Formwork for Concrete Structures
Formwork for Concrete Structures
Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Abbreviations and Symbols . . . . . . . . . . . . . . . . . . . . . xxi
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Purpose of This Book . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Safety of Formwork . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Economy of Formwork . . . . . . . . . . . . . . . . . . . . . . . . 2
Allowable Unit Stresses in Formwork Material . . . 2
Care of Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Patented Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Arrangement of This Book . . . . . . . . . . . . . . . . . . . . . 3
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Economy of Formwork . . . . . . . . . . . . . . . . . . . . . . . . 7
Background Information . . . . . . . . . . . . . . . . . . . . . . . 7
Impact of Structural Design on Formwork Costs . . . 7
Suggestions for Design . . . . . . . . . . . . . . . . . . . . . . . . 9
Design Repetition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Dimensional Standards . . . . . . . . . . . . . . . . . . . . . . . . 10
Dimensional Consistency . . . . . . . . . . . . . . . . . . . . . . 11
Economy of Formwork and Sizes of Concrete
Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Beam and Column Intersections . . . . . . . . . . . . . . . . 12
Economy in Formwork and Sizes of
Concrete Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Economy in Making, Erecting, and
Stripping Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Removal of Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Building Construction and Economy . . . . . . . . . . . . 16
Economy in Formwork and Overall Economy . . . . 19
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3 Pressure of Concrete on Formwork . . . . . . . . . . . . . 21
Behavior of Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Lateral Pressure of Concrete on Formwork . . . . . . . 22
Lateral Pressure of Concrete on Wall Forms . . . . . . 23
Example 3-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Example 3-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Example 3-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Relationship between Rate of Fill, Temperature,
and Pressure for Wall Forms . . . . . . . . . . . . . . . . . 28
Lateral Pressure of Concrete on Column Forms . . . 31
Example 3-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Example 3-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Example 3-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Relationship between Rate of Fill, Temperature,
and Pressure for Column Forms . . . . . . . . . . . . . . 33
Graphical Illustration of Pressure Equations for
Walls and Columns . . . . . . . . . . . . . . . . . . . . . . . . . 33
Effect of Weight of Concrete on Pressure . . . . . . . . . 36
Vertical Loads on Forms . . . . . . . . . . . . . . . . . . . . . . . 36
Example 3-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Example 3-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Example 3-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Placement and Consolidation of Freshly Placed
Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Wind Loads on Formwork Systems . . . . . . . . . . . . . . 39
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4 Properties of Form Material . . . . . . . . . . . . . . . . . . . 41
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Properties of Lumber . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Allowable Stresses of Lumber . . . . . . . . . . . . . . . . . . 44
Adjustment Factor C
for Load-Duration . . . . . . . . . 46
Adjustment Factors C
for Moisture Content . . . . . 46
Adjustment Factor C
for Beam Stability . . . . . . . . . 51
Adjustment Factor C
for Column Stability . . . . . . . 51
Adjustment Factors C
for Flat Use . . . . . . . . . . . . . . 52
Adjustment Factors C
for Bearing Area . . . . . . . . . . . 52
Application of Adjustment Factors . . . . . . . . . . . . . . 53
Example 4-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Example 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Plywood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Allowable Stresses for Plywood . . . . . . . . . . . . . . . . . 55
Plyform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
High-Density Overlaid Plyform . . . . . . . . . . . . . . . . . 60
Equations for Determining the Allowable
Pressure on Plyform . . . . . . . . . . . . . . . . . . . . . . . . 60
Allowable Pressure Based on Fiber Stress in
Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Allowable Pressure Based on Bending Defl ection . . . . 63
Allowable Pressure Based on Shear Stress . . . . . . . . 63
Allowable Pressure Based on Shear Defl ection . . . . 63
Tables for Determining the Allowable Concrete
Pressure on Plyform . . . . . . . . . . . . . . . . . . . . . . . . 64
Maximum Spans for Lumber Framing Used to
Support Plywood . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Use of Plywood for Curved Forms . . . . . . . . . . . . . . 66
Hardboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Fiber Form Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Steel Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Aluminum Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Plastic Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Form Liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Nails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Withdrawal Resistance of Nails . . . . . . . . . . . . . . . . . 75
Lateral Resistance of Nails . . . . . . . . . . . . . . . . . . . . . 75
Toe-Nail Connections . . . . . . . . . . . . . . . . . . . . . . . . . 77
Connections for Species of Wood for Heavy
Formwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Lag Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Withdrawal Resistance of Lag Screws . . . . . . . . . . . 78
Lateral Resistance of Lag Screws . . . . . . . . . . . . . . . . 79
Timber Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Split-Ring Connectors . . . . . . . . . . . . . . . . . . . . . . . . . 82
Shear-Plate Connectors . . . . . . . . . . . . . . . . . . . . . . . . 83
Split-Ring and Shear-Plate Connectors in
End Grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Penetration Requirements of Lag Screws . . . . . . . . . 84
Form Ties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Concrete Anchors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
5 Design of Wood Members for Formwork . . . . . . . . 87
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Arrangement of Information in This Chapter . . . . . 87
Lumber versus Timber Members . . . . . . . . . . . . . . . . 88
Loads on Structural Members . . . . . . . . . . . . . . . . . . 89
Equations Used in Design . . . . . . . . . . . . . . . . . . . . . . 89
Analysis of Bending Moments in Beams with
Concentrated Loads . . . . . . . . . . . . . . . . . . . . . . . . 90
Analysis of Bending Moments in Beams with
Uniformly Distributed Loads . . . . . . . . . . . . . . . . 91
Bending Stress in Beams . . . . . . . . . . . . . . . . . . . . . . . 92
Stability of Bending Members . . . . . . . . . . . . . . . . . . 93
Examples of Using Bending Stress Equations for
Designing Beams and Checking Stresses
in Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Example 5-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Example 5-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Example 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Horizontal Shearing Stress in Beams . . . . . . . . . . . . . 98
Example 5-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Example 5-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Modifi ed Method of Determining the Unit Stress in
Horizontal Shear in a Beam . . . . . . . . . . . . . . . . . . 100
Example 5-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Example 5-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Defl ection of Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Defl ection of Beams with Concentrated Loads . . . . 105
Defl ection of Single-Span Beams with
Concentrated Loads . . . . . . . . . . . . . . . . . . . . . . . . 106
Example 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Multiple-Span Beam with Concentrated Loads . . . . 108
Defl ection of Beams with Uniform Loads . . . . . . . . . 109
Single-Span Beams with Uniformly Distributed
Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Example 5-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Defl ection of Multiple-Span Beams with Uniformly
Distributed Loads . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Table for Bending Moment, Shear, and Defl ection for
Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Calculating Defl ection by Superposition . . . . . . . . . 113
Example 5-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Example 5-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Allowable Span Length Based on Moment, Shear, or
Defl ection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Allowable Span Length for Single-Span Members
with Uniformly Distributed Loads . . . . . . . . . . . . 116
Allowable Span Length for Multiple-Span Members
with Uniformly Distributed Loads . . . . . . . . . . . . 116
Stresses and Defl ection of Plywood . . . . . . . . . . . . . . 117
Allowable Pressure on Plywood Based on
Bending Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Example 5-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Example 5-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Example 5-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Allowable Pressure on Plywood Based on Rolling
Shear Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Example 5-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Allowable Pressure on Plywood Based on
Defl ection Requirements . . . . . . . . . . . . . . . . . . . . 123
Allowable Pressure on Plywood due to Bending
Defl ection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Example 5-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Allowable Pressure on Plywood Based on
Shear Defl ection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Example 5-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Tables of Equations for Calculating Allowable
Span Lengths for Wood Beams and
Plywood Sheathing . . . . . . . . . . . . . . . . . . . . . . . . . 127
Compression Stresses and Loads on Vertical Shores . . . . 127
