List of Contributors xii
Preface xiii
1 Introduction 1
1.1 The origins of sandwich technology 1
1.2 Principles of sandwich construction 2
1.3 Requirements for sandwich cladding panels 4
1.4 Wall panels 5
1.5 Panels for cold stores 6
1.6 Roof panels 7
1.7 Methods of manufacture 8
1.7.1 Manufacture of facings 8
1.7.2 Panels with bonded cores 8
1.7.3 Foamed cores 9
1.8 Design requirements for structural sandwich panels 10
1.9 Structural design of sandwich panels 11
1.10 Layout of this book 12
2 Materials 14
2.1 Introduction 14
2.2 Facing materials 14
2.2.1 Steel facings 15
2.2.2 Aluminium sheeting 20
2.2.3 Other metal face materials 22
2.2.4 Other facing materials 24
2.3 Core materials 26
2.3.1 Rigid plastic foam materials 28
2.3.2 Characteristic properties of rigid foams 33
2.3.3 Inorganic core material 36
2.3.4 Characteristic properties of mineral wools 38
2.4 Honeycomb cores 39
2.5 Adhesives and other components 40
2.5.1 Mechanical properties 41
2.6 Fasteners and other components 41
2.7 References 41
3 Thermal Performance and Water-Tightness 43
3.1 Introduction 43
3.2 Insulation theory 43
3.2.1 Factors influencing the thermal conductivity of a material 44
3.3 Thermal resistance 46
3.3.1 Total thermal resistance of a building element 47
3.4 Thermal transmittance coefficient (U-value) 47
3.4.1 Calculation method for profiled panels 48
3.5 Thermal capacity 49
3.6 Thermal bridges 50
3.7 Air-tightness 51
3.7.1 Test methods for air-tightness 53
3.8 Water-tightness 53
3.8.1 Test methods for water-tightness 54
3.9 Moisture 55
3.9.1 Surface condensation 57
3.9.2 Moisture transfer 57
3.10 Thermographic surveys 58
3.11 The advantage of sandwich construction in the context of thermal insulation 59
3.12 Energy saving 59
3.13 Reference 61
4 Acoustics 62
4.1 Introduction 62
4.2 What is sound? 62
4.2.1 Decibel arithmetic 64
4.3 Fundamental acoustic parameters 65
4.4 Sound insulation 66
4.4.1 Example 1 67
4.5 Weighted sound reduction index 67
4.6 Overall sound reduction index 68
4.6.1 Example 2 69
4.7 Flanking transmission 69
4.8 Sound reduction index for holes and slits 70
4.9 Sound reduction index for a sandwich panel 71
4.10 Sound in rooms 73
4.10.1 Sound absorption 73
4.10.2 Sound absorption for sandwich panels 74
4.11 Noise reduction in small industrial premises 75
4.11.1 Example 3 76
4.12 Noise reduction in large industrial premises 76
4.12.1 Reverberation time 76
4.12.2 Room classification 77
4.12.3 Sound propagation 78
4.12.4 General sound level reduction 78
4.12.5 Example 4 79
4.13 References 80
5 Fire 81
5.1 General aspects of fire behaviour 81
5.1.1 Introduction 81
5.1.2 Objectives of fire safety design 82
5.1.3 Phases of a fire 83
5.1.4 Assessment of the threat to life 86
5.1.5 Fire severity 88
5.1.6 Introduction to reaction to fire 92
5.1.7 Introduction to fire resistance 94
5.1.8 Fire safety legislation 97
5.1.9 Large-scale fire tests and experience of actual fires 98
5.2 Fire tests 99
5.2.1 Use of standard fire tests 99
5.2.2 Reaction-to-fire tests 99
5.2.3 Fire resistance tests 102
5.3 Material properties at elevated temperature 103
5.3.1 Face materials 103
5.3.2 Core materials 107
5.3.3 Adhesives 111
5.3.4 Mechanical fasteners 111
5.4 Design considerations 112
5.4.1 General 112
5.4.2 Design for fire safety 112
5.4.3 Fire regulations 113
5.4.4 Insurance requirements 114
5.4.5 Structural support for panel assemblies 114
5.4.6 Loading and restraint of the panel assembly 115
5.4.7 Spread of fire within the core 118
5.4.8 Fire stopping 118
5.4.9 Joints in the panel assembly 119
5.4.10 Sealants 120
5.4.11 Fire protection 121
5.4.12 Retention of panel facings 122
5.4.13 Fire load of panels 128
5.4.14 Choice of panel facings 129
5.4.15 Choice of core material 129
5.4.16 Choice of adhesives 130
5.4.17 Required behaviour for horizontal panels (both ceiling and roof panels) 130
5.4.18 Required behaviour for vertical panels (internal and external walls) 131
5.5 Engineering solutions 131
5.5.1 External walls 132
5.5.2 Internal walls 137
5.5.3 Roofs 138
5.5.4 Ceilings 139
5.6 Reparability after fire 141
5.7 Check list for designers 141
5.8 References 144
5.8.1 Additional references for wider reading 146
6 Durability 148
6.1 General aspects of durability 148
6.2 Prediction of the lifetime of a structure 150
6.3 Actions on sandwich panels which may cause degradation 151
6.3.1 Actions causing mechanical degradation 152
6.3.2 Actions causing physical degradation 152
6.4 Accelerated test methods 153
6.4.1 Durability of the panel 153
6.4.2 Effect of temperature variations and moisture on strength properties 157
6.4.3 Tests for durability 158
6.4.4 Durability of the adhesive 161
6.4.5 Durability of facing materials 164
6.5 Guidelines for the choice of materials and fasteners 166
6.5.1 Core material 166
6.5.2 Adhesives 166
6.5.3 Face material 166
6.5.4 Fasteners 167
6.6 References 167
7 Refrigerated Warehouses, Cold Stores and Chill Rooms 168
7.1 Introduction 168
7.1.1 Cold stores and chill rooms inside the building 170
