Area 6, and
Beams from Type 1 to Type 18
Props System
Safe Design for Europrop
system for all areas is (66)
and beams type is (198)
Legend
Description
(value)
Figure 66: Props system constraints
Area One Constraints
Sheathing
Safe
Design (2)
Secondry
Beam Safe
Design (3)
Main Beam
Safe
Design (3)
Prop Safe
Design (1)
Bearing
Capacity
Check (1)
Same Constraints are For Area 2,
Area 3, Area 4, Area 5, Area 6, and
Beams from Type 1 to Type 18
Conventional wood System
Figure 67: Conventional Wood Formwork Constraints
75
Safe Design for Wood
system for all areas is (60)
and beams type is (180)
Legend
Description
(value)
4.5.3 Objective Function
The objective function is to minimize the Cost used for comparison mentioned in the cost
estimation section. The user has the choice of optimizing each system separately, or the user can
optimize the total cost for comparison for all the system
The objective function is to minimize the cost of comparison
4.5.4 Software used for optimization
The software used for optimization is Evolver 5.5, which comes in palisade decision tools
software and uses Genetic algorithms in optimization, the program is an add-in to Microsoft
Excel 2007. The user inputs the variables, constraints, objective function as shown in figures 68,
and 69 (Palisade,2016)
Figure 68: Evolver 5.5 add in to excel 2007
Figure 69: Definition of variables, constraints, and objective function (Model Definition) in Evolver
76
4.6 Program limitations
The model developed in this paper has the following limitations
1- Rectangular Shape for the Geometry: the shapes that can be inputted to the model
developed can only be rectangular shapes. No triangles, circles, or irregular shapes can be used.
2-Avaliable & un-available area: the user can input up to Six available areas each area has up
to 15 un-available areas (columns, Cores, and etc.), and up to 10 Beams; however this limitation
can be overcome by inputting any new area in a new model, and optimize it separately from
other areas
3-Beams Design: There can be up to 18 Beam types, what is meant by beam types here is that
there can be 18 different depths for the beams in all six areas.
4-Beams Quantity take-off: the program does a design, quantity take-off, and cost estimation
for the beams; however, the side supports needed for the vertical sheathing of the beams is not
calculated.
5- Life cycle of the material used: the model considers up to 3 quantities of materials that can
be completely depreciated and bought again. In other words, if a material useful life is 20 times,
and the project needs to use the material 60 times, this means that 3 times the quantity of the
material needs to be bought. This cost is considered up to 3 times more than that it is not.
6-Lateral Bracing: due to the lack of design data concerning the lateral bracing of the formwork
elements, recommendation obtained from the supplier is used as an input by the user.
4.7 User input
4.7.1 Geometry
The Geometry of the building must be entered by the user, as stated in the previous section, the
user can input up to six available areas with different slabs thicknesses, and clear height. The
user can input up to 15 unavailable areas, which is defined as areas in which no formwork is
placed like vertical elements and voids; also, the user can input up to 10 beams in available
areas. Since, the model uses x and y co-ordinates for all the areas in the project in order to be
able to calculate the quantities of formwork needed. In order to facilitate the process of geometry
input, a visual basic code (shown in the Appendix) was developed in order to automatically
record the co-ordinates of the shapes that the user draw on excel; in other words, instead of
inputting co-ordinates, the user can draw rectangular shapes on a developed grid in excel, and the
77
co-ordinates of this shapes will be automatically recorded as shown in figure 70. The user has to
do is to draw the geometry using rectangles with certain color templates for each area, which are
shown in the excel model, after doing so, the user clicks on Read shapes button, so as for the coordinates to be recorded, If the user needs to re-enter any data he/she has to click on clear button,
and then input the new data
Figure 70: Geometry Input in the model using Visual basic code
4.7.2 Material related Data
The First user input is the design concept to be followed for each area, the Specific weight of the
concrete used, the live load, and the main beam, and the secondary beam overlap as shown in
figure 71. What is meant by the main beam and secondary beam overlaps is whether in the same
row the beam used overlaps with the preceding beam, if this is not desired the user can enter an
overlap value equal to zero. The Material related properties for the decking options are the area,
moment of inertia, section modulus, modulus of elasticity, allowable bending stress, shear
capacity, height of the beam, and the weight per meter. An example for the material properties
inputted to the model is shown in figure 72
Figure 71: General Design Data for user input
78
Figure 72: Material Related Properties input (H-20) Example
For the formwork options considered all the data concerning the capacity of the prop at different
extensions is required for the Props system, and the frames systems capacity with, and without
bracing for the telescopic frame. Regarding the cuplock and wood formwork systems the
capacity of the vertical shores in relation to the un-braced length of the vertical shore is needed.
In addition, the capacity of the U-Head, and the P-head used for each formwork system is
needed, and the weights of each component of the formwork system. An example of the needed
material properties data for the props system is shown in figure 73
Figure 73: False work Material Related Properties input-Props system Example
79
4.7.3 Cost related data
In the model, there are cost related data inputted for each of the formwork components. In
General, the user inputs the yearly interest rate, and the project duration. For main and secondary
beam options, the user has to input the cost of each length of the beams, number of uses per year
for the selected materials, the useful life of the material (the number of uses till
disposal),maintenance cost, modification cost, and the depreciation per year for the material if
needed as shown in figure 74. However for the false work options, the user has to input the same
data entered for main and secondary beam in addition to lifting & Transportation costs, quality
costs, Time saving cost, Risk cost, Labor cost for one use as shown in figure 75.
Figure 74: Cost Related Data for H20
Figure 75: Cost Related Data For European Prop
80
4.8 User output
The output of the model is design data for the user as shown in figure 76, where different design
parameters for each of the formwork system per area is outputted for the user. This design is
graphically represented in figure 77, showing the main grids for the main, and secondary beams
without the un-available areas or beams; also, a quantity take-off for the amount of each
component of each formwork system is outputted. The most important output of the program is
the suitable formwork selection for the project and its purchase cost. This data is shown in figure
78, which represents as summary of the selection criteria however if the user desires to check
any calculations or to go through further details, the outline in table 19 explain all the
components of the model, so as to be a guide for the user.
Formwork Grid Output
2.8
Y-direction(m)
2.4
2
1.6
1.2
0.8
0.4
Figure 76: Outputted Design Data Example
0
0
0.4 0.8 1.2 1.6
2
2.4 2.8 3.2
X-Direction(m)
Figure 77: Formwork Grid outputted from the model
Figure 78: Formwork Selection System Output
81
Table 19: Model Excel Sheets Description
Excel Model Sheets
Description of Each Sheet
Graphical User input
User inputs
User output
Evolver data
This sheet is used to draw the available, non-available areas, and beams
Contains the user required input for the desired project
Presents a summary for the formwork system selected
Contains the Data for Optimization using GA (Variables, Constraints, and Objective Function)
Cuplock Cost
Shorebrace Cost
Wood Cost
Europrop Cost
Cuplock (Design O1)
Cuplock (Design B1)
Contains Detailed Cost Estimation for the Cuplock Components
Contains Detailed Cost Estimation for the Shorebrace Components
Contains Detailed Cost Estimation for the Conventional Wood Components
Contains Detailed Cost Estimation for the European Prop Components
Contains Design Data and calculations for Cuplock System For Available Areas
Contains Design Data and calculations for Cuplock System For Beams (From Type 1 to Type 6)
Cuplock (Design B2)
Contains Design Data and calculations for Cuplock System For Beams (From Type 6 to Type 12)
Cuplock (Design B3)
Contains Design Data and calculations for Cuplock System For Beams (From Type 12 to Type 18)
Quantity Take-off (Cuplock)
Contains Detailed Quantity Take-off for Available & Non-Available Areas using cuplock system
Quantity Take-off (Cuplock)Beams
Shorebrace (Design O1)
Contains Detailed Quantity Take-off for Beam using Cuplock system
Contains Design Data and calculations for Shorebrace System For Available Areas
Shorebrace (Design B1)
Contains Design Data and calculations for Shorebrace System For Beams (From Type 1 to Type 6)
Shorebrace (Design B2)
Contains Design Data and calculations for Shorebrace System For Beams (From Type 6 to Type 12)
Shorebrace (Design B3)
Contains Design Data and calculations for Shorebrace System For Beams (From Type 12 to Type 18)
Quantity Take-off (Shorebrace)
Contains Detailed Quantity Take-off for Available & Non-Available Areas using Shorebrace system
Quantity Take-off (SB)Beams
Wood Formwork (Design O1)
Contains Detailed Quantity Take-off for Beam using Shorebrace system
Contains Design Data and calculations for Wood Formwork System For Available Areas
Wood Formwork (Design B1)
Quantity Take-off (Wood)Beams
Europrop (Design O1)
Europrop (Design B1)
Contains Design Data and calculations for Wood Formwork System For Beams (From Type 1 to Type
6)
Contains Design Data and calculations for Wood Formwork System For Beams (From Type 6 to Type
12)
Contains Design Data and calculations for Wood Formwork System For Beams (From Type 12 to
Type 18)
Contains Detailed Quantity Take-off for Available & Non-Available Areas using Wood Formwork
system
Contains Detailed Quantity Take-off for Beam using Wood Formwork system
Contains Design Data and calculations for Europrop System For Available Areas
Contains Design Data and calculations for Europrop System For Beams (From Type 1 to Type 6)
Europrop (Design B2)
Contains Design Data and calculations for Europrop System For Beams (From Type 6 to Type 12)
Europrop (Design B3)
Contains Design Data and calculations for Europrop System For Beams (From Type 12 to Type 18)
Quantity Take-off (Europrop )
Contains Detailed Quantity Take-off for Available & Non-Available Areas using Europrop system
Quantity Take-off (Europrop )Beams
Graphical input calculations
Contains Detailed Quantity Take-off for Beam using Europrop system
Contains data outputted from the visual basic code
Wood Formwork (Design B2)
Wood Formwork (Design B3)
Quantity Take-off (Wood)
82
Chapter 5
Model Verification, Validation & Application
83
5 Chapter 5: Model Verification, Validation & Application
This chapter discusses the model verification, two design calculation by Acorw Masr for two
current real-life projects were used, and compared with the results for design from the model. In
addition, in order to validate the quantity take-off procedures, a floor plan was calculated
manually, and compared to the results from the model. Since, the cost estimation is based on the
design, and the quantity take-off, validating both the design, and quantity take-off will yield to
correct cost estimation. Then, after validating the model, it is applied on a current real-life
project in Egypt called Secon Towers, and the outputs of the model is going to be shown and
discussed in this chapter. Finally, the model is applied on a research done by Amr Fathy (2015)
on reinforced concrete design optimization for affordable housing, in which he developed a
proposed floor plan for low, and medium income housing
5.1 Formwork Design Verification
5.1.1 Porto Cairo Shorebrace System
The first design verification was done on Porto Cairo Project, and the calculation sheets used was
submitted to Porto Cairo Contractor by Acrow Masr for Shorebrace system with timber Main,
and secondary beams with material properties shown in tables 20, and 21. First, the design
parameters used by Acorw Masr shown in table 22 is inputted to the model, and then design
checks are done on each component of the formwork system.
Table 20: Properties of Main Beam used in Design Verification 1
Main Beam Timber (7.5*15cm)
Bending Capacity
Section Modulus
Shear Capacity
Area
Modulus of Elasticity
Moment of Inertia
Height of Beam
Allowable unit stress in compression perpendicular to grain
84
89
281.25
14
112.5
85000
2109.37
15
227
kg/cm2
cm3
kg/cm2
cm2
kg/cm2
cm4
cm
t/m2
Table 21: Properties of Secondary Beam used in Design Verification 1
Bending Capacity
Section Modulus
Shear Capacity
Area
Modulus of Elasticity
Moment of Inertia
Height of Beam
Secondry Beam Timber (5*10cm)
89
83.3
14
50
85000
416.67
10
kg/cm2
cm3
kg/cm2
cm2
kg/cm2
cm4
cm
Table 22: Design Parameters for Porto Cairo
Shorebrace Design Parameter used In calculation sheet by acrow
Specific Weight of Concrete
2.5 t/m2
Live Load
0.2 t/m2
Distance Between Secondary beams
0.40 m
Distance Between Main Beam
1.5 m
Main Direction for Main Beam & Frame
X
Spacing Between Frames
1.50 m
Cross Brace Length
1.50 m
Figures 79,80, 81, 82 are calculation sheets for formwork design done by Acrow, while tables
show output from the model including the design checks.
Figure 79: Porto Cairo Acrow calculation sheet one
Figure 80: Porto Cairo Acrow calculation sheet two
85
Figure 81: Porto Cairo Acrow calculation sheet three
Figure 82: Porto Cairo Acrow calculation sheet four
Model Output
Table 23: Design Loads from the model
Design Loads
Dead load
Live Load (User input)
Live Load (Design)
Weight of formwork
Design Load
Total Load (For Sheathing)
Total Load (For Secondary Beam)
Total Load (For Main Beam)
Total Load( Shorebrace frame Design)
0.5
0.2
0.2
0.0
0.7
0.7
0.28
0.945
2.835
86
t/m2
t/m2
t/m2
t/m2
t/m2
t/m
t/m
t/m
t
Calculated
User input
Calculated
Calculated
Calculated
Calculated
Calculated
Calculated
Calculated
Table 24: Plywood Design Checks from the model
Plywood
Moment
Assumed Distance between secondary beams
Moment On Plywood section
Moment On Plywood section
Calculated Section Modulus (Z)
Section Modulus of Plywood
Safe
Deflection
Assumed Distance between secondary beams
Modulus of Elasticity
Moment of inertia
Load
Deflection
Allowable deflection for sheathing
Allowable deflection for sheathing
Safe
0.4
0.011
1.12
13.18
54
m
t.m
t.cm
cm3
cm3
40
56.4
48.6
0.007
0.0451
0.148
1.48
cm
t/cm2
cm4
t/cm
cm
cm
mm
Table 25: Secondary Beam Design Checks from the model
Secondary Beam
Moment
Spacing Between Frames
Cross brace length
Moment On Secondary Beam
Moment On Secondary Beam
Calculated Section Modulus (Z)
Section Modulus of Secondary Beam
Safe
Shear
Spacing Between Frames
Cross brace length
Shear Force on Secondary Beam
Shear Capacity of Secondary Beam
Safe
Deflection
Span of Secondary Beam
Modulus of Elasticity
Moment of Inertia
Load
Deflection
Allowable deflection for Secondary Beam
Allowable deflection for Secondary Beam
Safe
1.5
1.5
0.063
6.3
70.79
83.3
1.5
1.5
0.25
0.7
150
85
416.67
0.0028
0.276
0.556
5.556
87
m
m
t.m
t.cm
cm3
cm3
m
m
t
t
cm
t/cm2
cm4
