The purpose of this book is to provide in a single volume an adequate coverage of those principles of strength of materials and elementary theory of structures that are usually included, in one form or another, in courses followed by students of architecture, building, civil engineering, structural engineering and allied disciplines. The topics discussed should prove to be equally relevent to the requirements of both full-time and part-time students engaged in study leading to the award of various certificates, diplomas and degrees. The choice and presentation of the subject matter reflects the author's central philosophy that the qualitative aspects of the behavioural characteristics of structures are of primary importance. Understanding structural behaviour is the key to understanding structural calculations and design methods. There should be no mystique and very little needs to be taken for granted. The student should take every opportunity offered in laboratory and other practical periods to examine, especially from a qualitative point of view, the behaviour of various structural elements under load. Careful examination of phenomena observed in the laboratory, both expected and unexpected, will often provide a valuable insight into the theoretical reasoning which attempts to explain the same phenomena quantitatively. Lecturers and teachers should make liberal use of classroom demonstrations and of impromptu experiments. It is intended that this book be used as a direct teaching text, thus obviating the need for single-sheet handouts and the copying out of assignment exercises. The author has assumed, quite rightly, that lecturers and teachers are perfectly capable of providing detailed explanations and will be able to answer queries, help with difficulties, etc. The text therefore sets out to provide the essential theories, formulae and principles in as simple and straightforward a manner as is consistent with clarity and ease of reading. Extensive use is made of worked examples in the text, the solutions being accompanied by explanatory remarks. At the end of each chapter practice exercises are given to cover the whole of the work done in the chapter. Answers to these exercises are provided at the end of the book.