7.2 Thermal insulation 171
7.3 Air-tightness 171
7.4 Moisture barriers 172
7.5 Fire 173
7.6 Details 173
7.7 Special considerations applying to sandwich panel outer walls 175
7.7.1 Allowing for reactions to mechanical and thermal loads 175
7.7.2 Thermal expansion/contraction and panel deformation 177
7.8 The engineering design of sandwich panels 177
7.8.1 Using panel supports having lateral degrees of freedom 178
7.8.2 Pre-flexed panel outer faces 180
7.9 Structural features requiring special attention 182
8 Special Architectural Applications 184
8.1 Introduction 184
8.2 Cladding details 184
8.3 Industrial and commercial buildings 184
8.3.1 Esso UK plc corporate headquarters, Leatherhead, UK 185
8.3.2 Manufacturing facility for Compaq Computer Corporation, Erskine, Scotland 185
8.4 High-technology architectural wall panels 185
8.4.1 Case Study: Aspect Mark II 187
8.5 References 191
9 Principles of Structural Behaviour 193
9.1 Introduction 193
9.1.1 Types of panels 194
9.2 Analysis of panels with flat or lightly profiled faces 195
9.2.1 Case 1: Simply supported panel with a uniformly distributed load 197
9.2.2 Case 2: Simply supported panel with a point load 199
9.2.3 Case 3: Simply supported panel with a temperature difference 200
9.2.4 Solutions for two- and three-span panels 201
9.2.5 More general cases of loading and support conditions 202
9.3 Analysis of panels with profiled faces 204
9.3.1 Simply supported panel with a uniformly distributed load of q per unit length 206
9.3.2 Simply supported panel with a point load anywhere in the span 208
9.3.3 Simply supported panel with a temperature difference between the faces 209
9.3.4 Solutions for two- and three-span panels 210
9.4 Approximate solutions for some simple cases 210
9.5 Finite-element and other numerical methods 217
9.5.1 Force-deformation relationships219
9.6 Axially loaded sandwich panels 223
9.7 Sandwich panels spanning in two directions (sandwich plates) 223
9.7.1 Simply supported panel with flat or quasi-flat faces 224
9.8 References 225
10 Load-bearing Capacity 227
10.1 Principles of the evaluation of resistance 227
10.2 Failure modes 229
10.2.1 Tensile and compressive failure of the faces 230
10.2.2 Failure of the core and face at the support with positive support reaction 237
10.2.3 Failure of the core and face at a support subject to negative support reaction 248
10.2.4 Shear failure of the core 252
10.2.5 Shear failure of a profiled face 254
10.2.6 Connections 254
10.2.7 Deflections 256
10.3 Derivation of the theoretical expressions for buckling stress 258
10.4 Derivation of expressions for the interaction at intermediate supports 262
10.5 Conclusions 266
10.6 References 267
11 Loads, Load and Material Factors and Design Procedure 269
11.1 Design equation 269
11.2 Loads on sandwich panels 271
11.3 Choice of the method of analysis 273
11.4 Safety factors 274
11.5 Load combinations 276
11.6 Permissible short-term and long-term deflections 280
11.7 Conclusions 281
11.8 References 282
12 Additional Structural Considerations 284
12.1 Introduction 284
12.2 Details of sandwich structures 284
12.2.1 Details for external walls 285
12.2.2 Details for external roofs 285
12.2.3 Details for internal walls 286
12.2.4 Details for ceilings 288
12.3 Connections between a sandwich panel and the supporting structure 288
12.4 Effect of openings 293
12.5 Flexibility of fasteners and supports 298
12.6 Lateral and rotational stiffness of fastenings 304
12.7 Capacity under axial load 307
12.8 Diaphragm action 311
12.9 Conclusions 313
12.10 References 313
13 Mechanical Testing 315
13.1 Introduction 315
13.2 Tests on core materials 316
13.3 Tests to determine the wrinkling stress 323
13.4 Tests to determine the interactions between bending moment and support force 324
13.5 Creep and long-term strength tests 325
13.6 Tests on fasteners 325
13.7 Tests used in quality control 325
13.8 Statistical interpretation of test data 327
13.9 Detailed test procedures 327
13.9.1 General 327
13.9.2 Test environment and conditioning of test specimens 328
13.9.3 Test procedures for material properties 328
13.9.4 Tests on complete panels 334
13.9.5 Tests on fasteners and connections 342
13.10 References 345
14 Examples of Calculation Procedures 346
14.1 General 346
14.2 Two-span wall panel 346
14.2.1 Actions (loads) 347
14.2.2 Cross-section of the panel 347
14.2.3 Design values for the panel 348
14.2.4 Load, material and combination factors 348
14.2.5 Ultimate limit state 348
14.2.6 Serviceability limit state 350
14.2.7 Comments on the calculations 356
14.3 Two-span roof panel 357
14.3.1 Actions (loads) 357
14.3.2 Cross-section of the panel 358
14.3.3 Design values for the panel 358
14.3.4 Load, material and combination factors 359
14.3.5 Calculation of the initial design parameters 359
14.3.6 Ultimate limit state 359
14.3.7 Serviceability limit state 363
14.3.8 Design of fasteners 367
14.3.9 Comments on the calculations 367
14.4 Reference 367
Index 369