t/cm
cm
cm
mm
Table 26: Design for main beam from the model
Main Beam
Moment
Spacing Between Frames
Cross brace length
Moment On Main Beam
Moment On Main Beam
Calculated Section Modulus (Z)
Section Modulus of Main Beam
Safe
Shear
Cross brace length
Shear Force on Main Beam
Shear Capacity of Main Beam
Safe
Deflection
Cross brace length
Modulus of Elasticity
Moment of Inertia
Load
Deflection
Allowable deflection for Main Beam
Allowable deflection for Main Beam
Safe
1.5
1.5
0.21
21.3
238.90
281.25
m
m
t.m
t.cm
cm3
cm3
1.5 m
0.85 t
1.58 t
150
85
2109.37
0.00945
0.184
0.556
5.556
cm
t/cm2
cm4
t/cm
cm
cm
mm
Table 27: Frame Capacity check from the model
Frame Capacity Check
Load on props
Is there bracing for telescopic frame
Allowable load on props
Safe
2.84
1
10.5
t
no.
t
0.42
0.015
28
227
ton
m2
t/m2
t/m2
Table 28: Other Design checks from the model
Bearing Capacity check
Load on Main Beam
Bearing Area
Actual unit stress in compression perpendicular to grain
Allowable unit stress in compression perpendicular to grain
Safe
U-head capacity Check
Load on Frame
Allowable Vertical load on U-Head
Safe
P-head capacity Check
Load on props
Allowable Vertical load on P-Head
Safe
88
1.42 t
7.1 ton
1.42 t
7.1 ton
Comments on the outputted data: The checks done in Acrow calculation sheet has exactly the
same values as those resulted from the model. This means that the model successfully designed
the desired projects using the same design parameters of Acrow.
5.1.2 Secon Nile Tower European Prop System
The second design verification was done on Secon nile towers Project, and the calculation sheets
used was submitted to Arabetc & SIAC by Acrow Masr for European prop system with Double
H20 Main-beam, and H-20 secondary beams with material properties shown in table 29. First,
the design parameters used by Acorw Masr shown in table 30 is inputted to the model, and the
different design checks for formwork components are done.
Table 29: Properties of Main & Secondary Beam used in Design Verification 2
H20
Bending Capacity
Section Modulus
Shear Capacity
Area
Modulus of Elasticity
Moment of Inertia
Height of Beam
109
460
10.7
102.4
85000
4600
20
kg/cm2
cm3
kg/cm2
cm2
kg/cm2
cm4
cm
Table 30: Design Parameters for Design Verification 2
European Prop Design Parameters used by Acrow in calculation sheet
Specific Weight of Concrete
2.5
t/m3
Live Load
0.2
t/m2
Distance Between Secondary beams
0.424
m
Distance Between Main Beam
1.4
m
Main Direction for Main Beam
X
Props Distance (X-direction)
1.6
m
Props Distance (Y-direction)
1.4
m
Figures 83,84, 85 are calculation sheets for formwork design done by Acrow, while tables show
the output from the model including the design checks.
89
Figure 83: Secon Nile Tower Acrow calculation sheet one
Figure 84: Secon Nile Tower Acrow calculation sheet two
Figure 85: Secon Nile Tower Acrow calculation sheet three
)
90
Model Output
Table 31: Design Loads from the model
Design Loads
Dead load
Live Load (User input)
Live Load (Design)
Weight of formwork
Design Load
Total Load (For Sheathing)
Total Load (For Secondary Beam)
Total Load (For Main Beam) (X-direction)
Total Load (Props Design)
1.125
0.2
0.2
0.0
1.325
1.325
0.5618
1.855
2.968
t/m2
t/m2
t/m2
t/m2
t/m2
t/m
t/m
t
Calculated
User input
Calculated
Calculated
Calculated
Calculated
Calculated
Calculated
Calculated
Table 32: Plywood Design Checks from the model
Plywood
Moment
Assumed Distance between secondary beams
Moment On Plywood section
Moment On Plywood section
Calculated Section Modulus (Z)
Section Modulus of Plywood
Safe
Deflection
Assumed Distance between secondary beams
Modulus of Elasticity
Moment of inertia
Load
Deflection
Allowable deflection for sheathing
Allowable deflection for sheathing
Safe
0.424
0.024
2.382
28.02
54
m
t.m
t.cm
cm3
cm3
42.4
56.4
48.6
0.013
0.108
0.157
1.57
cm
t/cm2
cm4
t/cm
cm
cm
mm
1.6
1.4
0.110
11.01
101.02
460
m
m
t.m
t.cm
cm3
cm3
Table 33: Secondary Beam Design Checks from the model
Secondary Beam
Moment
Assumed Distance between Props(X-direction)
Assumed Distance between Props(Y-direction)
Moment On Secondary Beam
Moment On Secondary Beam
Calculated Section Modulus (Z)
Section Modulus of Secondry Beam
Safe
91
Shear
Assumed Distance between Props(X-direction)
Assumed Distance between Props(Y-direction)
Shear Force on Secondary Beam
Shear Capacity of Secondary Beam
Safe
Deflection
Assumed Distance between Main beams
Modulus of Elasticity
Moment of Inertia
Load
Deflection
Allowable deflection for Secondary Beam
Allowable deflection for Secondary Beam
Safe
1.6
1.4
0.47
1.10
140
85
4600
0.00562
0.038
0.3
3
m
m
t
t
cm
t/cm2
cm4
t/cm
cm
cm
mm
Table 34: Main Beam Design Check from the model
Main Beam
Moment
Assumed Distance between Props(X-direction)
Assumed Distance between Props(Y-direction)
Moment On Main Beam
Moment On Main Beam
Calculated Section Modulus (Z)
Section Modulus of Main Beam
Safe
Shear
Assumed Distance between Props(X-direction)
Shear Force on Main Beam
Shear Capacity of Main Beam
Safe
Deflection
Assumed Distance between Props
Modulus of Elasticity
Moment of Inertia
Load
Deflection
Allowable deflection for Main Beam
Allowable deflection for Main Beam
Safe
1.6
1.4
0.47
47.5
217.8
920
m
m
t.m
t.cm
cm3
cm3
1.6 m
1.78 t
2.19 t
160
85
4600
0.0186
0.214
0.3
3
cm
t/cm2
cm4
t/cm
cm
cm
mm
Comments on the outputted data: The checks done in the calculation sheet has exactly the
same values as those outputted from the model. This means that the model successfully designed
the desired projects using the inputted parameters, which are going to be variables to be
optimized in the model
92
5.2 Quantity Take-off Verification
In order to verify the quantity take-off obtained from the model, a floor plan was developed, not
from a real-life project, but it was developed to include several un-available areas (columns, and
Core walls), and several beams in order to be able to verify different checks done by the model.
The floor plan used for verification is shown in figure 86. The Slab is assumed to be 30 cm,
Beam Type 1 has a depth of 60cm, and Beam Typ2 2 has depth of 50cm
Figure 86: Floor Plan Used for Quantity Take-off Verification
93
First, The Geometry of the Floor Plan was inserted to the program as shown in table 35
Table 35: Quantity Take-off verification Area Co-ordinates
Area
One
1
2
3
4
5
6
7
8
9
X1
X2
X3
0
23
23
Y1
Y2
Y3
0
0
25
Unavailable areas
X1
X2
X3
2
3
3
Y1
Y2
Y3
2
2
3
X5
X6
X7
11
12
12
Y5
Y6
Y7
2
2
3
X9
X10
X11
20
21
21
Y9
Y10
Y11
2
2
3
X13
X14
X15
2
3
3
Y13
Y14
Y15
12.0
12.0
13.0
X17
X18
X19
9
14
14
Y17
Y18
Y19
10.0
10.0
15.0
X21
X22
X23
20
21
21
Y21
Y22
Y23
12
12
13
X25
X26
X27
2
3
3
Y25
Y26
Y27
22
22
23
X29
X30
X31
11
12
12
Y29
Y30
Y31
22
22
23
X33
X34
X35
20
21
21
Y33
Y34
Y35
22
22
23
X4
0
Y4
25
X4
2
Y4
3
X8
11
Y8
3
X12
20
Y12
3
X16
2
Y16
13.0
X20
9
Y20
15.0
X24
20
Y24
13
X28
2
Y28
23
X32
11
Y32
23
X36
20
Y36
23
1
2
3
4
5
6
7
8
94
X1
3
Y1
2
X5
12
Y5
2
X9
20
Y9
3
X13
20
Y13
13
X17
12
Y17
22
X21
3
Y21
22
X25
2
Y25
13
X29
2
Y29
3
Beams
X2
11
Y2
2
X6
20
Y6
2
X10
21
Y10
3
X14
21
Y14
13
X18
20
Y18
22
X22
11
Y22
22
X26
3
Y26
13
X30
3
Y30
3
X3
11
Y3
3
X7
20
Y7
3
X11
21
Y11
12
X15
21
Y15
22
X19
20
Y19
23
X23
11
Y23
23
X27
3
Y27
22
X31
3
Y31
12
X4
3
Y4
3
X8
12
Y8
3
X12
20
Y12
12
X16
20
Y16
22
X20
12
Y20
23
X24
3
Y24
23
X28
2
Y28
22
X32
2
Y32
12
5.2.1 Props System
Quantity take-off for props system was done manually, and using the model. A check was done
on the Props Calculations, Main Beam calculations, Secondary Beam calculations was done
manually using the rules previously discussed in the chapter 4 (model methodology), and
AutoCad, and was compared to results from the model. The Design Parameters used in the
quantity take-off is highlighted in table 36
Table 36: Design Parameters used in the quantity take-off
Design Parameters
Distance Between Secondary beams
Distance Between Main Beam
Main Direction for Main Beam
Props Distance (X-direction)
Props Distance (Y-direction)
Main beam overlap
Secondary beam overlap
Allowable cantilever length for main beam
0.40
1.4
X
1.20
1.40
0.3
0.3
0.64
m
m
m
m
m
m
m
A- Props
Figure 87 shows the quantity take-off for props done manually
Figure 87: Props Manual Quantity take-off
The manual quantity Take-off resulted into the same quantity take-off obtained from the model
which is a total number of 381 European Prop as shown in table 37 ,which gives the detailed
quantity take-off for the European Props
95
Table 37: Detailed Quantity Take-off for European Props outputted from the model
Area
Available Area
un-Available Area 1
un-Available Area 2
un-Available Area 3
un-Available Area 4
un-Available Area 5
un-Available Area 6
un-Available Area 7
un-Available Area 8
un-Available Area 9
Beam 1
Beam 2
Beam 3
Beam 4
Beam 5
Beam 6
Beam 7
Beam 8
No. of props
Add
Remove
380
0
2
1
2
1
2
1
3
1
0
12
3
1
3
1
3
1
3
1
7
7
7
7
6
6
6
6
7
7
7
7
6
6
6
6
Total No. of Props
Total Added
Total Removed
453
72
Total No. of props used
B- Main Beam
Figure 88 shows the quantity take-off for main beams done manually.
Figure 88: Manual Quantity Take-off for Main Beam
96
381
The manual quantity Take-off resulted into the same quantity take-off obtained from the model
which is a total number of 204Main Beams. Table 38, and 39 shows detailed quantity take-off
for the Main Beam. The reason why there is no main beams removed from the beams is that all
the props removed due to un-available area obstruction was used again to fulfill cantilever
requirements
Table 38: Detailed Quantity Take-off for main beams
No. of Main Beams
Area
Add(X1,Y1)
Type
Remove
Type
Add(X1,Y1)
Type
Add(X2.Y2)
Type
Add(X2,Y2)
Type
198
2.5
0
0
0
0
0
0
0
0
0
0
-1
2.5
0
0
0
0
1
2.5
0
0
-1
2.5
0
0
0
0
1
2.5
0
0
-1
2.5
0
0
0
0
1
2.5
0
0
-2
2.5
0
0
0
0
1
2.5
0
0
12
2.5
0
0
3
4.5
0
0
0
0
-2
2.5
0
0
0
0
1
2.5
0
0
-2
2.5
0
0
0
0
1
2.5
0
0
-2
2.5
0
0
0
0
1
2.5
0
0
-2
2.5
0
0
0
0
1
2.5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Available Area
un-Available
Area 1
un-Available
Area 2
un-Available
Area 3
un-Available
Area 4
un-Available
Area 5
un-Available
Area 6
un-Available
Area 7
un-Available
Area 8
un-Available
Area 9
Beam 1
Beam 2
Beam 3
Beam 4
Beam 5
Beam 6
Beam 7
Beam 8
Table 39: Quantity Take-off Summary
Main Beam Length
2.5
4.5
Quantity
207
3
97
C- Secondary Beam
Figure 89 shows the quantity take-off for secondary beams done manually
Figure 89: Manual Quantity Take-off for the secondary beam
The manual quantity Take-off resulted into the same quantity take-off obtained from the model
which is a total number of 488Secondary Beams. Table 41 shows detailed quantity take-off for
the Secondary Beam. However there was a difference between the required beam lengths from
the manual calculations, and the model Quantity take-off. This difference is due to the beams,
since when an unavailable area does a check to fill the secondary beam gap around it, it removes
a 2.5 m beam, and replaces it with a longer beam to fill the gap; while this beam is already
obstructed by a beam area, therefore it is removed once again when beams checks are done
resulting into reducing the number of the used main beam length, with another length. This
problem only takes-place when there is a plan crowded with several beams. Therefore this check
causing such a problem was not corrected, since it will cause underestimation in the cost of
formwork if the building system is a flat slab without marginal beams. The difference in
quantities and the resulting difference in cost are highlighted in table 40. The resulted different in
the cost of secondary beam is equal to 3% of the total secondary beam cost, which will affect the
total cost of Formwork system as a whole with less than 1% therefore the difference is
acceptable.
98
Table 40: Comparison between Model Secondary Beam Quantities, and Manual calculations
Comparison between Model Outputted Quantities, and Manual Calculation Quantities
Model
Manual
Manual calculations
Model Secondary
Length(m)
Calculated
Quantity
Cost/unit
Secondary Beam
Beam cost-estimate
Quantities
Take-off
cost
2.5
332
374
215
71,380
80,410
3.3
19
13
284
5,396
3,692
3.9
119
101
335
39,865
33,835
2.9
6
0
250
1,500
0
3.6
6
0
310
1,860
0
4.5
6
0
389
2,334
0
Total
488
488
122,335
117,937
Table 41: Detailed Quantity Take-off for Secondary Beam outputted from the model
No. of Secondary Beams
Area
Add(X1,Y1)
Type
Remove
Type
Add(X1,Y1)
Type
Add(X2.Y2)
Type
Add(X2,Y2)
Type
696
2.5
0
0
0
0
0
0
0
0
0
0
6
2.5
0
0
3
3.9
0
0
0
0
6
2.5
0
0
3
3.9
0
0
0
0
6
2.5
0
0
3
3.9
0
0
3
3.6
6
2.5
0
0
3
2.9
0
0
13
3.9
65
2.5
0
0
13
3.3
0
0
3
3.6
9
2.5
0
0
3
2.9
0
0
0
0
6
2.5
0
0
3
3.9
0
0
0
0
6
2.5
0
0
3
3.9
0
0
0
0
6
2.5
0
0
3
3.9
0
0
Beam 1
0
0
40
2.5
0
0
20
3.9
0
0
Beam 2
0
0
42
2.5
0
0
21
3.9
0
0
Beam 3
3
3.3
21
2.5
0
0
3
3.9
0
0
Beam 4
3
4.5
21
2.5
0
0
0
0
0
0
Beam 5
0
0
42
2.5
0
0
21
3.9
0
0
Beam 6
0
0
40
2.5
0
0
20
3.9
0
0
Beam 7
3
4.5
21
2.5
0
0
0
0
0
0
Beam 8
3
3.3
21
2.5
0
0
3
3.9
0
0
Available Area
un-Available
Area 1
un-Available
Area 2
un-Available
Area 3
un-Available
Area 4
un-Available
Area 5
un-Available
Area 6
un-Available
Area 7
un-Available
Area 8
un-Available
Area 9
99
5.2.2 Frames System
Since the frames system follows a different concept in quantity take-off that is different than the
concept of Props system, manual calculations was done as shown in figure 90, and compared to
the quantity take-off of the frames, and cross brace outputted from the model shown in table 42
and table 43, and they both obtained the same result which is 234 Frames, (136) 0.9 m cross
brace and (172) 1.5 m cross brace. The spacing between frames used is 1 meter, frame width
equals to 1.2m, and crossbrace length equals to 1.5 m
Figure 90: Manual Quantity Take-off for Frames system using Acrow shorebrace frame dimensions
100
Table 42: Frames Detailed Quantity Take-off from the model
Area
Available Area
un-Available Area 1
un-Available Area 2
un-Available Area 3
un-Available Area 4
un-Available Area 5
un-Available Area 6
un-Available Area 7
un-Available Area 8
un-Available Area 9
Beam 1
Beam 2
Beam 3
Beam 4
Beam 5
Beam 6
Beam 7
Beam 8
No. of Frames
Add
Remove
192
0
3
1
3
1
3
1
3
1
2
8
3
1
3
1
3
1
3
1
11
6
11
6
9
5
7
5
11
6
11
6
7
5
9
5
Total No. of Frames
Total Added
Total Removed
294
60
Total No. of Frames
used
234
Table 43: Crossbrace Quantity Take-off from the model
Type
0.9
1.2
1.5
1.8
2.1
2.4
2.7
Cross brace
Add
Remove
136
0
0
0
360
188
0
0
0
0
0
0
0
0
total
136
0
172
0
0
0
0
5.2.3 Cuplock Ledger
Since one of the special cases for quantity take-off that needs to be checked is the cuplock
ledger, manual calculations was done as shown in figure 91, and compared to the quantity takeoff of the cuplock ledger outputted from the model as shown in table 44. Both gave the same
results which are (60) 0.6 ledger, (24) 0.9 ledger and (504) 1.2 ledger
101
Table 44: Cuplock ledger quantity take-off outputted
from the model
Type
0.6
0.9
1.2
1.5
1.8
2.1
2.4
Cuplock ledger
Add
Remove
60
0
24
0
838
334
0
0
0
0
0
0
0
0
total
60
24
504
0
0
0
0
Figure 91: Cuplock Ledger manual quantity take-off
5.2.4 Beams
Concerning the Beam Quantity take-off check, Frames formwork system for beams was checked
by manual calculation as shown in figures 92 and 93 and it gave the same results as the model
output. The design parameters used in quantity take-off is a cross brace length equal to 1.2 m,
and a 1.2 width Frame, a 1.2 m width telescopic frame, and 40 cm spacing between secondary
beam. The manual calculation is shown in figures 92,93, and the detailed quantity take-off
outputted from the model is shown in table 45
Figure 92: Beam One Main beam & Secondary Beam configuration
102
Figure 93: Beam one Frame, and main beam plan
Table 45: Frame system detailed quantity take-off for beam one
Frames System
Summary
x
8
m
y
1
m
approximate no. of props in Y-direction
1
no.