Example 5-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Table for Allowable Loads on Wood Shores . . . . . . . 132
Bearing Stresses Perpendicular to Grain . . . . . . . . . 132
Design of Forms for a Concrete Wall . . . . . . . . . . . . . 135
Lateral Pressure of Concrete on Forms . . . . . 136
Plywood Sheathing to Resist Pressure from
Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Studs for Support of Plywood . . . . . . . . . . . . 138
Wales for Support of Studs . . . . . . . . . . . . . . . 140
Strength Required of Ties . . . . . . . . . . . . . . . . 142
Design Summary of Forms for Concrete Wall . . . . 143
Minimum Lateral Force for Design of Wall Form
Bracing Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Bracing for Wall Forms . . . . . . . . . . . . . . . . . . . . . . . . 144
Example 5-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Example 5-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Design of Forms for a Concrete Slab . . . . . . . . . . . . . 149
Loads on Slab Forms . . . . . . . . . . . . . . . . . . . . 150
Plywood Decking to Resist Vertical Load . . . . 151
Joists for Support of Plywood . . . . . . . . . . . . . 152
Stringers for Support of Joists . . . . . . . . . . . . . 154
Shores for Support of Stringers . . . . . . . . . . . 156
Minimum Lateral Force for Design of Slab Form
Bracing Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Minimum Time for Forms and Supports to
Remain in Place . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Minimum Safety Factors for Formwork
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
6 Shores and Scaffolding . . . . . . . . . . . . . . . . . . . . . . . 163
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Shores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
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Wood Post Shores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Patented Shores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Ellis Shores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Symons Shores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Site Preparation for Shoring . . . . . . . . . . . . . . . . . . . . 170
Selecting the Size and Spacing of Shores . . . . . . . . . 170
Tubular Steel Scaffolding Frames . . . . . . . . . . . . . . . . 174
Accessory Items for Tubular Scaffolding . . . . . . . . . 177
Steel Tower Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Safety Practices Using Tubular Scaffolding . . . . . . . 179
Horizontal Shores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Shoring Formwork for Multistory Structures . . . . . 182
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
7 Failures of Formwork . . . . . . . . . . . . . . . . . . . . . . . . . 185
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Causes of Failures of Formwork . . . . . . . . . . . . . . . . 185
Forces Acting on Vertical Shores . . . . . . . . . . . . . . . . 186
Force Produced by Concrete Falling on a Deck . . . . 187
Example 7-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Motor-Driven Concrete Buggies . . . . . . . . . . . . . . . . 190
Impact Produced by Motor-Driven Concrete
Buggies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Design of Formwork to Withstand Dynamic
Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Examples of Failure of Formwork and Falsework . . . . 193
Prevention of Formwork Failures . . . . . . . . . . . . . . . 194
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
8 Forms for Footings . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Forms for Foundation Walls . . . . . . . . . . . . . . . . . . . . 197
Example 8-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
Procedure for Erection of Forms for Footings . . . . . 202
Forms for Grade Beams . . . . . . . . . . . . . . . . . . . . . . . . 204
Forms for Concrete Footings . . . . . . . . . . . . . . . . . . . . 204
Additional Forms for Concrete Footings . . . . . . . . . 205
Forms for Stepped Footings . . . . . . . . . . . . . . . . . . . . 207
Forms for Sloped Footings . . . . . . . . . . . . . . . . . . . . . 208
Forms for Round Footings . . . . . . . . . . . . . . . . . . . . . 208
Placing Anchor Bolts in Concrete Foundations . . . . 210
9 Forms for Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Defi nition of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
Designing Forms for Concrete Walls . . . . . . . . . . . . . 213
C o n t e n t s xi
Physical Properties and Allowable Stresses for
Lumber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Physical Properties and Allowable Stresses for
Plyform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Table of Equations for Calculating Allowable
Span Lengths for Wood Beams and
Plywood Sheathing . . . . . . . . . . . . . . . . . . . . . . . . . 215
Design of Forms for a Concrete Wall . . . . . . . . . . . . . 220
Lateral Pressure of Concrete on Forms . . . . . 222
Plyform Sheathing to Resist Pressure
from Concrete . . . . . . . . . . . . . . . . . . . . . . . . 222
Summary of Allowable Span Lengths for the
Sheathing . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Studs for Support of Plyform . . . . . . . . . . . . . 225
Bearing Strength between Studs and Wale . . . . 226
Size of Wale Based on Selected 24 in.
