Aluminium Design and Construction

310 Pages·1998·4.843 MB·\310

by  John Dwight (Author)

Aluminium Design and

Construction

Aluminium Design and

Construction

John Dwight
MSc, FI Struct E

Former Reader in Structural Engineering,

University of Cambridge; and Fellow of Magdalene College, Cambridge

E & FN SPON

An Imprint of Routledge

London and New York
First published 1999
by E & FN Spon, an imprint of Routledge
11 New Fetter Lane, London EC4P 4EE
This edition published in the Taylor & Francis e-Library, 2002.
Simultaneously published in the USA and Canada
by Routledge
29 West 35th Street, New York, NY 10001
© 1999 John Dwight
All rights reserved. No part of this book may be reprinted or reproduced or
utilized in any form or by any electronic, mechanical, or other means, now
known or hereafter invented, including photocopying and recording, or in any
information storage or retrieval system, without permission in writing from the
publishers.
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging in Publication Data
Dwight, J.B. (John B.), 1921–
Aluminium design and construction/J.B.Dwight.
p. cm.
Includes bibliographical references and index.
ISBN 0-419-15710-7 (Print Edition)
1. Aluminum construction. 2. Aluminum. 3. Aluminum, Structural.
4. Structural design—Standards—Europe. I. Title
TA690.D855 1998
624.1'826–dc21 98–39235
CIP
ISBN 0 419 15710 7 (Print Edition)
ISBN 0-203-02819-8 Master e-book ISBN
ISBN 0-203-13449-4 (Glassbook Format)
Contents

Preface ...................................................................................................... xiv

Acknowledgements .................................................................................. xv

List of symbols and conversion factors .............................................. xvi

1 About aluminium ............................................................................... 1

1.1 General description ................................................................. 1

1.1.1 The element ................................................................. 1

1.1.2 The name ...................................................................... 1

1.1.3 The industrial metal .................................................. 2

1.1.4 Alloys ............................................................................ 2

1.1.5 Castings......................................................................... 2

1.1.6 Supposed health risk ................................................. 2

1.1.7 Supposed fire risk ...................................................... 3

1.2 Physical properties .................................................................. 3

1.3 Comparison with steel ........................................................... 5

1.3.1 The good points about aluminium ........................ 6

1.3.2 The bad points ............................................................ 6

1.4 History ........................................................................................ 8

1.4.1 The precious metal stage .......................................... 8

1.4.2 The big breakthrough ................................................ 9

1.4.3 Early applications ....................................................... 9

1.4.4 Establishment of the alloys ...................................... 10

1.4.5 The first major market .............................................. 10

1.5 Aluminium since 1945 ............................................................ 11

1.5.1 Growth in output ....................................................... 11

1.5.2 New technology .......................................................... 12

1.5.3 Structural engineering ............................................... 13

1.5.4 Architecture.................................................................. 14

1.5.5 Land transport ............................................................ 14

1.5.6 Marine usage ............................................................... 15

1.6 Sources of information ........................................................... 16

2 Manufacture ........................................................................................ 23

2.1 Production of aluminium metal ........................................... 23

2.1.1 Primary production .................................................... 23

2.1.2 Secondary metal ......................................................... 24

2.2 Flat products ............................................................................. 24
vi Contents
2.2.1 Rolling mill practice .................................................. 24