approximate no. of props in X-direction
7
no.
Main beam
Number of Telescopic Frames
Total Crossbrace
Number of Main Beam
Number of Secondary Beam
Length in which main beam will be used
No. of overlaps
Distance taken by overlap
Length of beam with one overlap
Length of beam with two overlap
Length in which main beam without overlap
is There more than two beams
edge beams length
no.of edge beams
Remaining length for main beam
No. of Main beams in one row
No. of rows
No. of Main beams
Secondary beam
Main direction for secondary beam
Length in Which Secondary beam will be used
No. of overlaps
Distance taken by overlap
Length of beam with one overlap
Length of beam with two overlap
Length in which Secondary beam without
overlap
is There more than two beams
edge beams length
no.of edge beams
Remaining length for Secondary beam
No. of Secondary beams in one row
No. of rows
No. of Secondary Beams
8
3
1
2.2
1.9
7
1
4.4
2
2.7
4
2
8
Y
1
0
0
2.2
1.9
1
0
0.0
0
1
1
20
20
m
no.
m
m
m
m
yes is 1 and no is 0
m
no.
m
no.
No.
m
no.
m
m
m
m
yes is 1 and no is 0
m
no.
m
no.
no.
no.
Sheathing
Length
1.20
m
Width
2.40
m
Area of one Sheathing material
2.88
m2
Total Area
8
m2
Side Sheathing length
8
m
Side Sheathing Area
9.6
m2
7
no.
No. of Sheathing Material
Number of Shorebrace Frames
103
No. of Sheathing Material
7
7
12
8
20
7
5.3 Formwork Selection System Validation-Secon Nile Towers Project case
study
In order to validate the formwork selection system, a real-life project is used in order to apply the
model. The project in selection is Secon Nile Towers shown in figure 97 which is a high-rise
project located in Egypt, and the general information about the project is as follows:
Figure 95: Secon Nile Tower Layout
Figure 96: Secon Nile towers Residential
tower 3d model
Figure 94: Secon Nile tower Residential Slab Post
tension stages
Figure 97: Secon Nile Tower
Owner: Secon
Designer: Space consultants
Contractor: Arabetc & SIAC JV
Contractor value: about 1 billion
Egyptian pounds
Consultant: Ehaf
Project Location: Maadi
The project is composed of 2 basements, lower ground floor built on the entire land plot which is
about 9600 m2; then there are two buildings each is 23 floors. The two buildings are a residential
building, and hotel managed by Hilton as shown in figures 95 and 96. The focus of the case
study will be on the residential building. The residential building has a post-tensioned flat slab
system that is divided into three stages as shown in figure 94. The Formwork Selection system
will be applied on stage 1, and stage 2
104
5.3.1 Secon Nile Tower-System Selected by Contractor
The system selected by the contractor was the Prop Table formwork system manufactured by
Acrow, with Main, and secondary H-20 beams. The system is formed out of the same
components of the European props; in addition to a C-Fork, Lifting Hook, and shifting trolley.
The system total cost including back proping for one floor is 1.75 Million Egyptian pounds, the
cycle time of installation for the Table formwork is 3 days. A floor plan for one the modules of
table formwork used in the project is shown in figure 98
Figure 98: Plan for one of the modules used for table formwork in Secon Nile Towers project
5.3.1.1 Project input
5.3.1.1.1 Geometry
The project data is added to the model. First, the Geometry of the building is drawn. The
Building contains some slight curves, that were approximated as seen in figure 100, to be able to
model the geometry in the best possible accuracy. The original boundaries of the building are
represented by blue colored line shown in figure 100, while the approximated boundaries in the
model are represented by red colored lines
105
Figure 99: Secon Nile Tower available and unavailable area defined
Figure 100: Secon NIle Tower Geometry Approximation
After doing so, the building is transformed to available, and un-available areas, and each is given
a number (Id) , which is the one shown in figure 99. Then the co-ordinates of each point is
obtained from AutoCad, and these co-ordinates shown in table 46 are defined in the model with
the slab thickness of each area, clear height, and live loads. Stage one, and two of residential
buildings are divided into two areas. The first area is with a slab thickness of 34 cm, and a clear
height of 2.96 m, and it has 11 un-available areas (Columns, and cores), while area 2 has a slab
thickness of 26cm, and a clear height of 3.04m and it has 14 un-available areas.
106
Table 46: Secon Nile Tower available, and un-available areas co-ordinates
Area One
X1
0
Y1
0
X2
8.6
Y2
0
X3
8.6
Y3
45
X4
0
Y4
45
X1
3.4
Y1
X2
4.4
Y2
X3
4.4
Y3
X4
3.4
Y4
X5
7.6
Y5
X6
8.6
Y6
X7
8.6
Y7
X8
7.6
Y8
X9
3.2
Y9
X10
4.5
Y10
X11
4.5
Y11
X12
3.2
Y12
X13
6.6
Y13
X14
8.6
Y14
X15
8.6
Y15
X16
6.6
Y16
0
0
1
1
0
0
1
1
8.8
8.8
9.8
9.8
9.0
9.0
10.0
10.0
X17
3.2
X18
4.5
X19
4.5
X20
3.2
X21
6.6
X22
8.6
X23
8.6
X24
6.6
X25
3.4
X26
4.4
X27
4.4
X28
3.4
X29
7.2
X30
8.4
X31
8.4
X32
7.2
Y17
Y18
Y19
Y20
Y21
Y22
Y23
Y24
Y25
Y26
Y27
Y28
Y29
Y30
Y31
Y32
17.6
17.6
18.6
18.6
10
10
19
19
27
27
28
28
26
26
1
Area 1
unavailable
areas
2
5
6
9
Area
Two
3
4
7
10
8
28
28
11
X33
3.8
Y33
X34
5.1
Y34
X35
5.1
Y35
X36
3.8
Y36
X37
7.6
Y37
X38
8.6
Y38
X39
8.6
Y39
X40
7.6
Y40
X41
4.5
Y41
X42
5.8
Y42
X43
5.8
Y43
X44
4.5
Y44
35.6
35.6
37
36.6
35
35
45
45
44
44
45
45
X11 X12 X13 X14
8.6 25.8 26 8.6
Y11 Y12 Y13 Y14
0
0
45
45
1
2
3
4
X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26
12 13.4
13
12
18
19
19
18
25
26
26
25
25
26
26
25
Y11 Y12 Y13 Y14 Y15 Y16 Y17 Y18 Y19 Y20 Y21 Y22 Y23 Y24 Y25 Y26
0
0
1
1
0
0
1
1
5
5
6
6 8.5 8.5 9.5 9.5
5
6
7
8
X27 X28 X29 X30 X31 X32 X33 X34 X35 X36 X37 X38 X39 X40 X41 X42
8.6 14.1
14 8.6
9
19
19
9
13
19
19
13
44
45
45
44
Y27 Y28 Y29 Y30 Y31 Y32 Y33 Y34 Y35 Y36 Y37 Y38 Y39 Y40 Y41 Y42
9
9
10
10
10
10
19
19
19
19
22
22
18
18
19
19
Area 2
unavailable
areas
X43
12
Y43
24
9
10
11
12
X44 X45 X46 X47 X48 X49 X50 X51 X52 X53 X54 X55 X56 X57 X58
18.5
19
12
16
18
18
16
44
45
45
44 8.6
20
20 8.6
Y44 Y45 Y46 Y47 Y48 Y49 Y50 Y51 Y52 Y53 Y54 Y55 Y56 Y57 Y58
23.7
27
27
27
27
27
27
25
25
27
27
35
35
45
45
13
14
X59 X60 X61 X62 X63 X64 X65 X66
44
45
45
44
44
45
45
44
Y59 Y60 Y61 Y62 Y63 Y64 Y65 Y66
34 34.2
35
35
43
43
44
44
107
5.3.1.2 Material Properties
The material properties that were used in the model are for Acrow Formwork H-20, S-Beam,
Timber, and the false systems considered are the European Prop,Shorebrace, and Cuplock
manufactured by Acrow. Concerning the lateral bracing, the cup lock system is braced each 3
rows, and each 3 props are braced together in these selected rows. The European prop system is
braced in both direction x, and y, and the number of props that are braced together is three, for
the shorebrace system, each two frames are braced together, and for the wood formwork system,
the bracing is done in the same manner as the European prop. All the previous data for bracing
are based on Acrow Egypt recommendation for its formwork systems.
5.3.1.3Cost-Related data
Based on data obtained from the project, the contract duration is about 3 years, 1 year of them is
allocated for the concrete works of the residential building. In order to be able to finish the
concrete work in this duration, two floors are required to be poured per month. In order to be
able to compare the selected formwork system with the table formwork used by the contractor.
Formwork material for two floors for the towers is going to be bought, in order to reduce the
conflict of the formwork removal, and post tensioning on the building cycle per floor. In order to
able to calculate the time savings based on the different systems, the maximum allowable
duration for formwork installation is 6 working days, since the wood conventional formwork is
the slowest system, the required manpower to finish the formwork installation for the slab, which
has an area of 800 m2using conventional formwork in 6 working days is 25 carpenters, 1
foreman, and 5 helpers. Using data from the project, this manpower can finish the installation of
formwork for the European Props in 3 days, Shorebrace in 4 days, and cuplock in 5 days. Since
the concrete works of the residential building is on the critical path of the project; therefore, any
early completion of the project will yield to cost savings for the indirect cost. The cost savings
per one use for the European prop will be equal to three days indirect cost savings for the project
per floor, while the shore brace will be two days indirect cost saving for the project per floor, and
the cup lock will be equal to one day indirect cost savings for the project per floor. The indirect
cost of the project for the Residential building is equal to 54,000 L.E. Based on the following
information, and the required manpower, the labor cost per day using an average daily salary of
95 L.E for the carpenter, 110 L.E for the foreman carpenter, 5 helpers with an average daily
salary of 55L.E, the daily labor cost is equal to 2760 L.E Per day, multiplying this labor cost per
108
day with the duration for formwork installation, will sum up to the total labor cost for one use for
each system. An interest rate of 12% was used, and the number of uses is based on table 47
according to Peurifoy (2006). The depreciation of each material is calculated based on the useful
life time of this material compared to the number of use per year for the material, which is 12
times for secon nile tower, since there are 23 floors, and formwork system for two floors is going
to be bought with an assumption of 10% Salvage value at the end of the material useful life. The
costs used in this case study are based on Acrow Masr 2013 Price list (Since the formwork
selection for residential building in the project was made in year 2013). It must be noted that the
maintenance cost, modification cost, Lifting & Transportation cost, Quality Cost, and Risk Cost
used in the case study is equal to zero, since in the Secon Nile towers projects, all of these factors
were considered the same for all formwork systems in selection.
Table 47: Number of uses for formwork elements (Peurifoy, 2006)
5.3.2 Optimization using Evolver 5.5
The optimization was done for each system separately using the variables, constraints, and
objective function mentioned in chapter 4. The Population size used is 1000 and cross over rate
of 0.5, and a mutation rate of 0.2, and it was observed that the average running time the model
took to optimize the system was about 45 minutes using an Acer laptop with an AMD processer,
and a 4 GB rams. Using a higher performance PC or laptop will reduce the running time. The
Evolver Watcher for each formwork system is shown in the following figures. Figure 102 shows
109
the evolver watcher for the European prop, which reached a cost of comparison equal to 131,370 L.E , after 47 minutes running time, figure 101 shows the evolver watcher for the
Shorebrace system, which reached a cost of comparison equal to -81,515 L.E , after 1 hour, and
10 minutes running time, figure 104 shows the evolver watcher for the Cuplock system, which
reached a cost of comparison equal to -25,777 L.E , after 49 minutes running time, and figure
103 the evolver watcher for the Wood formwork system, which reached a cost of comparison
equal to 28,525L.E , after 36 minutes running time
Figure 101: Evolver watcher for Shore brace system-Secon Nile Towers
Figure 102: Evolver watcher for European Prop-Secon Nile Towers
Figure 103: Evolver watcher for Wood Formwork system-Secon Nile
Towers
Figure 104: Evolver watcher for cuplock system-Secon Nile Towers
110
5.3.3 Formwork Selection System output
Table 48: Formwork Selection System Output
User Output Summary
1-Cuplock System
2-Shorebrace System
3-Europrop System
Cost for
Cost for
Cost for
(25,777)
Comparison
(81,515)
(131,371)
Comparison
Comparison
(L.E)
Rent or
Rent or
Rent or
Purchase
Purchase
Purchase
Purchase
Purchase
Purchase
Actual Cost
Actual Cost
Actual Cost of
of Rental or
of Rental or
Rental or
497,740
623,515
577,590
Purchase
Purchase
Purchase
(L.E)
(L.E)
(L.E)
Main Beam
Main Beam
Main Beam
H20
H20
H20
Material
Material
Material
(For Slab)
Secondary
Secondary
Secondary
Beam
Wood
Wood
H20
Beam
Beam
Material
Material
Material
(For Slab)
The Best False work to use for you
Europrop Formwork System
project is :
4-Wood traditional
System
Cost for
Comparison
Rent or
Purchase
Actual Cost of
Rental or
Purchase
(L.E)
Main Beam Material For Slab is :
H20
Secondary Beam Material For Slab is :
H20
Purchase or Rent
Purchase
Purchase or Rental Cost is:
623,515
L.E
The outputted decision from the model shown in table 48 based on the inputted costs including
labor cost, and in direct cost per one use is to Purchase a European prop system with Main and
Secondary H20 Beams and a Purchase cost estimate of 623,515 L.E, with a total of 1,247,030
L.E for the two floors European formwork systems for stage one and stage two. The design
outputs used for the European props are shown in table 49. It must be noted that all the
comparison costs of the formwork systems have a negative value(Cost savings), due to the
severe impact of the time saving cost resulting in in-direct cost reduction for the project, and this
is expected, since the indirect costs of a joint venture contractors like Arabtec, and SIAC is
expected to be that high.
111
28,575
Purchase
168,304
Table 49: Design Parameters for European Prop optimized design-Secon Nile Tower Project
Area One
Design Parameter for European Prop
Distance Between Secondary beams
Main Direction for Main Beam
Props Distance (X-direction)
Props Distance (Y-direction)
Main beam overlap
Secondary beam overlap
Allowable cantilever length for main beam
Main Beam Length
Secondary Beam Length
Prop Type to be used
0.44
X
1.16
1.19
0.3
0.3
0.70
2.50
2.50
E30
m
Area Two
Design Parameter for European Prop
Distance Between Secondary beams
Main Direction for Main Beam
Props Distance (X-direction)
Props Distance (Y-direction)
Main beam overlap
Secondary beam overlap
Allowable cantilever length for main beam
Main Beam Length
Secondary Beam Length
Prop Type to be used
0.45
X
1.57
1.02
0.3
0.3
0.91
3.30
3.30
E30
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
5.3.4 Comparison between the Outputted Formwork System, and the Used formwork system
in Secon Nile Towers
The outputted decision was to use the European prop system, which has exactly the same
components of the Prop table form used in Secon Nile towers project; however, the use of the
table formwork system in the project was not necessary. Although, the formwork model
developed in this research paper does not consider this type of formwork; however, still some
numerical comparison can be made between the two systems. The Table formwork will need half
the labor needed for formwork installation of the European props; therefore, based on 24 floors,
and the labor cost calculations used in this case study, the European props will have a labor cost
that is higher than the table formwork by 99,360 L.E; also, there is no need for dismantling the
table formwork, and reinstalling it; therefore, the cost of dismantling the European prop should
be added, based on 25 carpenters, 5 helpers, and 1 foreman needed to dismantle the formwork of
each floor in 1 day, the cost needed for dismantling the European prop system for the 24 floors
will be 66,240 L.E. Thus, the European prop will have an excessive labor cost equal to 165,600
112
L.E when compared to the Table formwork system. Adding this excessive labor cost to the
purchase cost of the European prop will lead to having a cost of 1,412,000 L.E for purchasing the
European prop system, and accounting for the excessive labor needed to complete the job at the
same cycle time of the table formwork, which has a purchase cost equal to 1,564,00 L.E without
