Engineers are rightly cautious in reviewing new techniques of structural design and indeed are sometimes regarded as being too conservative in their acceptance of the results of engineering research. It seems to the writer however that any further progress in the science of steelwork design can be only made on the basis of new assumptions. Arthur Bolton
In a previous paper' we have pointed out the desirability of being able to calculate the critical load of building frames. This paper shows how the sway critical load of any symmetrical single bay frame may be obtained. It also gives the results of numerical calculations for a particular case and an extension to many bay frames. W. Merchant
THE PRESIDENT proposed a vote of thanks to the Authors for the skill with which they had put together the information presented in the paper and the clarity of the photographs and drawings and descriptions they had given.
MR. K. C. DAVEY (Associate-Member): On the basis of the graphs shown in Fig. 10, I have found it interesting to extract some figures and consider them further, to arrive at a relative cost relationship between them as opposed to the purely weight relationship. I append below in tabulated form comparative cost and weight figures for trusses of spans considered by the author at spacings varying between 12 ft. 6 in. and 20 ft. in increments of 2 ft. 6 in. The cost is expressed in the form of equivalent units and for this purpose I have assumed that the relationship between the prices of individual components of the building is as shown below.
THE historical development of methods of analysis, for use in the design of continuous frames, is traced from the introduction of the theorem of three moments, almost a hundred years ago, to the contemporary application of electronic digital computers. The types of frame under consideration range from the highly redundant skeleton of a city building to the highly deformable structure of a large span single storey building or hangar. The analysis is restricted by the conventions of practical structural engineering design, namely that axial deformations of frame members may be discounted, and that columns are not so slender as to raise problems of elastic instability. The principal methods-moment-area, slope-deflection, strain-energy, moment-distribution, relaxation, etc.-are briefly summarised, and a case is presented for the need of more than one method to meet different design requirements. E.H. Bateman