The Fabric Formwork Book

Methods for Building New Architectural and Structural Forms in Concrete

Mark West

I~ ~~o~;~~~~;up LONDON AND NEW YORK

Contents

ACKNOWLEDGEMENTS IX PART 2 CONSTRUCTION 48

THEAUTHOR XI INTRODUCTION 49 How the content is organized 49

CONTRIBUTING AUTHORS XII Flat-sheet moulds 49

PHOTO AND ILLUSTRATION CREDITS XIV Models 49 Subtly different skills 49

INTRODUCTION XIX How to use this book XX

CHAPTER 4 TEXTILES 51

PART 1 ABOUT FLEXIBLE FORMWORKS 1 The basics 52 General considerations 52

CHAPTER 1 ON FLEXIBILITY 3 Material behavior (mechanical properties) 52

Control 4 Textile structure 53 53 Woven textiles New language of form 11

Deformation "on the bias" 53 Knit textiles 54

CHAPTER 2 THE HISTORY OF 17 Non-wovens 54 FABRIC FORMWORK Plastic films 54

Diederik Veenendaal Coated and uncoated textiles 54 Preferred formwork fabric types 54

The inventions of the fabric-formed floor 18 (woven polyethylene (PE) and polypropylene

The wider potential of fabric formwork 20 (PP) fabrics)

The Ctesiphon system and its legacy 22 On the robustness of flexible moulds 55

Shell structures and the cost of formwork 24 Polyethylene (PE) vs. polypropylene (PP) 56

Architectural expression 28 Coated vs. uncoated PP and PE textiles 56

Marine and geotechnical applications 30 Uncoated (permeable) PP and PE fabrics - 56

of fabric formworks filtering fabric mould-walls

Contemporary fabric-formed architecture 33 Coated PE or PP textiles 59

Conclusions 34 Differences in handling coated or 60 uncoated fabrics

CHAPTER 3 STRUCTURAL INTELLIGENCE 39 Finally 60 IN FLEXIBLE MATERIALS Fabric handling 60

Edward Allen, John Ochsendorf, and Mark West Slack-sheet moulds 61 Creases 61

Funicular forms 40 Thermo-forming 61 Flow of forces in solids 41 Push-buckles 61 Following curved force flows in fabric-formed 44 Energized (tensioned) formwork sheets 61 structures Stress and stress distribution 61

Pressurized membranes - a co-incidence 45 Pre-tensioning 62 of skins Pull-buckles 63

Box: Materials Savings in Flexible Fabric Moulds 46 Pull-buckles and pre-tensioning from impactos 63 Sewing 64

Sewing PP or PE fabrics 64 Sewing stretch-knit fabrics 64 Cutting, marking, and drawing on fabrics 64 Handling fabric at joints and connections 64

vi Fabric Formwork

CHAPTER 5 CONCRETE 65 Pressed edges 108 Foam rubber edge-frame 109

Concrete's constituent parts - mix designs 66 Cut fabric edges 109 General considerations 66 Matched jaws 109 Admixtures 67 Scaffolding strategies 110 Water-cement ratio 67 Strong-backs 111 Concrete shrinkage 67 Spaced tables 112 Concrete slump and plasticity 67 "Loose" supports 113 Self-compacting concrete (SCC) 67 Reinforcing 115 Vibration/compaction 67 Rebar connections 115 Fiber reinforced concrete (FRC) 67 Special considerations: rebar tie-wire 117 Ultra high performance concrete (UHPC) 68 Special considerations when placing 68

concrete in flexible moulds CHAPTER 7 TIPS & TRICKS 119

Aggregate size and shape 68 Watertests 120

Sequential lifts 68 Weiding burns 122

Pour rate 68 Drawing on plastic fabrics 122

Special considerations with permeable 68 Captured fabric 122

fabric moulds Undercut or "keyed" rigidified fabric moulds 124

Finally 68 Cutting, and finishing plastic rope 125 Cutting plastic fabrics 126

CHAPTER 6 CONNECTIONS 70 Heat-setting thermoplastic sheets 127

Marl< West and Ronnie Araya Air bubbles (bug holes) 128 Fitting rigid frames to fabric-formed 129