the back propping elements. This means that the European prop is still a more economical
decision than using the prop table formwork for Secon Nile towers Project, although the lifting
cost, and crane capacity factors for the table formwork were not considered
5.3.5 Sensitivity of Formwork selection decision
Since the decision of using European prop formwork system, as the formwork system for stage
one and two of the residential building in Secon nile towers. It must be noted that the decision
depended to a great extent on the high productivity rate of the European prop system, and the
high indirect cost per day. The used productivity rates for the formwork system in Secon nile
tower case varied from 0.93manhour/ m2 for the Europrop, reaching to the highest value of 1.86
manhour/ m2 for the Conventional wood system, although this productivity might be low
compared to the productivity rate range specified by Peurifoy(2006), which is 0.4 to 0.8
manhour/m2 for conventional formwork systems; however these are the productivity rates used
in Secon Nile towers project. As shown from figure 105,which plots the Europorp variation in
productivity which affects labor cost, and time saving cost on the cost of comparison, and thus
the formwork system selection. From the graph below it can be concluded that as long as the
productivity rate of the labor is 1.2 manhour/m2 (about 20m2/day crew productivity), or below
the decision concerning the formwork selection system will be valid.
Cost for Comparision (L.E)
Senstivity Of Decision to Productivity Rate
varaitation for Europrop System
50,000
European Prop Productivity
0
0
0.5
1
1.5
2
Shorebrace Planned Productivity
-50,000
Cuplock Planned Productivity
-100,000
-150,000
Labor Productivity (Manhour/ m2)
Figure 105: Sensitivity of Formwork selection system outputted decision
113
Conventional Wood Planned
productvity
5.4 Formwork Selection System Application on Low income housing
5.4.1 Optimization Concept
Nowadays, there is a need for low income housing in Egypt, and due to this need many
researchers have tried to reduce the cost of low income housing, so as to make it more feasible,
and economic. One of the Researchers who tried to do so is Amr Mostafa Fathy (2015). Fathy
developed a proposed plan as the one shown in figure 106 for low income housing
Figure 106: Low income housing plan (Fathy,2015)
In fact in order to optimize the formwork system selected for this floor plan is kind of
challenging, since it has very narrow areas, and a great deal of beams, so in order to simplify the
problem, and output more accurate results instead of modeling the whole area. Each area was
considered as a separate available area, totaling up to 6 available areas as shown in figure 108,
and then the design of the slabs is optimized; moreover, the beams were divided into 4 different
categories however all of them has a depth of 60 cm as shown in figure 107. However, modeling
the plan using the position of each area will not give the most optimum result due to the spacing
grid problem shown in figure 110, where the model uses a point as its zero co-ordinates, and
creates a grid based on the props spacing. In order to tackle this problem in the most effective
way and since the slab system is solid slab system, in which each area is isolated from the other.
In other words, no area is related to the other since they are divided by beams, each area is
modeled from with zero co-ordinates starting point as shown in figure 109. Also, the beam were
optimized in a separate model alone, and was simplified to four different beam types; however
all of them are the same type (They all have the same beam depth).
114
Area Five
Area Three
Area Six
Area Four
Area One
Beam
Area two
Beam One
Beam Two
Legend
Beam Three
Beam Four
Figure 108: Low income housing Plan Areas
Figure 107: Low income housing beams plan compiled
Area Five
Area Three
Area Six
Area Four
Area
Areatwo
One
Area Six Area Three
Area Five
Area Four
Area One
Figure 110: Grid in accuracy Problem
Beam
Legend
Beam One
Beam Two
Beam Three
Beam Four
115
Figure 109: Low income Housing Modeling concept
Area two
5.4.2 Data used in optimization
The data used for optimization was the same as that used in Secon nile towers; however, the
material used for sheathing is 1*4 inch Eastern Spruce with material obtained from Nunnally
(2007). Also, the cost for comparison used is based only on the purchase cost, since the labor
cost, indirect cost, and other costs would vary from contractor to another and in the field of low
income housing, the contractor cost in direct cost is minimal. The optimization was done using a
number of uses equal to 1, and the same overall uses until disposal used in Secon nile tower case
study. A minimum clear height of 2.7 meters is assumed in the model
5.4.3 Optimization Process
For the available areas, each formwork system was optimized separately using the same
optimization parameters as Secon Nile Tower case study. As shown in figure 111 a cuplock cost
of comparison equal to 4088 L.E was obtained for available areas in 52 minutes running time, as
shown in figure 112 a Shorebrace cost of comparison equal to 4673 L.E was obtained for
available areas in 32 minutes running time, as shown in figure 113 a European prop cost of
comparison equal to 5996 L.E was obtained for available areas in 15 minutes running time, as
shown in figure 114 a Conventional wood cost of comparison equal to 2092 L.E was obtained
for available areas in 9 minutes running time. Concerning the optimization model for the beam,
since all the beams have the same design type, all of them are 60 cm in depth. The Four systems
were optimized together by minimizing the total cost of comparison for the four systems
together, and the output of the optimization was a cost of comparison equal to 7967 L.E obtained
in 12 minutes as shown in figure 115. The obtained systems was Cuplock system with main SBeam, and Secondary H-20 Beams for slabs, and Main H-20 Beam, and Secondary timber
(5cm*10cm) beam, While for the shore brace system the Main beam is S-Beam, and the
Secondary Beam is H-20, and for the beams both Main and Secondary beams are H-20.
Moreover, the European Prop system for the slab & beams used H-20 for both main and
secondary beams.
116
Figure 111: Evolver watcher-Cuplock system-available areas-low income
housing
Figure 112: Evolver watcher-Shorebrace system-available areas-low
income housing
Figure 113: Evolver watcher-European Prop-available areas-low income
housing
Figure 114: Evolver watcher-Wood formwork-available areas-low
income housing
Figure 115: Evolver watcher-All formwork systems-Beams-low income housing
117
5.4.4 Low income Housing Formwork Selection, and Design optimization
Based on the optimization output the graph shown in figure 116 was developed by changing the
number of uses per year for each system, and adding up the cost of comparison obtained from the
available area model, and the beams model
Low Income Housing Formwork Selection System
2000
Cost for Comparision (L.E)
1800
1600
1400
Cuplock
1200
Shorebrace
European Prop
1000
Conventional Wood
800
600
0
10
20
30
40
50
60
70
80
90
100 110
Number of Formwork Yearly Use
Figure 116: Formwork System Selection Vs. Number of Formwork Yearly uses
Therefore, For the proposed low income housing plan developed by Fathy(2015), if the
contractor is using the formwork system 25 times a year or less, the conventional wood
formwork will be the optimum system to use; however, if the contractor is using the formwork
more than 25 times a year, Shorebrace system with S-Beam Main Beam , and H-20 Secondary
Beam for Slabs, and a H-20 main and secondary beams for beams will be the optimum System to
use.
118
5.4.5 Conventional Wood formwork design
For the conventional wood formwork design the outputted design data from the model is shown
in table 50
Table 50: Design parameter conventional wood formwork
Conventional Wood Design Parameters
Area One
Area Four
Distance Between Secondary beams
0.44 m Distance Between Secondary beams
0.45 m
Main Direction for Main Beam
Props Distance (X-direction)
Y
Main Direction for Main Beam
1.11 m Props Distance (X-direction)
X
0.81 m
Props Distance (Y-direction)
1.25 m Props Distance (Y-direction)
1.02 m
Area Two
Distance Between Secondary beams
Area Five
0.44 m Distance Between Secondary beams
0.4
m
Main Direction for Main Beam
Props Distance (X-direction)
Y
Main Direction for Main Beam
1.45 m Props Distance (X-direction)
X
0.8
m
Props Distance (Y-direction)
1.15 m Props Distance (Y-direction)
0.94 m
Area Three
Area Six
Distance Between Secondary beams
0.4
m Distance Between Secondary beams
Main Direction for Main Beam
X
Main Direction for Main Beam
0.41 m
X
Props Distance (X-direction)
0.89 m Props Distance (X-direction)
0.83 m
Props Distance (Y-direction)
0.91 m Props Distance (Y-direction)
0.94 m
Beam
Distance Between Secondary beams
0.27 m
Main Direction for Main Beam
X
Props Distance (X-direction)
1.00 m
Props Distance (Y-direction)
1.00 m
These Design parameters were used to draw formwork plans manually for the optimized
formwork design. The Formwork Plans for the optimized formwork design for low income
housing plan is shown in the following figures.
119
Figure 117: Slab Wood Formwork Design for low income housing
Figure 118: Beams wood formwork design for low income housing
120
Table 51: Conventional Wood formwork system cost for low income housing
Conventional Wood System Cost
Slabs
Element
Length (m)
quantity
Price/unit (L.E)
2.7
70
54
Shores
2.7
30
21
Bracing
3.9
8
30
modified
13
21
2.7
22
54
Main Beams
modified
9
54
2.7
78
21
Secondary Beams
modified
8
21
3.3
200
13
Sheathing
Total Price of Conventional Wood Formwork for slabs
Beams
Element
Length (m)
quantity
Price/unit (L.E)
2.7
120
54
Shores
2.7
52
54
Main Beams
modified
2
54
modified
191
21
Secondary Beams
3.3
209
13
Sheathing
Total Price of Conventional Wood Formwork for beams
Total Price conventional wood formwork system (Low income Housing)
Total Price(L.E)
3780
630
240
273
1188
486
1638
168
2600
11,003
Total Price(L.E)
6480
2808
108
4011
2717
16,124
27,127
Using a price of 1750 per m3 for shores, and main beams, and a price of 1500 m3 for secondary
beams, bracing, and the sheathing a total cost of 27,127 L.E as shown in table 51 was obtained
for the system; however, it must be noted that the bracing against lateral concrete pressure for the
beams side sheathing is not considered in the cost. The Cost obtained by manual calculation for
the slab is 11,003 L.E, while the value obtained from the model was 11,735, which total to a 7%
overestimation in the Purchase cost of the system, which is acceptable giving the restricted area
of formwork; however, the beam cost was not compared to the system, since not all the 14 beams
were entered in the model, only 4 different types were entered, so the purchase cost is based on 4
beams only; however the value calculated by manual calculations is based on the 14 beams. It
must be noted that if a shorter beam than the 2.7 m is used, it is expected that the system
purchase cost will decrease.
5.4.6 Shorebrace formwork design
For the Shorebrace formwork design the outputted design data from the model is shown in table
52; however, the data used was modified in order to account for allowable spacing to avoid
conflict between the Shorebrace Frame for the Slab, and the Shorebrace Frame for the Beam.
This conflict affected the outputted cost as it will be shown, since the low income housing plan is
121
very narrow, and tight area, that needs special consideration for a system like the shorebrace to
be used; also, due to this requirements area 4, and area 5 was replaced with a cuplock system
instead of a shorebrace system, since it was the second economical option after the shorebrace as
it is going to be shown from the design drawings.
Table 52: Shorebrace Design Parameters outputted from the model
Shorebrace Design Parameters
Area One
Area Four
Distance Between Secondary beams
0.39 m Distance Between Secondary beams
Main Direction for Main Beam
Y
Main Direction for Main Beam
Spacing between Frames
0.40 m Spacing between Frames
Cross brace length
0.90 m Cross brace length
Area Two
Area Five
Distance Between Secondary beams
0.4 m Distance Between Secondary beams
Main Direction for Main Beam
X
Main Direction for Main Beam
Spacing between Frames
1.9 m Spacing between Frames
Cross brace length
0.90 m Cross brace length
Area Three
Area Six
Distance Between Secondary beams
0.4 m Distance Between Secondary beams
Main Direction for Main Beam
X
Main Direction for Main Beam
Spacing between Frames
1.4 m Spacing between Frames
Cross brace length
0.90 m Cross brace length
Beam
Distance Between Secondary beams
0.27 m
Main Direction for Main Beam
X
Spacing between Frames
0.60 m
Cross brace length
0.90 m
Figure 119: Beams Shorebrace plan-low income housing
122
0.5
X
0.4
0.90
m
0.4
Y
1
0.90
m
0.4
Y
1
0.90
m
m
m
m
m
m
m
Figure 120: Slab Shorebrace Formwork Design for low income housing
123
Table 53: Shorebrace system cost for low income housing
Shorebrace Cost
Slabs
Element
Length (m)
quantity
Price/unit (L.E)
Frames
25
334
U-Head
58
129
P-Head
58
97
0.9
26
50
Cross-Brace
1.2
10
55
Bracing tube
3.5
11
85
Bracing coupler
44
26
Cup lock prop
2
8
149
Cup lock Ledger
8
47
1.5
16
142.5
Main Beams(S-Beam)
2
22
190
modified
2
215
2.5
60
215
Secondary Beams
modified
18
215
Sheathing
3.3
200
13
Total Price of Shorebrace system for slabs
Beams
Element
Length (m)
quantity
Price/unit (L.E)
Frames
60
334
U-Head
120
129
P-Head
120
97
Cross-Brace
0.9
92
50
Main Beams(H-20)
2.5
54
215
Secondary Beams
modified
191
215
Sheathing
3.3
209
13
Total Price of Shorebrace system for beams
Total Price Shorebrace system (Low income Housing)
Total Price(L.E)
8350
7482
5626
1300
550
935
1144
1192
376
2280
4180
430
12900
3870
2600
53,215
Total Price(L.E)
20,040
15,480
11,640
4,600
11,610
41,065
2,717
107,152
160,367
The Price of the formwork components shown in table 53 are obtained from Acrow Masr 2013
price list, which are the same prices used in Secon Nile tower case study, and the quantity takeoff made manually. The obtained Purchase cost from the model was 60 thousand L.E for the slab
formwork, which gives an error of equal to 12% overestimated purchase cost for the shorebrace
system, this difference is due to the frame width constraint, in other words, there must be enough
space between the slab frame, and the beam, so as to allow for the Beam Shorebrace frame to be
placed, this check is not done in the model; especially that this is a special case that takes place
when a very tight area is designed using a system like the shorebrace, which has a frame width
constraint of 1.2m.
124
Chapter 6
Conclusion & Recommendations
125
6 Chapter 6: Conclusion & Recommendations
6.1 Summary & Conclusion
To conclude, Horizontal formwork selection, and design optimization is very important;
especially for projects with short life cycle for the concrete works. In these projects, materials
with long useful life should be used in order to avoid work interruptions, and cost loss due to
wrong selection of formwork system. No doubt, formwork selection systems that are expert
based are needed; especially that it can be used quickly and easily with minimal information
about the project inputted; however, expert based systems are not project tailored; in other
words, they are based on experts opinion, that might easily vary and can be inaccurate as stated
by Hanna (1989) due to “Experts conflict opinion”. After investigating the research done in
formwork Selection system, concluding the current gaps, and clearly defining the problem
statement, the following is a summary of what was performed in this research:

