Design of Steel Frames for Buildings

FIFTY YEARS AGO the structural use of timber was entirely governed by the known properties of the raw material in its natural state. These properties had become known by trial and error and in consequence were defined by limitations rather than potentialities. The natural limitations on available dimensions, weakness in shear, inability to make a good tension joint or to maintain continuity around bends or at the ends of pieces, no effective control over moisture movement, no systematic evaluation of strength, no constructive knowledge of pathology and treatment, no apparent escape from unidirectional stress distribution : all factors which operated in the development of empirical techniques and the establishment of a fairly rigid code of traditional practice. P.O. Reece

THE THEORETICAL analysis of the behaviour of engineering structures, as we know the subject today, can be said to date effectively from the end of the 18th century. Monumental structures had of course been built long before that and their impressive remains can still be seen in Egypt and Mesopotamia and especially in countries which were formerly part of the Roman Empire. But, so far as is known, the engineer- architects who built these great works had no theoretical principles to guide them and relied only upon trial and experiment and their own genius. Much the same can be said of the builders of the great cathedrals of Europe who carried the art of constructing masonry arches, vaults and buttresses to a level that has never been surpassed. It was not until the Renaissance that men began to enquire in a systematic way into the laws that govern structural behaviour but even then progress was slow for many years. The pace quickened in the 18th century especially in France where the "ingenieurs des ponts et chausstes" were attempting to apply the methods of mathematics systematically to the design and construction of the structures for which they were responsible. The foundation of the "Ecole des Ponts et Chaussdes" in 1747 marks the beginning of the practice of training engineers to use this scientific approach to their work, and the interchange of men and ideas between this school and the military corps of engineers was extraordinarily productive. The most important figure of this period is Coulomb whose work on the bending of beams, on torsion, on friction and on the stability of retaining walls was an immense step forward. In his efforts to deal with the problems of structural statics by scientific methods, but without losing sight of practical requirements, Coulomb was the first to deal with structural analysis in a recognisably modern manner. Professor J.A.L. Matheson

Photographs of Mr. L. E. Kent, Mr. J. Singleton-Green, Lt.-Col. G. W. Kirkland, Mr. E. N. Underwood and Mr. T. Bredin