Aluminium Design and Construction Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 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 Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 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) Copyright 1999 by Taylor & Francis Group. All Rights Reserved. Contents Preface Acknowledgements List of symbols and conversion factors 1 About aluminium 1.1 General description 1.1.1 The element 1.1.2 The name 1.1.3 The industrial metal 1.1.4 Alloys 1.1.5 Castings 1.1.6 Supposed health risk 1.1.7 Supposed fire risk 1.2 Physical properties 1.3 Comparison with steel 1.3.1 The good points about aluminium 1.3.2 The bad points 1.4 History 1.4.1 The precious metal stage 1.4.2 The big breakthrough 1.4.3 Early applications 1.4.4 Establishment of the alloys 1.4.5 The first major market 1.5 Aluminium since 1945 1.5.1 Growth in output 1.5.2 New technology 1.5.3 Structural engineering 1.5.4 Architecture 1.5.5 Land transport 1.5.6 Marine usage 1.6 Sources of information 2 Manufacture 2.1 Production of aluminium metal 2.1.1 Primary production 2.1.2 Secondary metal 2.2 Flat products Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 2.2.1 Rolling mill practice 2.2.2 Plate 2.2.3 Sheet 2.2.4 Tolerance on thickness 2.2.5 Special forms of flat product 2.3 Extruded sections 2.3.1 Extrusion process 2.3.2 Heat-treatment of extrusions 2.3.3 Correction 2.3.4 Dies 2.3.5 Hollow sections 2.3.6 Extrudability of different alloys 2.3.7 Size and thickness limits 2.3.8 Tolerances 2.3.9 Design possibilities with extrusions 2.4 Tubes 2.4.1 Extruded tube 2.4.2 Drawn tube 2.4.3 Welded tube 3 Fabrication 3.1 Preparation of material 3.1.1 Storage 3.1.2 Cutting 3.1.3 Holing 3.1.4 Forming 3.1.5 Machining 3.2 Mechanical joints 3.2.1 Bolting and screwing 3.2.2 Friction-grip bolting 3.2.3 Riveting 3.3 Arc welding 3.3.1 Use of arc welding 3.3.2 MIG welding 3.3.3 TIG welding 3.3.4 Filler metal 3.3.5 Weld inspection 3.4 Friction-stir welding 3.4.1 The process 3.4.2 Features of FS welding 3.4.3 Limitations 3.4.4 Applications 3.5 Other welding processes 3.6 Adhesive bonding 3.6.1 Use of bonding Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 3.6.2 Surface preparation 3.6.3 Two-component adhesives 3.6.4 One-component adhesives 3.6.5 Applying the adhesive 3.6.6 Clamping 3.6.7 Curing 3.7 Protection and finishing 3.7.1 General description 3.7.2 Pretreatment 3.7.3 Anodizing 3.7.4 Painting 3.7.5 Contact with other materials 4 Aluminium alloys and their properties 4.1 Numbering system for wrought alloys 4.1.1 Basic system 4.1.2 Standardization of alloys 4.1.3 Work hardening 4.1.4 The O and F conditions 4.1.5 Relation between temper and tensile strength 4.1.6 Availability of different tempers 4.1.7 Heat-treated material 4.2 Characteristics of the different alloy types 4.2.1 Non-heat-treatable alloys 4.2.2 Heat-treatable alloys 4.3 Data on selected wrought alloys 4.3.1 How mechanical properties are specified 4.3.2 Specific alloys and their properties 4.3.3 Comments on certain alloys 4.3.4 Minimum bend radius 4.3.5 Strength variation with temperature 4.3.6 Properties of forgings 4.4 Stress-strain curves 4.4.1 Empirical stress-strain relation 4.4.2 Stress-strain curve for minimum strength material 4.5 Casting alloys 4.5.1 Numbering system 4.5.2 Three useful casting alloys 4.6 Alloys used in joints 4.6.1 Fastener materials 4.6.2 Weld filler wire 4.7 Corrosion 4.7.1 Corrosion of exposed surfaces 4.7.2 When to protect against corrosion 4.7.3 Bimetallic corrosion Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 5 Limit state