Developing a Flowchart for Formwork selection system: the currently used formwork
selection process in Egypt is done by requesting formwork manufacturer, at least three
manufactures, to submit their offers , these three offers are then evaluated by the contractor
based on the purchase cost of the system and the formwork cycle time. In this research, a
flow chart, including an accurate formwork selection procedure, was developed. First, the
project data including the geometry, material data, and cost data are defined in the model.
The model optimizes the design of each of the formwork systems using Genetic algorithm
optimization technique; then states the most suitable formwork system to purchase for the
project out of four communally used systems, which are Frames system, Cuplock System,
Props system, and the conventional wood formwork system with different main beam, and
secondary beam options like the H-20, metal or aluminum beams, or timber.

New variables in Formwork Design optimization: throughout the research done for
formwork design optimization several techniques and models were developed to optimize the
spacing between different formwork elements; however, there are other variables like the
joist, stringer lengths, and the direction of the stringer that have to be optimized, in order to
reach an economical design. Also, considering different bracing options for the shores used,
and identifying whether or not this bracing is more than required. None of the previously
mentioned parameters can be investigated without inputting the geometry of the desired
project. In addition, when different decking options are available increasing the spacing of
126
the members like the joists does not yield the most economical design, since at certain
spacing for the joist; other more expensive stringers will have to be used, as it was shown in
the literature review section of this research.