Spacing of Studs . . . . . . . . . . . . . . . . . . . . . . 227
Strength Required of Ties . . . . . . . . . . . . . . . . 229
Results of the Design of the Forms for the
Concrete Wall . . . . . . . . . . . . . . . . . . . . . . . . 229
Tables to Design Wall Forms . . . . . . . . . . . . . . . . . . . . 230
Calculating the Allowable Concrete Pressure on
Plyform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Allowable Pressure Based on Fiber Stress in
Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Allowable Pressure Based on Bending Defl ection . . . . 234
Allowable Pressure Based on Shear Stress . . . . . . . . 235
Allowable Pressure Based on Shear Defl ection . . . . 235
Maximum Spans for Lumber Framing Used to
Support Plywood . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Using Tables to Design Forms . . . . . . . . . . . . . . . . . . 240
Forms for Walls with Batters . . . . . . . . . . . . . . . . . . . . 240
Forms for Walls with Offsets . . . . . . . . . . . . . . . . . . . 241
Forms for Walls with Corbels . . . . . . . . . . . . . . . . . . . 242
Forms for Walls with Pilasters and Wall Corners . . . . 243
Forms for Walls with Counterforts . . . . . . . . . . . . . . 243
Forms for Walls of Circular Tanks . . . . . . . . . . . . . . . 244
Form Ties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Snap Ties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Coil Ties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Taper Ties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Coil Loop Inserts for Bolt Anchors . . . . . . . . . . . . . . 250
Prefabricated Wood Form Panels . . . . . . . . . . . . . . . . 251
Commercial, or Proprietary, Form Panels . . . . . . . . . 253
Gates Single-Waler Cam-Lock System . . . . . . . . . . . 253
xii C o n t e n t s
Forms for Pilasters and Corners . . . . . . . . . . . . . . . . . 255
Ellis Quick-Lock Forming System . . . . . . . . . . . . . . . 257
Jahn System for Wall Forms . . . . . . . . . . . . . . . . . . . . 260
Forms for a Concrete Wall Requiring a Ledge
for Brick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
Forms for a Stepped Concrete Wall . . . . . . . . . . . . . . 269
Modular Panel Systems . . . . . . . . . . . . . . . . . . . . . . . 269
Hand Setting Modular Panels . . . . . . . . . . . . . . . . . . 272
Gang-Forming Applications . . . . . . . . . . . . . . . . . . . . 272
Gang Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
Forms for Curved Walls . . . . . . . . . . . . . . . . . . . . . . . . 276
Jump Form System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
Self-Lifting Wall-Forming System . . . . . . . . . . . . . . . 280
Insulating Concrete Forms . . . . . . . . . . . . . . . . . . . . . 281
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
10 Forms for Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
Pressure on Column Forms . . . . . . . . . . . . . . . . . . . . . 283
Designing Forms for Square or Rectangular
Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
Sheathing for Column Forms . . . . . . . . . . . . . . . . . . . 286
Maximum Spacing of Column Clamps Using S4S
Lumber Placed Vertical as Sheathing . . . . . . . . . . 286
Example 10-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Plywood Sheathing with Vertical Wood Battens for
Column Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
Tables for Determining the Maximum Span
Length of Plyform Sheathing . . . . . . . . . . . . . . . . . 290
Maximum Spacing of Column Clamps Using
Plyform with Vertical Wood Battens . . . . . . . . . . . 292
Example 10-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
Column Clamps for Column Forms . . . . . . . . . . . . . 296
Design of Wood Yokes for Columns . . . . . . . . . . . . . 296
Example 10-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
Example 10-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
Steel Column Clamps with Wedges . . . . . . . . . . . . . 300
Example 10-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Concrete Column Forms with Patented Rotating
Locking Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
Column Forms Using Jahn Brackets and
Cornerlocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Modular Panel Column Forms . . . . . . . . . . . . . . . . . . 306
Adjustable Wraparound Column Forms . . . . . . . . . . 308
All-Metal Forms for Rectangular Forms . . . . . . . . . . 308
C o n t e n t s xiii
Fiber Tubes for Round Columns . . . . . . . . . . . . . . . . 311
Steel Forms for Round Columns . . . . . . . . . . . . . . . . 312
One-Piece Steel Round Column Forms . . . . . . . . . . . 314
Plastic Round Column Forms Assembled in
Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
Spring-Open Round Fiberglass Forms . . . . . . . . . . . 316
One-Piece Round Fiberglass Column Forms . . . . . . 317
