Yield of a Square Reinforced Concrete Slab on Simple Supports, Allowing for Membrane Forces

Two sorts of figures, tables and references are mentioned in this text: those appearing in the original paper and those produced in the course of the discussion. The latter are distinguished by the prefix D. Mr. D.C. Teychennk: 'The few comments I will make on the paper will be restricted mainly to the material properties rather than to the structural aspects. At the Building Research Station they have agreed with many of the things, such as increased strength, which Professor Evans has claimed in his paper but the scale of increase is not the same. The increase in strength of concrete with age, depends upon many factors-the type of cement, the mix proportions, and the curing conditions.'

Two sorts of figures are referred to in this text : those appearing in the original paper and those produced in the course of the discussion. The latter are distinguished by the prefix D. Professor M. R. Horne: ‘The authors have given a clear and concise description of their method of design. They have partly achieved this by omitting all the preliminary procedures which must have been necessary, since trial and error calculations feature strongly in the method of designing the columns. The trial and error process is unavoidable in any economic, rational procedure in which elastic continuity and member stability are involved. If the whole gamut of calculations described by the authors for checking the adequacy of their sections is gone through with respect to the first choices of members, unnecessary labour is expended. As in any method of design, short cuts will soon be found after one has understood and become familiar with the steps involved. An examination of the authors’ design calculations has suggested the following approximations to be applied in a preliminary design.'

The so-called linearised deflection theory of the stiffened suspension bridge has received much attention in recent years due largely to Pugsley's work and is regarded as a satisfactory basis for predicting the behaviour of such structures. This note is concerned with the use of the principles of stationary potential energy and stationary complementary energy, respectively, for the purpose of the approximate analysis of suspension bridges by Pugsley's linear theory including the concept of coefficients of flexibility of suspension cables. The value of that concept has been supported recently by results obtained by Stephens with the aid of simple scale models. C.F.P. Bowen and T.M. Charlton