2.2.2 Plate ............................................................................... 25

2.2.3 Sheet .............................................................................. 25

2.2.4 Tolerance on thickness .............................................. 25

2.2.5 Special forms of flat product................................... 26

2.3 Extruded sections .................................................................... 27

2.3.1 Extrusion process ........................................................ 27

2.3.2 Heat-treatment of extrusions ................................... 28

2.3.3 Correction ..................................................................... 29

2.3.4 Dies ................................................................................ 29

2.3.5 Hollow sections ........................................................... 31

2.3.6 Extrudability of different alloys .............................. 33

2.3.7 Size and thickness limits .......................................... 34

2.3.8 Tolerances ..................................................................... 35

2.3.9 Design possibilities with extrusions ...................... 36

2.4 Tubes ........................................................................................... 38

2.4.1 Extruded tube .............................................................. 38

2.4.2 Drawn tube .................................................................. 38

2.4.3 Welded tube ................................................................. 39

3 Fabrication ............................................................................................ 40

3.1 Preparation of material .......................................................... 40

3.1.1 Storage .......................................................................... 40

3.1.2 Cutting .......................................................................... 40

3.1.3 Holing............................................................................ 40

3.1.4 Forming ......................................................................... 41

3.1.5 Machining ..................................................................... 42

3.2 Mechanical joints ..................................................................... 42

3.2.1 Bolting and screwing ................................................. 42

3.2.2 Friction-grip bolting ................................................... 44

3.2.3 Riveting ......................................................................... 44

3.3 Arc welding .............................................................................. 46

3.3.1 Use of arc welding ..................................................... 46

3.3.2 MIG welding ............................................................... 46

3.3.3 TIG welding ................................................................. 47

3.3.4 Filler metal ................................................................... 48

3.3.5 Weld inspection........................................................... 49

3.4 Friction-stir welding ................................................................ 50

3.4.1 The process .................................................................. 50

3.4.2 Features of FS welding ............................................. 52

3.4.3 Limitations ................................................................... 52

3.4.4 Applications ................................................................. 53

3.5 Other welding processes ........................................................ 53

3.6 Adhesive bonding ................................................................... 53

3.6.1 Use of bonding ........................................................... 53
Contents vii

3.6.2 Surface preparation .................................................... 54

3.6.3 Two-component adhesives ....................................... 55

3.6.4 One-component adhesives ........................................ 55

3.6.5 Applying the adhesive .............................................. 55

3.6.6 Clamping ...................................................................... 56

3.6.7 Curing ........................................................................... 56

3.7 Protection and finishing ......................................................... 56

3.7.1 General description .................................................... 56

3.7.2 Pretreatment ................................................................. 57

3.7.3 Anodizing ..................................................................... 57

3.7.4 Painting ......................................................................... 58

3.7.5 Contact with other materials ................................... 58

4 Aluminium alloys and their properties ........................................ 59

4.1 Numbering system for wrought alloys .............................. 59

4.1.1 Basic system ................................................................. 59

4.1.2 Standardization of alloys .......................................... 59

4.1.3 Work hardening .......................................................... 60

4.1.4 The O and F conditions ............................................ 61

4.1.5 Relation between temper and tensile strength.... 62

4.1.6 Availability of different tempers ............................ 63

4.1.7 Heat-treated material ................................................. 63

4.2 Characteristics of the different alloy types ....................... 64

4.2.1 Non-heat-treatable alloys .......................................... 65

4.2.2 Heat-treatable alloys .................................................. 67

4.3 Data on selected wrought alloys ......................................... 68

4.3.1 How mechanical properties are specified ............ 68

4.3.2 Specific alloys and their properties ....................... 69

4.3.3 Comments on certain alloys .................................... 70

4.3.4 Minimum bend radius .............................................. 74

4.3.5 Strength variation with temperature ..................... 75

4.3.6 Properties of forgings ................................................ 76

4.4 Stress-strain curves .................................................................. 78

4.4.1 Empirical stress-strain relation ................................ 78

4.4.2 Stress-strain curve for minimum strength material 79

4.5 Casting alloys ........................................................................... 80

4.5.1 Numbering system ..................................................... 80

4.5.2 Three useful casting alloys ...................................... 81

4.6 Alloys used in joints ............................................................... 82

4.6.1 Fastener materials ...................................................... 82

4.6.2 Weld filler wire ........................................................... 82

4.7 Corrosion ................................................................................... 82

4.7.1 Corrosion of exposed surfaces ................................ 82

4.7.2 When to protect against corrosion ......................... 84

4.7.3 Bimetallic corrosion.................................................... 85
viii Contents
5 Limit state design and limiting stresses ....................................... 87

