A Study of the Circular-arc Bow Girder

Abstract

THIS book treats of the difficult problem of girders forming a circular arc in plan such as are often used to support the balcony of a theatre. The principles on which the general problem may be solved are given in the early portion of the volume, and are amplified from a paper read by Prof. Gibson before the Royal Society of Edinburgh in 1912. Values of the end fixing moments and reactions have been calculated for the more important practical cases, and these values, together with typical bending moment diagrams which are given, will be found useful aids to the designer. The authors have carried out experiments with a view of checking the theoretical investigation, and remarkable agreement is shown. Up to the appearance of this volume there has been no data available for the torsional rigidity of beams of ordinary commercial section, and part of the investigation undertaken by the authors has been the experimental determination of the product CJ (i.e., modulus of rigidity × equivalent polar moment of inertia) for such sections. Mathematical calculations in such cases present insuperable difficulties, and the experimental work given in the book is an interesting and valuable contribution to our knowledge of materials. A chapter on the general principles of design of the bow-girder is included, and will be of service to the practical designer, to whom a considerable portion of the volume will be sealed on account of necessarily complicated mathematical treatment. The authors may be congratulated on the success with which they have solved a very difficult practical problem.

A Study of the Circular-arc Bow Girder.

By Prof. A. H. Gibson E. G. Ritchie. Pp. viii + 80. (London: Constable and Co., Ltd., 1914.) Price 10s. 6d. net.