design and limiting stresses 5.1 Limit state design 5.1.1 General description 5.1.2 Definitions 5.1.3 Limit state of static strength 5.1.4 Serviceability limit state 5.1.5 Limit state of fatigue 5.2 The use of limiting stresses 5.3 Limiting stresses based on material properties 5.3.1 Derivation 5.3.2 Procedure in absence of specified properties 5.3.3 Listed values 5.4 Limiting stresses based on buckling 5.4.1 General form of buckling curves 5.4.2 Construction of the design curves 5.4.3 The design curves 6 Heat-affected zone softening at welds 6.1 General description 6.2 Thermal control 6.3 Patterns of softening 6.3.1 Heat-treated material 6.3.2 Work-hardened material 6.3.3 Stress-strain curve of HAZ material 6.3.4 Multi-pass welds 6.3.5 Recovery time 6.4 Severity of HAZ softening 6.4.1 Softening factor 6.4.2 Heat-treated material 6.4.3 Work-hardened material 6.5 Extent of the softened zone 6.5.1 General considerations 6.5.2 Nominal HAZ 6.5.3 One-inch rule 6.5.4 RD method 6.5.5 Weld geometry 6.5.6 Single straight MIG weld 6.5.7 Variation of HAZ extent with weld size 6.5.8 Overlapping HAZs 6.5.9 Attachment welds 6.5.10 Definition of an isolated weld (10A-rule) 6.5.11 RD method, summary 6.6 Application of HAZ data to design 6.6.1 Design of members 6.6.2 Design of joints Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 6.7 Comparison with one-inch rule 6.8 HAZ at TIG welds 6.8.1 Difference between TIG and MIG welding 6.8.2 Severity of softening with TIG welding 6.8.3 Extent of softened zone for TIG welding 6.9 HAZ at friction-stir welds 7 Plate elements in compression 7.1 General description 7.1.1 Local buckling 7.1.2 Types of plate element 7.1.3 Plate slenderness parameter 7.1.4 Element classification (compact or slender) 7.1.5 Treatment of slender elements 7.2 Plain flat elements in uniform compression 7.2.1 Local buckling behaviour 7.2.2 Limiting values of plate slenderness 7.2.3 Slender internal elements 7.2.4 Slender outstands 7.2.5 Very slender outstands 7.3 Plain flat elements under strain gradient 7.3.1 Internal elements under strain gradient, general description 7.3.2 Internal elements under strain gradient, classification 7.3.3 Slender internal elements under strain gradient 7.3.4 Outstands under strain gradient, general description 7.3.5 Outstands under strain gradient, case T 7.3.6 Outstands under strain gradient, case R 7.4 Reinforced elements 7.4.1 General description 7.4.2 Limitations on stiffener geometry 7.4.3 ‘Standard’ reinforcement 7.4.4 Location of the stiffener 7.4.5 Modified slenderness parameter 7.4.6 Classification 7.4.7 Slender reinforced elements 8 Beams 8.1 General approach 8.2 Moment resistance of the cross-section 8.2.1 Moment-curvature relation 8.2.2 Section classification 8.2.3 Uniaxial moment, basic formulae 8.2.4 Effective section 8.2.5 Hybrid sections Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 8.2.6 Use of interpolation for semi-compact sections 8.2.7 Semi-compact section with tongue plates 8.2.8 Local buckling in an under-stressed compression flange 8.2.9 Biaxial moment 8.3 Shear force resistance 8.3.1 Necessary checks 8.3.2 Shear yielding of webs, method 1 8.3.3 Shear yielding of webs, method 2 8.3.4 Shear resistance of bars and outstands 8.3.5 Web buckling, simple method, 8.3.6 Web buckling, tension-field action 8.3.7 Inclined webs 8.4 Combined moment and shear 8.4.1 Low shear 8.4.2 High shear, method A 8.4.3 High shear, method B 8.5 Web crushing 8.5.1 Webs with bearing stiffeners 8.5.2 Crushing of unstiffened webs 8.6 Web reinforcement 8.6.1 Types of reinforcement 