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An introduction to seismic isolation
Book reviews chapters, arranged under the three headings: specifications and analysis; practical implementation and use; verification and bench marking problems. Many of the chapters represent comprehensive surveys of the present position in research and development and the inclusion of such work in specifications in Europe, the United States and Australia. The key issue addressed is whether it is feasible to eliminate the need for memberby-member design checks using interaction equations by so arranging the computer-based global analysis of the whole frame that it effectively covers member behaviour. The motivation for this is the ever increasing power of computers, the ability at research level to conduct sophisticated frame analyses that include: spread of plasticity, instability, three-dimensional behaviour and imperfections and the realization that working with the set of forces obtained from a lesser frame analysis in conjunction with the ultimate strength member interaction expressions for checking resistance under a given set of end forces may well be inconsistent. The opening paper by the editors sets out the background to the topic, lists all the effects that might be included, considers the hierarchy of analysis methods available and illustrates the potential advantages of a more advanced approach using a 10-storey rigid jointed sway frame for which most members are reduced by at least one serial size as compared with the design using the present United States approach. They also expose some of the concerns attached to a move to greater complexity in design. David Anderson (UK), Murray Clarke et al. (Australia) and Don White et al. (USA) then summarize the current positions in Europe, Australia and the United States, respectively, showing that whilst research capabilities are very similar, the provisions in specifications for use of socalled advanced analysis appears to be very much a function of timing. Thus the most recent 1990 Australian code is the most liberal, although the provisions of EC3 are not dissimilar in their intent, whilst the 1986 AISC specification does not presently recognize this form of approach. Two papers from practitioners then discuss the implementation of advanced analysis in the design office, focusing on as yet unconsidered areas such as the selection of the most critical load cases for design, nonproportional loading, connection design and verification of the software being used. The final pair of major papers deal with the checking of software suitable for use in advanced analysis by means of comparison against standard solutions for a range of well-established frame examples. Each of the three sections is completed by summary papers, synthesizing the results of the actual workshop discussion for the benefit of nonattendees.
233 This volume represents a valuable stateof-the-art report on a subject that is currently receiving a significant measure of attention from both the research and specification writing communities in various parts of the world. It therefore provides an opportunity to compare and contrast the differing views and should rank as essential reading for those concerned with either research into the behaviour of multistorey steel frame structures or those involved with design at an advanced level.
D. A. Nethercot Fundamentals of structural analysis Harry H. West (with computer software by Louis F. Geschwindner) John Wiley & Sons, New York, 1993, Hardback, 550 pages, £67.00. Paperback 716 pages, £21.95
This is a teaching text devoted entirely to the well-established methods of linear elastic analysis of truss, beam and frame structures which have been an essential part of civil and structural engineering courses for many years. The main sections of the book deal with: analysis of statically determinate structures, elastic deformation of (statically determinate) structures, analysis of statically indeterminate structures, and matrix methods of analysis. Most effort is devoted to evaluating the internal forces and the deflections due to applied forces and temperature changes. All well-known hand methods are given, including: virtual work, Castigliano's theorems, complementary energy, the moment-area method, Clapeyron's three-moment equation, column analogy, slope deflection and moment distribution. The use of influence lines is presented for statically determinate structures and the stiffness and flexibility methods of matrix analysis are also given. Approximately half of the book is devoted to examples. There are 119 worked examples and 413 problems for the reader to try for which the answers are given. A disk is included which contains six teaching orientated computer programs. The first section called 'Orientation' contains short items including the history of the subject, structural forms, loading conditions and building materials. It also introduces concepts such as free-body diagrams, the principle of superposition and virtual work and energy principles. The historical section, although tantalisingly brief, is particularly welcome. The choice of photographs is very appropriate and is likely to inspire readers to grapple with the concepts developed in the book. Because the availability of computers is reducing the need for hand numerical calculations, there is pressure in modern cur-
