The Design Of Structures Of Least Weight

International Series of Monographs in Aeronautics and Astronautics, Division 1: Solid and Structural Mechanics, Volume 8: The Design of Structures of Least Weight focuses on the design of structures. This book reviews the considerations that determine the minimal structure weight and illustrates how these considerations may be expected to influence design. Topics discussed include the theory in design, structure loading coefficients and struts, wide struts, panels, and design of beams to transmit pure bending. The design of cantilevers, detail design of braced frames, basic theory of layout, and layout in practical design are also deliberated in this publication. This volume is recommended for design engineers and specialists intending to acquire knowledge of design structures of least weight.

ICSAS '99 - The Fourth International Conference on Steel and Aluminium Structures was a sequel to ICSAS '87 held in Cardiff, UK, to ICSAS '91 held in Singapore and to ICSAS '95 held in Istanbul, Turkey. The objective of the conference was to provide a forum for the discussion of recent findings and developments in the design and construction of various types of steel and aluminium structures. The conference was concerned with the analysis, modelling and design of light-weight or slender structures in which the primary material is structural steel, stainless or aluminium. The structural analysis papers presented at the conference cover both static and dynamic behaviour, instability behaviour and long-term behaviour under hygrothermal effects. The results of the latest research and development of some new structural products were also presented at the conference. A total of 76 papers and 30 posters were presented at the conference by participants from 36 countries in all 6 continents.

The report considers the state of the art in methods of structural optimization. Mathematical programming based methods, while extremely successful with problems of moderate size tend to become prohibitively costly when applied to large scale structures. A novel approach to the weight optimization of indeterminate structures under multiple loading conditions with strength and displacement constraints has been developed and is presented herein. Using this method significant improvements in computational time have been achieved over direct numerical search methods. In some cases the numbers of iterations required to determine the least weight have been reduced by factors of over 20. The rate of convergence is independent of problem size permitting application to large scale structures. Examples of application of the new approach to a number of problems are included.

The book covers new developments in structural topology optimization. Basic features and limitations of Michell’s truss theory, its extension to a broader class of support conditions, generalizations of truss topology optimization, and Michell continua are reviewed. For elastic bodies, the layout problems in linear elasticity are discussed and the method of relaxation by homogenization is outlined. The classical problem of free material design is shown to be reducible to a locking material problem, even in the multiload case. For structures subjected to dynamic loads, it is explained how they can be designed so that the structural eigenfrequencies of vibration are as far away as possible from a prescribed external excitation frequency (or a band of excitation frequencies) in order to avoid resonance phenomena with high vibration and noise levels. For diffusive and convective transport processes and multiphysics problems, applications of the density method are discussed. In order to take uncertainty in material parameters, geometry, and operating conditions into account, techniques of reliability-based design optimization are introduced and reviewed for their applicability to topology optimization.

I am very much aware that it is an act of extreme rashness to attempt to write an elementary book about structures. Indeed it is only when the subject is stripped of its mathematics that one begins to realize how difficult it is to pin down and describe those structural concepts which are often called' elementary'; by which I suppose we mean 'basic' or 'fundamental'. Some of the omis sions and oversimplifications are intentional but no doubt some of them are due to my own brute ignorance and lack of under standing of the subject. Although this volume is more or less a sequel to The New Science of Strong Materials it can be read as an entirely separate book in its own right. For this reason a certain amount of repetition has been unavoidable in the earlier chapters. I have to thank a great many people for factual information, suggestions and for stimulating and sometimes heated discussions. Among the living, my colleagues at Reading University have been generous with help, notably Professor W. D. Biggs (Professor of Building Technology), Dr Richard Chaplin, Dr Giorgio Jeronimidis, Dr Julian Vincent and Dr Henry Blyth; Professor Anthony Flew, Professor of Philosophy, made useful suggestions about the last chapter. I am also grateful to Mr John Bartlett, Consultant Neurosurgeon at the Brook Hospital. Professor T. P. Hughes of the University of the West Indies has been helpful about rockets and many other things besides. My secretary, Mrs Jean Collins, was a great help in times of trouble. Mrs Nethercot of Vogue was kind to me about dressmaking. Mr Gerald Leach and also many of the editorial staff of Penguins have exercised their accustomed patience and helpfulness. Among the dead, l owe a great deal to Dr Mark Pryor - lately of Trinity College, Cambridge - especially for discussions about biomechanics which extended over a period of nearly thirty years. Lastly, for reasons which must surely be obvious, l owe a humble oblation to Herodotus, once a citizen of Halicamassus.

The book covers the theory of Michell structures being the lightest and fully stressed systems of bars, designed within a given domain, possibly within the whole space, transmitting a given load towards a given support. Discovered already in 1904 by A.G.M. Michell, the structures named after him have attracted constant attention due to their peculiar feature of disclosing the optimal streams of stresses equilibrating a given load and thus determining the optimal layout of bars. The optimal layouts emerge from among all possible structural topologies, thus constituting unique designs being simultaneously light and stiff. The optimal structures turn out to be embedded in optimal vector fields covering the whole feasible domain. Key features include: a variationally consistent theory of bar systems, thin plates in bending and membrane shells; recapitulation of the theory of optimum design of trusses of minimum weight or of minimal compliance; the basis of 2D Michell theory for a single load case; kinematic and static approaches; 2D benchmark constructions including Hemp’s structures and optimal cantilevers; L-shape domain problems, three forces problem in 2D, bridge problems; revisiting the old - and delivering new - 3D benchmark solutions; extension to multiple load conditions; Prager-Rozvany grillages; the theory of funiculars and archgrids; the methods of optimum design of shape and material inspired by the theory of Michell structures, industrial applications. The book can be useful for graduate students, professional engineers and researchers specializing in the Optimum Design and in Topology Optimization in general.

This book brings together key works of the noted architect and architectural theorist Christopher Alexander (1936–2022), many of which have not been published before. The book contains twenty-five essays and other works, many chosen from the newly organized Christopher Alexander archive, providing a window into the ideas and thought process of one of the most innovative architectural thinkers of the twentieth century. The items span Alexander’s fifty-year career, beginning with an early version of his PhD dissertation based on fieldwork in India, continuing to fifteen years in the development of A Pattern Language, one of the best-selling books in the history of architecture, and proceeding to the writing of The Nature of Order, Alexander’s four-volume masterwork, and beyond. The writings combine theory and descriptions of practice, and together support a blueprint for the development of a new, humane way of building, while also providing a window into the mind of an extraordinary thinker, teacher and professional.