8.6.2 Tongue plates 8.6.3 Transverse stiffeners 8.6.4 End-posts 8.7 Lateral-torsional buckling 8.7.1 General description 8.7.2 Basic check 8.7.3 Equivalent uniform moment 8.7.4 Limiting stress for LT buckling 8.7.5 Slenderness parameter 8.7.6 Beams with very slender compression flanges 8.7.7 Effective length for LT buckling 8.7.8 Beams of varying cross-section 8.7.9 Effect of simultaneous side moment 8.8 Beam deflection 8.8.1 Basic calculation 8.8.2 Beam of slender section 9 Tension and compression members 9.1 General approach 9.1.1 Modes of failure 9.1.2 Classification of the cross-section (compression members) 9.2 Effective section Copyright 1999 by Taylor & Francis Group. All Rights Reserved. 9.2.1 General idea 9.2.2 Allowance for HAZ softening 9.2.3 Allowance for local buckling 9.2.4 Allowance for holes 9.3 Localized failure of the cross-section 9.4 General yielding along the length 9.5 Column buckling 9.5.1 Basic calculation 9.5.2 Column buckling stress 9.5.3 Column buckling slenderness 9.5.4 Column buckling of struts containing very slender outstands 9.6 Torsional buckling 9.6.1 General description 9.6.2 Interaction with flexure 9.6.3 ‘Type-R’ sections 9.6.4 Sections exempt from torsional buckling 9.6.5 Basic calculation 9.6.6 Torsional buckling stress 9.6.7 Torsional buckling slenderness 9.6.8 Interaction factor 9.6.9 Torsional buckling of struts containing very slender outstands 9.6.10 Empirical slenderness formulae 9.6.11 Torsional buckling of certain standardized sections 9.7 Combined axial force and moment 9.7.1 The problem 9.7.2 Secondary bending in trusses 9.7.3 Section classification 9.7.4 Interaction formulae (P+uniaxial M) 9.7.5 Alternative treatment (P+uniaxial M) 9.7.6 Interaction formulae (P+biaxial M) 9.7.7 Alternative treatment (P+biaxial M) 9.7.8 Treatment of local buckling 9.7.9 Eccentrically connected angles, channels and tees 10 Calculation of section properties 10.1 Summary of section properties used 10.2 Plastic section modulus 10.2.1 Symmetrical bending 10.2.2 Unsymmetrical bending 10.2.3 Bending with axial force 10.2.4 Plastic modulus of the effective section 10.3 Elastic flexural properties 10.3.1 Inertia of a section having an axis of symmetry Copyright 1999 by Taylor & Francis Group. All Rights Reserved. [...]... procedure 11 .1. 3 Joints in shear, fastener force arising 11 .1. 4 Joints in shear, fastener resistance 11 .1. 5 Joints in shear, member failure 11 .1. 6 Joints in tension, fastener force arising 11 .1. 7 Joints in tension, fastener resistance 11 .1. 8 Interaction of shear and tension 11 .1. 9 Comparisons 11 .1. 10 Joints made with proprietary fasteners 11 .2 Mechanical joints (friction-grip) 11 .2 .1 General description 11 .2.2... fusion-boundary failure 11 .3.6 Welded joints carrying axial moment 11 .3.7 Welds under combined loading 11 .3.8 Friction-stir welds 11 .4 Bonded joints 11 .4 .1 General description 11 .4.2 Specification of the adhesive 11 .4.3 Surface preparation 11 .4.4 Effect of moisture 11 .4.5 Factors affecting choice of adhesive 11 .4.6 Creep 11 .4.7 Peeling 11 .4.8 Mechanical testing of adhesives 11 .4.9 Glue-line thickness 11 .4 .10 ... factor 10 .5 Warping calculations 10 .5 .1 Coverage 10 .5.2 Numbering the elements 10 .5.3 Evaluation of warping 10 .5.4 Formula for the warping factor 10 .5.5 Bisymmetric and radial-symmetric sections 10 .5.6 Skew-symmetric sections 10 .5.7 Monosymmetric sections, type 1 10.5.8 Monosymmetric sections, type 2 10 .5.9 Asymmetric sections 11 Joints 11 .1 Mechanical joints (non-torqued) 11 .1. 1 Types of fastener 11 .1. 