ricula to reduce emphasis on precisely the topics presented in the main part of this text. The authors intend its use for a course over two semesters or, if the 'luxury' of a two-semester course is no longer available, over one semester by selection of parts which coincide with the objectives of such a course. There is not very much discussion included of assumptions in the theory. Change of geometry effects including buckling and nonlinearity including plastic theory are not broached. Hence unless students proceed to study the subject at greater depth at a later date, they are not going to appreciate some of the shortcomings of the classical methods, nor are they going to know when they need to be wary of the answers from standard computer packages for linear elastic analysis of structures. The six teaching orientated computer programs included are professionally presented in an attractive spreadsheet format and yield computerized solutions to specific types of manual analyses covered in the text. Students would find these programs most useful for checking their own manual solutions to problems. Some of the programs, e.g. BEAM and SLOPE are unusual in that they adopt an iterative approach requiring the student to guess the magnitude of shear force and bending moment/rotation and deflection at the starting end of a beam and then modify these on the basis of the calculated values at the other end. Students may find this type of approach confusing. With these provisos, this carefully prepared 698 page book is a worthwhile acquisition for students, even if they may not be required to learn all of the techniques covered. It would also be a useful book for lecturers and those wishing to recap on previously acquired knowledge.
A. Jennings T. J. A. Agar An introduction to seismic isolation R. I. Sldnner, W. H. Robinson and G. H. McVerry John Wiley & Sons, Chichester, UK, 1993, 300 pages, £39.95, ISBN 0 471 93433 X During the last 30 years, research into seismic isolation and its applications has received much attention in both academic and engineering circles. Although there are a fair number of books on the methodology of seismic analysis of structures, this one is unusual because it deals exclusively with structural seismic isolation. It is written by New Zealand experts on the basis of their 25 years of research work in this field, and forms a summary of the history, development and the state-of-the-art of seismic isolation techniques. A major characteristic of this book is its detailed and indepth description of the basic principles,
234
Erratum
methods and engineering applications of seismically isolated structures, based on collaborative work between engineering seismologists and materials scientists. Chapter 1, the introduction, gives a brief account of the development of this field as well as of some basic concepts. Chapter 2 describes the fundamental theory and features of linear and nonlinear isolators. Various maximum seismic responses are summarized in one table and two figures, to illustrate at an intuitive level the different effects of the isolation features of linear or parameter-varied bilinear isolators. Chapter 3 gives the details of various isolation devices and their main features. Special attention is paid to devices invented or perfected by the authors, and which have been applied worldwide, such as lead extrusion dampers and lead-rubber bearings. Chapter 4 comprises a more detailed analysis and expansion of the ideas presented in Chapter 2. Detailed descriptions and comparisons are given for the responses of linearly and bilinearly iso-
lated structures, as well as for substructures either of unisolated or of various isolated structures. Responses of nonclassically damped isolated structures are also investigated for isolators with high damping. Chapter 5 outlines an approach to the seismic design of isolated structures, based on the results developed in previous chapters. Some simple guidelines are summarized, using two examples to clarify the application of the design procedure, which should help designers to choose suitable starting values for parameters. These can then be refined by computation. Chapter 6 presents information on the application of seismic isolation to buildings, bridges and special structures in New Zealand, Japan, the USA, Italy and other countries, with illustrative figures and photos. This book covers a variety of relevant and very efficient methods and their engineering applications up to 1992. These often involve the inventions and experience of the authors and their group. A feature of the book is that difficult mathematics is
avoided in all theoretical derivations. Instead, the mechanism of seismic isolation has been clearly explained, based on some typical models and basic mathematical tools. Many of the figures and tables should prove to be very useful for understanding both the theory and engineering design methods. The worldwide practical applications are instructive, and so this book should be especially helpful to civil, structural and architectural engineers. It should be noted that the main application of this book is for generating initial engineering designs. Detailed engineering analysis of seismic isolation and its associated computations would require reference to other books. The book covers its topic very clearly, is easy to read and good value for money.