Developing Cost for comparison for the Formwork Selection system: one of the most
important aspects of this research is the cost equation used in comparison, which considers
all the factors affecting formwork selection. As Hanna (1999) stated that the factors
affecting formwork selection are slab type, lateral load supporting system, building shape,
concrete finish, speed of construction, area practice, weather conditions, site characteristics,
hoisting equipment, home office support, and supporting yard facility. Since, the cost
equation used for comparison in this research includes the purchase cost calculation, which
accounts for the slab type, lateral load supporting system, building shape parameters, and
concrete finish factors. The hoisting equipment and site characteristics factors are included in
the lifting & transportation costs, while the speed of construction is accounted for in the time
savings costs. Moreover, the area practice factor is reflected as labor cost. Finally, the home
office support, supporting yard facility and weather conditions is defined as risk costs.
Therefore, the equation used for comparison in the research includes all the formwork
selection parameters mentioned in the literature. Most importantly the cost equation used in
this research considers the time value of money, and the number of uses per year, and useful
life of the formwork material, which are parameters that was overlooked in previous
formwork selection models.

Formulating a model that performs both Formwork Design optimization, and Selection
system for regularly shaped buildings: one of the most important aspects of the research
done is the development of a model, that enables the user to get an optimized design for the
selected formwork system for his project out of four formwork systems; in addition to
providing the user with all the calculations that led to that selection. This will aid the user in
case he wants to check any of the selection parameters, and make sure in is done in the most
accurate way that suits his project. Although the model was developed for regularly shaped
buildings; however, it was successfully applied on, using minimal approximations, part of the
residential building in Secon Nile tower project, which is a slightly curved building. It was
highlighted that although the European prop was the highest purchase cost for the project, it
127
was most appropriate formwork system for Secon Nile tower project due to the high indirect
cost included in the project, and the high productivity of the European prop system.

