MR. KURT H. GERSTLE The author's method of analysing braced frames will be welcomed by structural engineers. This discussion will touch on two different aspects of the paper: First, the effect of column continuity, and, secondly, the suitability of the proposed method to the various example problems presented.
This paper extends previous work by making possible the solution of problems of composite-action between a slab and equally-spaced stiffening beams when the flexural stiffness of the beams varies along their length. Provided that symmetry about the midspan is maintained, no restriction is placed upon the form of variation (the effective depth of the beams being specified numerically at a number of points across the span); Fig. 2 illustrates two kinds of variation which may be expected to occur in practice. D.N. de G. Allen and R.T. Severn
Mr. M.Z. COHN The background of Professor Neal's paper is to outline a very interesting property of redundant structures, which consists in conserving constant deflexions at the point of collapse, above a definite critical value of joint (or support) flexibility.
THE PRESIDENT proposing a vote of thanks to the author, said the subject was fascinating and the Institution was extremely grateful to Mr. Kell for his paper.
The Hardy Cross, or Moment Distribution, method of frame analysis offers interesting possibilities, when used on an automatic digital computer. For a number of years the analysis of elastic hyperstatic frames by computer has been mainly carried out by methods which require the explicit solution of large sets of simultaneous equations. If conventional techniques are used to solve the equations, the storage space required in the memory of the computer is approximately proportional to the square of the number of joints in the frame. This means that in practice, with present-day computers, only relatively simple frames can actually be analysed by these methods.
When an external force is applied to a point in an elastic structure the direction of the deflexion at the point will, in general, deviate from the load line. A general relationship is established connecting the deflexions and deviations caused by forces applied in different directions. A short investigation is made of the deflexions caused at one point by loads applied at some second point. The analysis is confined to cases where the lines of force and deflexion are coplanar. A. Ormerod