Jiahao Lin F. W. W i l l i a m s
Enginee~ng Structures, Vol. 17, No. 3, p. 234, 1995
II~UTTERWQRTH II~E I N E M A N N
0141-0296(95)00056-9
Elsevier Science Ltd Pnnted in Great Britain 0141-0296/95 $10.00+ 0.00
Erratum
' A l o n g - w i n d response o f lattice towers: part 1 - derivation o f expressions for gust response factors' by J. D. H o l m e s
(Engineering Structures 1994, 16, 2 8 7 - 2 9 2 ) . Equation (10) should h a v e read ' (',h o(z,,z2)[l - (tz,/h)][1
Bs = ' ~l,,J
(tz~/h)l(z,/h)=(z2/h) ~ d(zl/h)d(zJh)
{f:,h
[1-t(zlh)](z/h)"d(z/h)} 2
(10)
E q u a t i o n (14) should h a v e read gB = g , [1 + (g, r(B,)l/2/4)]
(14)
233 This volume represents a valuable stateof-the-art report on a subject that is currently receiving a significant measure of attention from both the research and specification writing communities in various parts of the world. It therefore provides an opportunity to compare and contrast the differing views and should rank as essential reading for those concerned with either research into the behaviour of multistorey steel frame structures or those involved with design at an advanced level.
D. A. Nethercot Fundamentals of structural analysis Harry H. West (with computer software by Louis F. Geschwindner) John Wiley & Sons, New York, 1993, Hardback, 550 pages, £67.00. Paperback 716 pages, £21.95
This is a teaching text devoted entirely to the well-established methods of linear elastic analysis of truss, beam and frame structures which have been an essential part of civil and structural engineering courses for many years. The main sections of the book deal with: analysis of statically determinate structures, elastic deformation of (statically determinate) structures, analysis of statically indeterminate structures, and matrix methods of analysis. Most effort is devoted to evaluating the internal forces and the deflections due to applied forces and temperature changes. All well-known hand methods are given, including: virtual work, Castigliano's theorems, complementary energy, the moment-area method, Clapeyron's three-moment equation, column analogy, slope deflection and moment distribution. The use of influence lines is presented for statically determinate structures and the stiffness and flexibility methods of matrix analysis are also given. Approximately half of the book is devoted to examples. There are 119 worked examples and 413 problems for the reader to try for which the answers are given. A disk is included which contains six teaching orientated computer programs. The first section called 'Orientation' contains short items including the history of the subject, structural forms, loading conditions and building materials. It also introduces concepts such as free-body diagrams, the principle of superposition and virtual work and energy principles. The historical section, although tantalisingly brief, is particularly welcome. The choice of photographs is very appropriate and is likely to inspire readers to grapple with the concepts developed in the book. Because the availability of computers is reducing the need for hand numerical calculations, there is pressure in modern cur-
ricula to reduce emphasis on precisely the topics presented in the main part of this text. The authors intend its use for a course over two semesters or, if the 'luxury' of a two-semester course is no longer available, over one semester by selection of parts which coincide with the objectives of such a course. There is not very much discussion included of assumptions in the theory. Change of geometry effects including buckling and nonlinearity including plastic theory are not broached. Hence unless students proceed to study the subject at greater depth at a later date, they are not going to appreciate some of the shortcomings of the classical methods, nor are they going to know when they need to be wary of the answers from standard computer packages for linear elastic analysis of structures. The six teaching orientated computer programs included are professionally presented in an attractive spreadsheet format and yield computerized solutions to specific types of manual analyses covered in the text. Students would find these programs most useful for checking their own manual solutions to problems. Some of the programs, e.g. BEAM and SLOPE are unusual in that they adopt an iterative approach requiring the student to guess the magnitude of shear force and bending moment/rotation and deflection at the starting end of a beam and then modify these on the basis of the calculated values at the other end. Students may find this type of approach confusing. With these provisos, this carefully prepared 698 page book is a worthwhile acquisition for students, even if they may not be required to learn all of the techniques covered. It would also be a useful book for lecturers and those wishing to recap on previously acquired knowledge.