Outputting quantity take-off, and cost estimate with reasonable accuracy: the model was
compared with manual quantity take-offs. The quantity of the materials used was estimated
with an accuracy of more than 89%. The lowest accuracy obtained when solid slab system
that had a great deal of beams, and narrow areas were optimized using the model.

Performing Formwork selection system and design optimization for low income
housing: the model was applied on an untraditional problem of the low income housing plan
developed by Fathy (2015). The most feasible system to be used was identified depending on
the number of uses per year. The conclusion was that for number of uses less than 25 per
year, the conventional wood formwork is the most economical system, if the number of uses
is more than 25 uses per year; the shorebrace formwork is the most economical system.
Moreover, formwork design drawings were developed for both wood conventional formwork
system, and shorebrace system based on the model outputted design parameters.
6.2 Research outcomes & Contributions
The following points summarize the contribution of this research to the ongoing research of
Formwork selection system, and design optimization:

Developing a formwork selection system concept, and flowchart that uses different
project inputs, and considers them while selecting the formwork system

Proving that the formwork system with the least purchase cost is not necessarily the most
cost-effective formwork system to used

Highlighting the importance of formwork selection system; especially in Egypt where
formwork selection is often an overlooked aspect by decision maker in different projects.

Developing simple algorithm using an excel mode, and quantity take-off checks that can
create an automated quantity take-off for formwork components with an reasonable
accuracy

Presenting the cost of comparison equation that involves all the parameters affecting
formwork selection.

Presenting an optimized formwork design for conventional wood, and shorebrace
systems for low income housing
128

Introducing a new technique of formwork selection system rather than the Expert based
systems developed previously; therefore, opening up new research gap for formwork
selection as its going to be discussed in the following section.
6.3 Recommendations
Despite the ability of the proposed model to fill the gap in the literature, there are still several
aspects that need to be developed and improved for enhancement and improvement for more
efficient and accurate results concerning formwork selection. Below is a list of recommendations
for future researchers and applicators:

Develop a formwork selection system for irregularly shaped building

Adding up new formwork system like table formwork, Slabs panels like Sky deck
formwork system developed by Peri

Use Dynamic programming instead of Evolutionary algorithm which has the
disadvantage of giving a near optimum solution; however developing a dynamic
programming model will decrease the processing time needed, and will facilitate the
formwork selection procedure, and create a better user interface.