2... material 11 .2.3 Ultimate limit state (shear loading) 11 .2.4 Serviceability limit state (shear loading) 11 .2.5 Bolt tension and reaction force 11 .2.6 Slip factor 11 .2.7 Serviceability factor 11 .3 Welded joints 11 .3 .1 General description 11 .3.2 Basic checking procedure Copyright 19 99 by Taylor & Francis Group All Rights Reserved 11 .3.3 Weld force arising 11 .3.4 Calculated resistance, weld-metal failure 11 .3.5... thickness 11 .4 .10 Properties of some selected adhesives 11 .4 .11 Resistance calculations for bonded joints 11 .4 .12 Testing of prototype joints 12 Fatigue 12 .1 General description 12 .2 Possible ways of handling fatigue 12 .3 Checking procedure (safe life) 12 .3 .1 Constant amplitude loading 12 .3.2 Variable amplitude loading 12 .3.3 Design life 12 .3.4 Stress range 12 .3.5 Stress-range spectrum 12 .4 Representative... 12 .4 Representative stress 12 .4 .1 Method A 12 .4.2 Method B 12 .5 Classification of details 12 .5 .1 The BS. 811 8 classification 12 .5.2 Friction-stir welds 12 .5.3 Bonded joints 12 .6 Endurance curves 12 .7 Instructions to fabricator 12 .8 Improvement measures 12 .9 Fatigue of bolts 12 .9 .1 Basic approach 12 .9.2 Endurance curves for steel bolts 12 .9.3 Variation of bolt tension Copyright 19 99 by Taylor & Francis... 1. 1 GENERAL DESCRIPTION 1. 1 .1 The element Aluminium is a metallic element having the chemical symbol Al, with atomic number 13 and atomic weight 27 The nucleus of the atom contains 13 protons and 14 neutrons (a total of 81 quarks) Aluminium is the third most common element in the earth’s crust, coming after oxygen and silicon It makes up 8% of the crust’s total mass and is the most abundant metal 1. 1.2... Britain, 22 000 Spitfires were built between 19 36 and 19 47, and this was only one design from one country 1. 5 ALUMINIUM SINCE 19 45 1. 5 .1 Growth in output The world’s annual output of aluminium in 19 43 at its wartime peak was about two million tonnes (fourteen times the figure for 19 33), all of which was going into warplanes In 19 45 that market dried up and the aluminum industry had quickly to find.. .10 .3.2 Inertias for a section with no axis of symmetry 10 .3.3 Product of inertia 10 .3.4 Inertia of the effective section 10 .3.5 Elastic section modulus 10 .3.6 Radius of gyration 10 .4 Torsional section properties 10 .4 .1 The torque-twist relation 10 .4.2 Torsion constant, basic calculation 10 .4.3 Torsion constant for section containing ‘lumps’ 10 .4.4 Polar inertia 10 .4.5 Warping factor 10 .4.6 Special... of ‘W-section’ from the zeppelin L32, shot down over London in 19 17, is preserved in the Shuttleworth Collection near Bedford (a museum of classic aircraft) Aluminium framed airships continued into the 19 30s, but were abandoned in 19 37 after some spectacular disasters; hydrogen was too dangerous The ill-fated British R1 01 was 230 m long, one of the longest aluminium structures ever built (19 30) Aluminium s . Structural design Standards—Europe. I. Title TA690.D855 19 98 624 .1& apos;826–dc 21 98–39235 CIP ISBN 0 419 15 710 7 (Print Edition) ISBN 0-2 0 3-0 2 81 9-8 Master e-book ISBN ISBN 0-2 0 3 -1 344 9-4 (Glassbook. arising 11 .1. 7 Joints in tension, fastener resistance 11 .1. 8 Interaction of shear and tension 11 .1. 9 Comparisons 11 .1. 10 Joints made with proprietary fasteners 11 .2 Mechanical joints (friction-grip) 11 .2 .1. adhesive 11 .4.6 Creep 11 .4.7 Peeling 11 .4.8 Mechanical testing of adhesives 11 .4.9 Glue-line thickness 11 .4 .10 Properties of some selected adhesives 11 .4 .11 Resistance calculations for bonded joints 11 .4 .12