H. Eggert, W. Kauschke
Structural Bearings
irnst &Sohn
Helmut Eggert, Wolfgang Kauschke
Structural
Bearings
irnst &Sohn
Dr.-lng. Helmut Eggert Lenzelpfad 32 12353 Berlin Germany
Dipl.-lng. Wolfgang Kauschke Starenweg 10
42781 Haan Germany
This book contains 272 figures and 45 tables
Die Deutsche Bibliothek - CIP-Cataloguing-in-Publication-Data
A catalogue record for this publication is available from Die Deutsche Bibliothek
ISBN 3-433-01238-5
© 2002 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH, Berlin
All rights reserved, especially those of translation into other languages. No part of this book shall be reproduced in any form - i.e. by photocopying, microphotography, or any other process - or be rendered or translated into a language useable by machines, especially data processing machines, without the written permission of the publisher.
Typesetting: Manuela Treindl, Regensburg Printing: betz-druck GmbH, Darmstadt
Binding: Litges & Dopf Buchbinderei GmbH, Heppenheim Printed in Germany
Preface
Organization of this book
Like its German edition, this book has nine main chapters. These chapters are broken down in the list of contents into a maximum of five sec-tion levels. In the text, some further subdivision is used to improve ease of reading and refer-encing. The use of a glossary, which provides a brief definition of subject index terms, is not very common in technical books; we have in-cluded one in this book in the hope that it will aid readers in their understanding of this spe-cial subject.
Contents
This book should provide sufficient answers to typical questions related to the design and con-struction of bridges and industrial structures. Topics covered include:
- how to support a structure (chapter 2), - which loads are transferred from the
structure into the bearing (chapter 3), - what types of bearings are available
(chapter 4), and
- which technical guidelines must be taken into account (chapter 5).
Chapter 6 provides information on the Appro-vals of the German Institute for Civil Structures (Deutsches Institut für Bautechnik, DIBt). Reports dealing with research and scientific problems related to the subject of bearings are listed in chapter 7.
This book is meant to serve as a tool for the design engineer, architect, or engineer writing specifications, for the designing, calculating, and testing engineer, and for the civil contrac-tor.
The design of a structure will usually a priori define - whether intended or not - the support system. Neglect of this connection can later
result in damage if, for example, the necessary support system cannot be realized.
Costs incurred by damage to bearings can be very high if complete replacement of the con-structions is necessary. Examples from Ger-many include:
- unsuitable roller bearings, - unsuitable top sealing, - installation mistakes, and
- material mistakes (essential elastomeric bearings).
The most frequent bearing damage is corrosion damage.
Serious economic damage can also be caused by corrosion in other fields.
Chapter 4 contains proposals for construction with low levels of corrosion.
The word "bearing" has different technical meanings. This book refers to bearings as tech-nical parts that are manufactured in special plants and used in structures as an interface between the substructure and superstructure. It transfers loads in a defined way and allows for motion or displacements. The different types of bearings are characterized by their function as well as their main material (see section 1.2.4). The glossary provides further definitions. Centering elements built together with the struc-ture, such as concrete hinges, are not covered in this book.
This book concentrates on bridges, the classic application of the bearing technique. It mainly deals with nondynamic applications but also gives some additional information on dynamic influences (see sections 2.2.5, 2.2.6, and 3.4). February 2002 Helmut Eggert
Preliminary remarks
We wish to thank everyone who has helped us produce this book, particularly our wives for their patience and
Dr. Günter Hüffmann for his excellent translation.
Contributors to this book:
Hans-Peter Rieckmann (section 3.3)
Günter Hüffmann/Karl-Heinz Reinsch (section 3.4) Armin Gerber/Jochen Wiedemeyer (section 7.3.1) Karl-Heinz Hehn (section 7.3.2)
Section 4.5 was revised for this edition by Florian Deischl
Contents
Preface V
Preliminary remarks VI
1 Introduction 1
1.1 History 1 1.2 Terms and descriptions 1
1.2.1 Support and bearings as part of the structure 1
1.2.2 Roll-off, sliding, deformation 2 1.2.3 Bearing, hinge, pendulum 4 1.2.4 Bearing definitions 5 1.3 Basic guidelines for selecting the support system 5