5.1 Limit state design .................................................................... 87

5.1.1 General description .................................................... 87

5.1.2 Definitions .................................................................... 87

5.1.3 Limit state of static strength .................................... 89

5.1.4 Serviceability limit state ........................................... 92

5.1.5 Limit state of fatigue ................................................. 93

5.2 The use of limiting stresses .................................................. 94

5.3 Limiting stresses based on material properties................ 94

5.3.1 Derivation ..................................................................... 94

5.3.2 Procedure in absence of specified properties ...... 96

5.3.3 Listed values ................................................................ 97

5.4 Limiting stresses based on buckling ................................... 98

5.4.1 General form of buckling curves............................ 98

5.4.2 Construction of the design curves ......................... 99

5.4.3 The design curves ...................................................... 100

6 Heat-affected zone softening at welds .......................................... 102

6.1 General description ................................................................. 102

6.2 Thermal control ........................................................................ 103

6.3 Patterns of softening ............................................................... 104

6.3.1 Heat-treated material ................................................. 104

6.3.2 Work-hardened material ........................................... 105

6.3.3 Stress-strain curve of HAZ material ...................... 106

6.3.4 Multi-pass welds ........................................................ 107

6.3.5 Recovery time .............................................................. 107

6.4 Severity of HAZ softening .................................................... 108

6.4.1 Softening factor ........................................................... 108

6.4.2 Heat-treated material ................................................. 108

6.4.3 Work-hardened material ........................................... 109

6.5 Extent of the softened zone .................................................. 109

6.5.1 General considerations .............................................. 109

6.5.2 Nominal HAZ ............................................................. 111

6.5.3 One-inch rule ............................................................... 111

6.5.4 RD method ................................................................... 112

6.5.5 Weld geometry ............................................................ 112

6.5.6 Single straight MIG weld ......................................... 114

6.5.7 Variation of HAZ extent with weld size .............. 116

6.5.8 Overlapping HAZs..................................................... 117

6.5.9 Attachment welds ...................................................... 118

6.5.10 Definition of an isolated weld (10A-rule) ............ 119

6.5.11 RD method, summary ............................................... 120

6.6 Application of HAZ data to design .................................... 120

6.6.1 Design of members .................................................... 120

6.6.2 Design of joints ........................................................... 121
Contents ix
6.7 Comparison with one-inch rule ........................................... 122

6.8 HAZ at TIG welds .................................................................. 123

6.8.1 Difference between TIG and MIG welding ......... 123

6.8.2 Severity of softening with TIG welding ............... 124

6.8.3 Extent of softened zone for TIG welding............. 125

6.9 HAZ at friction-stir welds ..................................................... 125

7 Plate elements in compression ........................................................ 126

7.1 General description ................................................................. 126

7.1.1 Local buckling ............................................................. 126

7.1.2 Types of plate element .............................................. 126

7.1.3 Plate slenderness parameter .................................... 127

7.1.4 Element classification (compact or slender) ........ 127

7.1.5 Treatment of slender elements ................................ 128

7.2 Plain flat elements in uniform compression ..................... 128

7.2.1 Local buckling behaviour ......................................... 128

7.2.2 Limiting values of plate slenderness ..................... 130

7.2.3 Slender internal elements ......................................... 130

7.2.4 Slender outstands ....................................................... 131

7.2.5 Very slender outstands .............................................. 134

7.3 Plain flat elements under strain gradient .......................... 135

7.3.1 Internal elements under strain gradient, general

description .................................................................... 135

7.3.2 Internal elements under strain gradient, classification 136

7.3.3 Slender internal elements under strain gradient .. 138

7.3.4 Outstands under strain gradient, general description 139

7.3.5 Outstands under strain gradient, case T .............. 140

7.3.6 Outstands under strain gradient, case R .............. 140

7.4 Reinforced elements ................................................................ 141

7.4.1 General description .................................................... 141

7.4.2 Limitations on stiffener geometry .......................... 142

7.4.3 ‘Standard’ reinforcement .......................................... 143

7.4.4 Location of the stiffener............................................ 143

7.4.5 Modified slenderness parameter ............................ 144

7.4.6 Classification ................................................................ 145

7.4.7 Slender reinforced elements ..................................... 146

8 Beams .................................................................................................... 148

8.1 General approach..................................................................... 148

8.2 Moment resistance of the cross-section .............................. 149

8.2.1 Moment-curvature relation ...................................... 149

8.2.2 Section classification .................................................. 150

8.2.3 Uniaxial moment, basic formulae .......................... 150

8.2.4 Effective section .......................................................... 151

8.2.5 Hybrid sections ........................................................... 152