Creating a formwork selection system for Stairs

Formulating a model that optimize the use of the sheathing material, whether it is
plywood or timber, and provides the least possible waste for the sheathing

Develop a formwork design code in Egypt

Develop formulas for Formwork lateral bracing design, and the effect of dynamic loading
on the formwork systems, and incorporate them in the developed model in this research
paper.

Use Graphical visualization software Like AutoCad in order to obtain an automatically
generated formwork design for the project
129
6 References
ACROW Formwok & Scaffolding | Home. (n.d.). Retrieved April 24, 2016, from
http://acrow.co/public/index.php/Home
Alexander, A. (2003). Chapter 4/Design and Construction of Concrete Formwork. In W. F. Chen
& J. Y. Richard Liew (Eds.), The Civil Engineering Handbook-Second Edition. CRC
Press LCC.
Blickle, T. (1967). Theory of evolutionary algorithms and application to system synthesis.
Germany: Universit y of Saarbrucken.
Construction Week. (2013, March 9).Top of the formworkers. Retrieved April 24, 2016, from
http://www.constructionweekonline.com/article-21296-top-of-the-formworkers/
Doka Group. (n.d.). Retrieved April 24, 2016, from https://www.doka.com/en/index
Elbeltagi, E., Hosny, O. A., Elhakeem, A., Abd-Elrazek, M. E., & Abdullah, A. (2011).
Selectionof slab formwork system using fuzzy logic. Construction Management and
Economics, 29(7), 659-670.
Fathy, A. M. (2015). OPTIMUM DESIGN OF RC AFFORDABLE HOUSING.
Master’s Thesis.The American University in Cairo.
Hanna, A. S. (1999). Concrete formwork systems. New York: Marcel Dekker.
Hanna, A., &Senouci, A. (1995). Design Optimization of Concrete-Slab Forms. Journal Of
Construction Engineering And Management, 121(2), 215-221.
Hanna, A. (1989). An interactive knowledge based formwork selection system for buildings.
Report of research Sponsoered by the consortium for the advancement of building
sciences (CABS). The Pennsylvania state university.
Hanna, A., Willenbrock, J., &Sanvido, V. (1992). Knowledge Acquisition and Development
for Formwork Selection System. Journal Of Construction Engineering And Management,
118(1), 179-198.
Haidar, A., Naoum, S., Howes, R., and Tah, J. (1999). "Genetic Algorithms Application
and Testing for Equipment Selection." J. Constr. Eng. Manage., 10.1061/(ASCE)07339364(1999)125:1(32), 32-38.
Jaśkowski, P. and Sobotka, A. (2006). "Scheduling Construction Projects Using
130
Evolutionary Algorithm." J. Constr. Eng. Manage., 10.1061/(ASCE)07339364(2006)132:8(861), 861-870.
Kamarthi, S. V., Sanvido, V. E., and Kumara, S. R. (1992). “Neuroform—
Neural network system for vertical formwork selection.” J. Comput. Civ. Eng., 6(2),
178–193.
Kim, T., Lim, H., Lee, U., Cha, M., Cho, H., & Kang, K. (2012). Advanced formwork
method integrated with a layout planning model for tall building construction. Canadian
Journal Of Civil Engineering, 39(11), 1173-1183.
Lin, C., Hsie, M., Hsiao, W., Wu, H., and Cheng, T. (2012). "Optimizing the Schedule of
Dispatching Earthmoving Trucks through Genetic Algorithms and Simulation." J.
Perform. Constr. Facil., 10.1061/(ASCE)CF.1943-5509.0000219, 203-211.
Nassar, K., & Aly, E. A. (2012). Automated Planning and Design of Formwork for Freeform
Shell Structures. Construction Research Congress 2012.
Nunnally, S. W. (2007). Chapter 13/Concrete Form Design. In Construction Methods and
Managment (Seventh ed., pp. 371-401). Pearson Education International.
PERI Group. (n.d.). Retrieved April 24, 2016, from http://www.peri.com/en
Peurifoy, R. L., & Oberlender, G. D. (2011). Formwork for concrete structures (Fourth ed.).
New York: McGraw-Hill.
Peurifoy, R. L., Schexnayder, C. J., & Shapira, A. (2006). Chapter 22/Forming Systems. In
Construction Planning, Equipnment and Methods (Seventh edition ed., pp. 703-750).
McGraw-Hill.
Que, B. (2002). "Incorporating Practicability into Genetic Algorithm-Based Time-Cost
Optimization." J. Constr. Eng. Manage., 10.1061/(ASCE)0733-9364(2002)128:2(139),
139-143.
Radford, A., & Gero, J. S. (1988). Design by optimization in architecture, building, and
construction. New York: Van Nostrand Reinhold.
Rutten, D. (2010). “Evolutionary Principles applied to Problem Solving”. Grasshopper3D online
blog. Accessed May, 2016.
<http://www.grasshopper3d.com/profiles/blogs/evolutionary-principles>
Shin, Y., Kim, T., Cho, H., & Kang, K. (2012). A formwork method selection model based on
boosted decision trees in tall building construction. Automation In Construction, 23, 4754.
Tabassum, M., & Mathew, K. (2014). A Genetic Algorithm Analysis Towards Optimization
Solutions. IJDIWC International Journal of Digital Information and Wireless Communications,
4(1), 124-142. doi:10.17781/p001091
The DecisionTools Suite: Risk & Decision Analysis Software for Excel - Palisade. (n.d.).
Retrieved May 15, 2016, from http://www.palisade.com/decisiontools_suite/
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Appendix
132
Visual Basic Code for Graphical interface
Sheet 1
Sub SelectAllRectangles(
Dim shpTemp As Shape
Dim i As Integer
Dim a As Integer
Dim b As Integer
Dim c As Integer
Dim d As Integer
Dim e As Integer
Dim f As Integer
Dim g As Integer
Dim h As Integer
Dim k As Integer
Dim L As Integer
Dim m As Integer
Dim n As Integer
i=1
a=1
b=1
c=1
d=1
e=1
f=1
g=1
h=1
k=1
L=1
m=1
n=1
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType =
msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(0, 0,
255) Then
Cells(i, 1) = shpTemp.Height
Cells(i, 2) = shpTemp.Width
Cells(i, 3) = shpTemp.Left
Cells(i, 4) = shpTemp.Top
i=i+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType =
msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(255,
0, 0) Then
Cells(a, 5) = shpTemp.Height
Cells(a, 6) = shpTemp.Width
Cells(a, 7) = shpTemp.Left
Cells(a, 8) = shpTemp.Top
a=a+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType =
msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(255,
255, 0) Then
Cells(b, 9) = shpTemp.Height
Cells(b, 10) = shpTemp.Width
Cells(b, 11) = shpTemp.Left
Cells(b, 12) = shpTemp.Top
b=b+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
Sheet 2
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType = msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(0, 255, 0) Then
Cells(c, 13) = shpTemp.Height
Cells(c, 14) = shpTemp.Width
Cells(c, 15) = shpTemp.Left
Cells(c, 16) = shpTemp.Top
c=c+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType = msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(0, 0, 0) Then
Cells(d, 17) = shpTemp.Height
Cells(d, 18) = shpTemp.Width
Cells(d, 19) = shpTemp.Left
Cells(d, 20) = shpTemp.Top
d=d+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType = msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(0, 255, 255) Then
Cells(e, 21) = shpTemp.Height
Cells(e, 22) = shpTemp.Width
Cells(e, 23) = shpTemp.Left
Cells(e, 24) = shpTemp.Top
e=e+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType = msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(255, 0, 255) Then
Cells(f, 25) = shpTemp.Height
Cells(f, 26) = shpTemp.Width
Cells(f, 27) = shpTemp.Left
Cells(f, 28) = shpTemp.Top
f=f+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType = msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(255, 255, 255)
Then
Cells(g, 29) = shpTemp.Height
Cells(g, 30) = shpTemp.Width
Cells(g, 31) = shpTemp.Left
Cells(g, 32) = shpTemp.Top
g=g+1
End If
End If
End If
Next
For Each shpTemp In ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType = msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB = RGB(100, 100, 100)
Then
Cells(h, 33) = shpTemp.Height
Cells(h, 34) = shpTemp.Width
133
Sheet 3
Cells(h, 35) = shpTemp.Left
Cells(h, 36) = shpTemp.Top
h=h+1
End If
End If
End If
Next
For Each shpTemp In
ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType =
msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB =
RGB(200, 200, 200) Then
Cells(k, 37) = shpTemp.Height
Cells(k, 38) = shpTemp.Width
Cells(k, 39) = shpTemp.Left
Cells(k, 40) = shpTemp.Top
k=k+1
End If
End If
End If
Next
For Each shpTemp In
ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType =
msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB =
RGB(50, 150, 0) Then
Cells(L, 41) = shpTemp.Height
Cells(L, 42) = shpTemp.Width
Cells(L, 43) = shpTemp.Left
Cells(L, 44) = shpTemp.Top
L=L+1
End If
End If
End If
Next
For Each shpTemp In
ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType =
msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB =
RGB(50, 100, 150) Then
Cells(m, 45) = shpTemp.Height
Cells(m, 46) = shpTemp.Width
Cells(m, 47) = shpTemp.Left
Cells(m, 48) = shpTemp.Top
m=m+1
End If
End If
End If
Next
For Each shpTemp In
ActiveSheet.Shapes
If shpTemp.Type = msoAutoShape Then
If shpTemp.AutoShapeType =
msoShapeRectangle Then
If shpTemp.Fill.ForeColor.RGB =
RGB(150, 100, 50) Then
Cells(n, 49) = shpTemp.Height
Cells(n, 50) = shpTemp.Width
Cells(n, 51) = shpTemp.Left
Cells(n, 52) = shpTemp.Top
n=n+1
End If
End If
End If
Next
End Sub