General considerations 71 concrete surfaces Stress distribution 71 Rope tricks for mechanical advantage 130

Fabric-to-fabric connections 72 in pre-tensioning Fabric-to-fabric "jointless" connections 73 Complex surface geometry made simple 134 Fabric-to-fabric heat-welding 74 On shaping impactos 134 Fabric-to-fabric sewing 74 A note on tape 134 Fabric-to-fabric spline connections 77 Flexible mould edges 134 Fabric-to-fabric lacing and laced splines 78 External vibration 134 Rolled-and-tied closures 83 A note on filling permeable moulds 135 Fabric-to-fabric plastic "zip-ties" 84 On filling coated-fabric moulds 135 Fabric-to-fabric pinning 84 External manipulations of a pressurized 135 Fabric-to-fabric clamping 85 mould

Fabric-to-frame connections 86 Fragility of recently set concrete in flexible Fabric-to-frame clamp or pressure plates 86 moulds 135 Fabric-to-frame stapling 88 On the robustness of flexible moulds: 135 Fabric-to-frame clamping 90 repair during casting Fabric-to-frame screwing/pinning 90

Other connections 92

Free pull-points 93 CHAPTER 8 CAST-IN-PLAGE COLUMN 136

lmpactos 94 MOULDS

Wrapped ball 96 Box: Pressure and Fabric-Tension in a Column 137

Pre-stress with a threaded rod 96 Mould

Stencil frames 97 Commercially available column moulds 138

Form-ties 98 Custom-made column moulds 140

Voids and openings (block-outs) 100 Multiple strong-back moulds 142

"Jointless" edge connections 102 Asymmetry in tension membrane moulds 143

Binding ties 105 Bulge-wall columns 145

Sequential casts 105 Liner + jacket methods 146

Other sequential pours 107 Stretch-knit fabrics in column moulds 150

Edge-frame connections against curved 108 Vertical pre-tensioning 150

fabric sheets

Contents vii

Column capitals 152 Column-to-beam branching shapes 258 A note on column reinforcing 155 Excess fabric at branching joints 260

Horizontal, branching, open trough moulds 263

CHAPTER 9 CAST-IN-PLAGE WALL MOULDS 156 Pre-tensioned branching shapes 273 Truss moulds 27 4

"Quilt-point" method 157 Summation: Construction With Fabric 281

Frame-restraint method 162 Formworks

Zero-waste wall formwork 164 Advantages of fabric formworks 281

Bulge-wall method 166 Advantages of flat-sheet formworks 281 Disadvantages of fabric formworks 281 Disadvantages of flat-sheet formworks 281

CHAPTER 10 OPEN TROUGH MOULDS 169 CODA 282

Foundation formworks 170 REFERENCES 283 "Fast-Foot" 170 Strip footings and step footings 171 PATENTS 287

Variable-section open trough moulds 172 GLOSSARY 289 Variable-section pre-cast columns 173 Other variable-section moulds 17 4 INDEX 296 Elastica curves 178 Open trough moulds for tilt-up walls 181 and facades

Open trough moulds for variable-section 184 beams

Longitudinal pre-tensioning 189 Variable-section open trough moulds - 190

keel method

CHAPTER 11 NON-PRESSURIZED MOULDS 193 Mark West and Ronnie Araya

Open pan fabric formworks 194 Drumhead open pan formworks 195 Direct casts and inverted casts 196

Box: Vibrating Concrete in Permeable, Open Pan Moulds 198

Slack-sheet open pan moulds 199 Wrinkled sheets 205 Spray-foam-backed moulds 211 Rigidified fabric moulds 212

Hanging sheet moulds 220 Horizontal hanging sheet moulds 220 Vertical hanging curtain moulds 228

Box: Funicular Vaults and Thin-Shells; Double Curvature in Shells 236

lnverted hanging sheet moulds and 237 structural shells

Direct-cast thin-shell vaults 246

CHAPTER 12 250 TRUSS AND BRANCHING FORMS

Naturally formed branching shapes 251 Stencil frames as guides for branching 252 shapes

viii Fabric Formwork