A. Jennings T. J. A. Agar An introduction to seismic isolation R. I. Sldnner, W. H. Robinson and G. H. McVerry John Wiley & Sons, Chichester, UK, 1993, 300 pages, £39.95, ISBN 0 471 93433 X During the last 30 years, research into seismic isolation and its applications has received much attention in both academic and engineering circles. Although there are a fair number of books on the methodology of seismic analysis of structures, this one is unusual because it deals exclusively with structural seismic isolation. It is written by New Zealand experts on the basis of their 25 years of research work in this field, and forms a summary of the history, development and the state-of-the-art of seismic isolation techniques. A major characteristic of this book is its detailed and indepth description of the basic principles,
234
Erratum
methods and engineering applications of seismically isolated structures, based on collaborative work between engineering seismologists and materials scientists. Chapter 1, the introduction, gives a brief account of the development of this field as well as of some basic concepts. Chapter 2 describes the fundamental theory and features of linear and nonlinear isolators. Various maximum seismic responses are summarized in one table and two figures, to illustrate at an intuitive level the different effects of the isolation features of linear or parameter-varied bilinear isolators. Chapter 3 gives the details of various isolation devices and their main features. Special attention is paid to devices invented or perfected by the authors, and which have been applied worldwide, such as lead extrusion dampers and lead-rubber bearings. Chapter 4 comprises a more detailed analysis and expansion of the ideas presented in Chapter 2. Detailed descriptions and comparisons are given for the responses of linearly and bilinearly iso-
lated structures, as well as for substructures either of unisolated or of various isolated structures. Responses of nonclassically damped isolated structures are also investigated for isolators with high damping. Chapter 5 outlines an approach to the seismic design of isolated structures, based on the results developed in previous chapters. Some simple guidelines are summarized, using two examples to clarify the application of the design procedure, which should help designers to choose suitable starting values for parameters. These can then be refined by computation. Chapter 6 presents information on the application of seismic isolation to buildings, bridges and special structures in New Zealand, Japan, the USA, Italy and other countries, with illustrative figures and photos. This book covers a variety of relevant and very efficient methods and their engineering applications up to 1992. These often involve the inventions and experience of the authors and their group. A feature of the book is that difficult mathematics is
avoided in all theoretical derivations. Instead, the mechanism of seismic isolation has been clearly explained, based on some typical models and basic mathematical tools. Many of the figures and tables should prove to be very useful for understanding both the theory and engineering design methods. The worldwide practical applications are instructive, and so this book should be especially helpful to civil, structural and architectural engineers. It should be noted that the main application of this book is for generating initial engineering designs. Detailed engineering analysis of seismic isolation and its associated computations would require reference to other books. The book covers its topic very clearly, is easy to read and good value for money.
Jiahao Lin F. W. W i l l i a m s
Enginee~ng Structures, Vol. 17, No. 3, p. 234, 1995
II~UTTERWQRTH II~E I N E M A N N
0141-0296(95)00056-9
Elsevier Science Ltd Pnnted in Great Britain 0141-0296/95 $10.00+ 0.00
Erratum
' A l o n g - w i n d response o f lattice towers: part 1 - derivation o f expressions for gust response factors' by J. D. H o l m e s
(Engineering Structures 1994, 16, 2 8 7 - 2 9 2 ) . Equation (10) should h a v e read ' (',h o(z,,z2)[l - (tz,/h)][1
Bs = ' ~l,,J
(tz~/h)l(z,/h)=(z2/h) ~ d(zl/h)d(zJh)
{f:,h
[1-t(zlh)](z/h)"d(z/h)} 2
(10)
E q u a t i o n (14) should h a v e read gB = g , [1 + (g, r(B,)l/2/4)]
(14)