Pre-stressed concrete [antikvár]

PREFACEPre-stressed concrete is undoubtedly one of the major civil engineering developments of the last twenty years and is the subject of a constantly increasing number of books. In adding the present work to this growing collection the writers have considered the needs of two classes of reader: first the student for university or professional examinations, second the practising designer. The former is now expected to study the rudiments of pre-stressed concrete, while the latter, in many instances, requires a refresher course to acquire techniques not included in his original training.The common need of both is for an exposition of the basic principles which apply to all types of pre-stressed concrete structure. This is provided by Part I of the book. Wherever possible, principles are established theoretically, but constant reference is made to experimental work to confirm and amplify theoretical conclusions. Examples are provided after each chapter in this section, for the student to work himself.Part II deals with the design of simply supported beams, which constitute the greater part of the pre-stressed work hitherto completed. Here the aim is to bridge the gap between principles and practice, using the former as the basis of a procedure that can be carried out in the design office. The maximum possible use is made of formulae, tables and graphs to reduce labour, while the notation is based upon the recommendations of the First Report of the Institution of Structural Engineers. It is hoped that this section of the book will be of particular .value to those embarking for the first time on the design of pre-stressed beams.Part III provides an introduction to some of the more specialised types of pre-stressed structure. The extent of the field has made it' impossible to present more than an outline of the main principles, but there is sufficient to give the reader a grounding, and to enable him to use the more detailed literature now becoming available, some of which is quoted as references after each chapter.The writers are indebted to all who have permitted them to quote from their published work, the references of which have been given as fully as possible. They also gratefully acknowledge the help given by Dr R. Jones, Dr J. D. O'Keefe and Ir A. Kuyper in reading parts of the manuscript, by Mr Charles C. Zollman in compiling the list of American notation and by Mrs M. Westwood in the preparation of the typescript.The book has been written in the belief that principles are more important than details, omitting much of the purely descriptive material usually found in books on pre-stressed concrete. It is offered in the hope that it will provide engineers with a sound foundation upon which to base their own personal contribution to the future development of pre-stressing.R. H. E.E. W. B.v