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
11 Forms for Beams and Floor Slabs . . . . . . . . . . . . . . . 319
Concrete Floor Slabs . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
Safety of Slab-Forming Systems . . . . . . . . . . . . . . . . . 320
Loads on Concrete Slabs . . . . . . . . . . . . . . . . . . . . . . . 320
Defi nition of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Design of Forms for Concrete Slabs . . . . . . . . . . . . . . 322
Spacing of Joists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
Example 11-1 . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Use of Tables to Determine Maximum Spacing
of Joists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Size and Span Length of Joists . . . . . . . . . . . . . . . . . . 327
Example 11-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Example 11-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Use of Tables to Determine the Maximum Spans for
Lumber Framing Used to Support Plywood . . . . 332
Stringers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
Ledgers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
Forms for Flat-Slab Concrete Floors . . . . . . . . . . . . . 338
Forms for Concrete Beams . . . . . . . . . . . . . . . . . . . . . 340
Spacing of Shores under Beam Bottoms . . . . . . . . . . 341
Example 11-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
Example 11-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
Example 11-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 346
Forms for Exterior Beams . . . . . . . . . . . . . . . . . . . . . . 348
Form Details for Beams Framing into Girders . . . . . 349
Suspended Forms for Concrete Slabs . . . . . . . . . . . . 350
Designing Forms for Concrete Slabs . . . . . . . . . . . . . 351
Design of Formwork for Flat-Slab Concrete Floor
with Joists and Stringers . . . . . . . . . . . . . . . . . . . . . 353
Loads on Slab Forms . . . . . . . . . . . . . . . . . . . . 354
Plywood Decking to Resist Vertical Load . . . 354
Joists for Support of Plyform . . . . . . . . . . . . . 356
Stringers for Support of Joists . . . . . . . . . . . . . 358
Shores for Support of Stringers . . . . . . . . . . . 360
Design Summary of Forms for Concrete
Slab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
xiv C o n t e n t s
Minimum Lateral Force for Design of
Slab Form–Bracing Systems . . . . . . . . . . . . . . . . . . 363
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364
12 Patented Forms for Concrete Floor Systems . . . . . 365
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Ceco Flangeforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Adjustable Steel Forms . . . . . . . . . . . . . . . . . . . . . . . . 366
Ceco Longforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367
Ceco Steeldomes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369
Ceco Fiberglassdomes . . . . . . . . . . . . . . . . . . . . . . . . . 370
Ceco Longdomes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
Plastic Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
Corrugated-Steel Forms . . . . . . . . . . . . . . . . . . . . . . . 373
Cellular-Steel Floor Systems . . . . . . . . . . . . . . . . . . . . 373
Selecting the Proper Panel Unit for Cellular-Steel
Floor Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Horizontal Shoring . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
13 Forms for Thin-Shell Roof Slabs . . . . . . . . . . . . . . . 381
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381
Geometry of a Circle . . . . . . . . . . . . . . . . . . . . . . . . . . 381
Example 13-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 382
Locating Points on a Circle . . . . . . . . . . . . . . . . . . . . . 383
Elevations of Points on a Circular Arch . . . . . . . . . . 385
Example 13-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
Forms for Circular Shell Roofs . . . . . . . . . . . . . . . . . . 386
Design of Forms and Centering for a Circular
Shell Roof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
Space the Joists . . . . . . . . . . . . . . . . . . . . . . . . . 387
Space the Ribs . . . . . . . . . . . . . . . . . . . . . . . . . 388
Design the Ribs . . . . . . . . . . . . . . . . . . . . . . . . 388
Determine the Load on the Shores . . . . . . . . 390
Determine the Elevations of the Top of
the Decking . . . . . . . . . . . . . . . . . . . . . . . . . 391
Determine the Slope of the Decking at the
Outer Edges . . . . . . . . . . . . . . . . . . . . . . . . . 391
Centering for Shell Roofs . . . . . . . . . . . . . . . . . . . . . . . 391
Use of Trusses as Centering . . . . . . . . . . . . . . . . . . . . 392
Decentering and Form Removal . . . . . . . . . . . . . . . . 394
14 Forms for Architectural Concrete . . . . . . . . . . . . . . . 395