1.4 Bearing motion 6 1.4.1 General 6 1.4.2 Displacements caused by temperature 10
1.4.3 Displacements caused by prestressing, creep, and shrinkage 10 1.4.4 Displacements in the bearings caused by outer loads 11
1.4.5 Support rotation 11 1.5 Bearing symbols 12 1.6 Rotational resistance 12 1.6.1 Basic moment 12 1.6.2 Restoring moment and rotation 14
1.6.3 Other dependencies 15 1.6.4 Influence of horizontal forces 15
1.6.5 Influence of the restoring moment on the structure 17
2 Structure and bearing system 19
2.1 Introduction 19 2.2 Bridges 20 2.2.1 Influence of different bridge cross sections 20
2.2.2 Influence of the bridge plan view 22 2.2.2.1 Single span bridges (orthogonal) 22
2.2.2.2 Single span skew bridge 23 2.2.2.3 Two span bridge (orthogonal) 23 2.2.2.4 Two span skew bridge 24
VIII Contents
2.2.2.5 Continuous beams (orthogonal) 24 2.2.2.6 Continuous beams (curved) 24 2.2.3 Examples of bearing systems 27 2.2.3.1 Single span bridge (orthogonal) 27
2.2.3.2 Two span skew bridge 28 2.2.3.3 Continuous beams (orthogonal) 28
2.2.3.4 Continuous beams (curved) 28
2.2.4 Subsoil influence 36 2.2.5 Vibration control of buildings 37
2.2.6 Structures in seismic zones 37 2.2.7 From specification to installation of bearings 38
3 Structure and bearing loads 41
3.1 From a hinge to a bearing 41
3.2 Bridge analysis 42 3.2.1 Introduction 42 3.2.2 Transfer of vertical loads 45
3.2.3 Transfer of horizontal loads in longitudinal bridge direction 46 3.2.4 Transfer of horizontal loads in lateral bridge direction 48
3.2.5 Loads depending on the type of bearing 49
3.2.6 Bearing motion 49 3.2.7 Stability (protection against sliding, overturning, and uplift) 50
3.2.8 Safety considerations based on bearing properties 52 3.3 Influence of bearings on the stability of constructions 54
3.3.1 General 54 3.3.2 Boundary and special conditions for bearings 55
3.3.3 Buckling lengths of columns 57
3.3.3.1 General 57 3.3.3.2 Single columns 58 3.3.3.3 Straight bridges with columns of differing lengths 59
3.3.3.4 Straight bridge with only two column types 61 3.3.3.5 Straight bridges with rocker bearings 62
3.3.3.6 Curved bridges 62 3.3.3.7 Elastic restraint, variable bending resistance, and longitudinal force 63
3.3.4 Proof of total system safety 64 3.4 Bearings with high vertical flexibility 64
3.4.1 Bearings for vibration control 64 3.4.1.1 Basics of vibration and structure-borne noise control 64
3.4.1.2 Elements for vibration isolation 67
3.4.1.2.1 Coil spring elements 67 3.4.1.2.2 Viscodampers 70 3.4.1.2.3 Elastomeric bearings 73 3.4.1.2.4 Comparison of coil springs and elastomeric bearings 74
3.4.2 Bearings for protection against settlements/subsidences 74
3.4.3 Elastic support of buildings 76
Contents IX
3.4.3.2 Vibration control (mechanical vibrations) 76
3.4.3.3 Structure-borne noise control 78 3.4.3.4 Selection of elastic bearings for vibration and structure-borne noise control 78
3.4.3.5 Base isolation of entire buildings 79 3.4.3.6 Spring support of partial building areas (room-in-room) 81
3.4.3.7 Seismic base isolation 82 3.4.3.8 Track-bed isolation 84
4 Bearing types 87
4.1 Basic remarks 87 4.2 General design and dimensioning rules 88
4.2.1 Materials 88 4.2.1.1 Types of steel for bearing parts 88
4.2.1.2 Elements for bolt connections according to EC3-1-1 89 4.2.1.3 Peculiarities of connectors made of stainless steel 90
4.2.1.4 Welding 92 4.2.2 Sectional data and degrees of freedom 92
4.2.3 Rules for dimensioning 93
4.2.3.1 Bearing plates 93 4.2.3.2 Bolt connections 93 4.2.3.3 Weld connections 94 4.2.3.4 Pressure in the bearing joints 95
4.2.3.5 Verification of static equilibrium 97 4.2.3.6 Practical advice on the transmission of horizontal loads in the bearing joints . . . . 98
4.2.3.7 Anchoring through stud bolt dowels 100
4.2.3.8 Corrosion protection 101 4.3 Fixed bearings 101 4.3.1 Introduction 101 4.3.2 Steel point rocker bearings 104
4.3.3 Pot bearings 109 4.3.4 Spherical bearings 113 4.3.5 Fixed deformation bearings 115
4.3.5.1 General information 115 4.3.5.2 Journal bearings 116 4.3.5.3 Pot deformation bearings 117
4.4 Sliding bearings 118 4.4.1 Introduction 118 4.4.2 Guidelines 120 4.4.3 Sliding bearing system 120
4.4.4 Dimensioning of the bearing plates 121 4.4.4.1 Sliding plate and PTFE-housing 121 4.4.4.2 Design of the PTFE-housing 123 4.4.5 Point rocker sliding bearings 125
4.4.5.1 Introduction 125 4.4.5.2 Design and dimensioning 126
X Contents
4.4.5.4 Load eccentricities for the analysis of the stresses in the PTFE sliding surface .. 127 4.4.5.5 Load eccentricities for the analysis of the upper and lower bearing joints 128