Forms for Architectural versus Structural
Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395
Concrete Coloring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
C o n t e n t s xv
Stained Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
Stamped Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
Form Liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
Sealing Form Liner Joints . . . . . . . . . . . . . . . . . . . . . . 399
Smooth-Surfaced Concrete . . . . . . . . . . . . . . . . . . . . . 399
Hardboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
Wetting and Oiling Forms . . . . . . . . . . . . . . . . . . . . . . 400
Nails for Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400
Form Ties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400
Construction Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
Detailing Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402
Order of Erecting Forms for a Building . . . . . . . . . . . 402
Order of Stripping Forms . . . . . . . . . . . . . . . . . . . . . . 405
Wood Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
Plaster Waste Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
Plastic Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408
Metal Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408
Forms for Corners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410
Forms for Parapets . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
Forms for Roof Members . . . . . . . . . . . . . . . . . . . . . . . 411
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413
15 Slipforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
The Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Sheathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418
Wales or Ribs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418
Yokes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418
Working Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
Suspended Scaffolding . . . . . . . . . . . . . . . . . . . . . . . . 419
Form Jacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
Operation of Slipforms . . . . . . . . . . . . . . . . . . . . . . . . 422
Constructing a Sandwich Wall . . . . . . . . . . . . . . . . . . 422
Silos and Mills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Tall Bridge Piers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424
Towers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425
Concrete Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 426
Linings for Shafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428
Slipforms for Special Structures . . . . . . . . . . . . . . . . . 429
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430
16 Forms for Concrete Bridge Decks . . . . . . . . . . . . . . 431
Wood Forms Suspended from Steel Beams . . . . . . . 431
Example 16-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 431
Wood Forms for Deck Slab with Haunches . . . . . . . 437xvi
Wood Forms for Deck Slab Suspended from
Concrete Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438
Forms for Overhanging Deck Constructed on
Exterior Bridge Beams . . . . . . . . . . . . . . . . . . . . . . . 438
Deck Forms Supported by Steel Joists . . . . . . . . . . . . 439
Example 16-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 444
Deck Forms Supported by Tubular Steel
Scaffolding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446
Adjustable Steel Forms for Bridge Decks . . . . . . . . . 447
All-Steel Forms for Bridge Structures . . . . . . . . . . . . 449
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450
17 Flying Deck Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Advantages of Flying Forms . . . . . . . . . . . . . . . . . . . . 451
Form-Eze Flying Deck Forms . . . . . . . . . . . . . . . . . . . 454
Versatility of Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . 456
Patent Construction Systems . . . . . . . . . . . . . . . . . . . 460
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
A Dimensional Tolerances for Concrete
Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465
B Guidelines for Safety Requirements for Shoring
Concrete Formwork . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
C OSHA Regulations for Formwork and Shoring . . . 493
D Conversion of Units of Measure between
U.S. Customary System and Metric System . . . . . . 505
E Directory of Organizations and Companies
Related to Formwork for Concrete . . . . . . . . . . . . . . 507
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513
About Author:
I am Thomas Britto here to share my experiences in the civil engineering field to all my readers.Today many students are struggling to buy books at high prices. So I decided to start a blog and share my experience and knowledge with all my readers.
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