4.4.6 Pot sliding bearings 128
4.4.6.1 Basics 128 4.4.6.2 Design and dimensioning 128
4.4.6.3 Design basics for the PTFE-housing 129 4.4.6.4 Load eccentricities for pressure analysis in the PTFE sliding surface 131
4.4.6.5 Load eccentricities for the analysis of the upper and lower bearing joint 131
4.4.7 Spherical bearings 131
4.4.7.1 Basics 131 4.4.7.2 Design and dimensioning 132
4.4.7.3 Design of the PTFE-housing 132 4.4.7.4 Load eccentricities for the analysis of stresses in the PTFE sliding surfaces . . . . 132
4.4.7.5 Load eccentricities for the analysis of the upper and lower bearing joints 133
4.4.7.6 Stresses in the PTFE guide surfaces 133 4.4.8 Deformation sliding bearings 133
4.4.8.1 Basics 133 4.4.8.2 Design and dimensioning 134
4.4.8.3 Design basics for the PTFE-housing 134 4.4.8.4 Load eccentricities for the analysis of the pressure in the PTFE sliding surface . 136
4.4.8.5 Load eccentricities for the analysis of the upper and lower bearing joints 136
4.4.9 Elastomer sliding bearings 136
4.4.9.1 Basics 136 4.4.9.2 Design and dimensioning 137
4.4.9.3 Design of the PTFE-housing 137 4.4.9.4 Load eccentricities for the analysis of the pressure in the PTFE sliding surface . 137
4.4.9.5 Load eccentricities for the analysis of the upper and lower bearing joints 137
4.5 Deformation bearings 137 4.5.1 History 138 4.5.2 Applicable material 138 4.5.3 Physical properties 140 4.5.3.1 Rubber elasticity 140 4.5.3.2 Shear modulus 141 4.5.3.3 Elasticity modulus 146 4.5.3.4 Stability 146 4.5.3.5 Creep and relaxation 146
4.5.3.6 Stick friction 147 4.5.4 Future design rules 151 4.5.5 Special reinforced elastomeric bearings 153
4.5.5.1 Pre-adjusted elastomeric bearings with presetting 153 4.5.5.2 Elastomeric bearings with low rotation resistance 153
XI
5 Standards 155
5.1 Preliminary remarks 155 5.2 Imprint from EN 1337-1: General design rules 156
5.3 Remarks on EN 1337-2: Sliding elements 179 5.4 Remarks on the draft of EN 1337-3: Elastomeric bearings 181
5.5 Remarks on the draft of EN 1337-5: Pot bearings 187 5.6 Remarks on EN 1337-7: Spherical and cylindrical PTFE-bearings 190
5.7 Remarks on the draft of EN 1337-8: Guide bearings and restraint bearings 192 5.8 Remarks on the draft of EN 1337-10: Inspection and maintenance 197 5.9 Imprint of EN 1337-11: Transport, storage and installation 200
6 Approvals 217
6.1 German Approval of sliding bearings (example) 218 6.2 German Approval of spherical bearings (two examples) 235 6.3 Pot bearing: special conditions (in part) and appendices 266 6.4 German Approval of a bearing for vibration control 274
7 Science and research 293
7.1 General 293 7.2 Research reports 293
7.2.1 Long-term friction and wear tests with sliding bearings, different sliding
surfaces 293 7.2.2 Long-term friction and wear tests with PTFE sliding bearings, III c quality . . . . 294
7.2.3 Investigation of friction behavior of PTFE through variation of the influence parameters: Sliding speed, pressure, bearing size, total way (wear), bearing
system, load eccentricity 295 7.2.4 Dependence of thickness on the temperature and size of elastomeric bearings .. 295
7.2.5 Rupture tests with bearing plates 298 7.2.6 Permissible horizontal forces for nonanchored bearings 298
7.2.7 Permissible horizontal loads at nonanchored bearings: Supplementary tests
on zinc-coated steel plates 299 7.2.8 On the slip-resistance of nonanchored elastomeric bearings 299
7.2.9 Determination of the characteristic values of the friction coefficients 300
7.2.10 Steel bridge bearing movements 300 7.2.11 Load-bearing capacity and reliability of reinforced concrete compression
members 301 7.2.12 Map of the lowest median daily temperature in Germany 301
XII Contents
7.3 Approval tests 302 7.3.1 Sliding bearing tests 302
7.3.1.1 General 302 7.3.1.2 Results of investigations on PTFE sliding bearings 303
7.3.1.2.1 Model bearings 304 7.3.1.2.2 Reviewed bridge bearings 332
7.3.1.3 Results of investigations with composite sliding bearings 334
7.3.1.3.1 Materials 334 7.3.1.3.2 Testing technique 336 7.3.1.3.3 Tribological behavior 337
7.3.1.4 Summary 338 7.3.2 Pot bearing tests 342
7.3.2.1 General 342 7.3.2.2 Material testing 342 7.3.2.3 Control of finished test bearing 343
7.3.2.4 Weariest 343 7.3.2.5 Determination of the restoring moment 343
7.3.2.6 Ultimate load test 346 7.3.2.7 Permanent load test 347 7.3.2.8 Summary and future work 347
8 Glossary 349
9 Literature 371
9.1 Literature, with brief comments 371
9.1.1 General literature 371 9.1.2 Historical literature 373 9.1.3 Test reports 374 9.1.4 Practical applications 374 9.1.5 Analysis 377 9.2 Cited literature 380 Subject index 389
