Issue 9

Mr. Victor L. Gill (F): I would like to express my great admiration for the sheer magnitude of the work which Professor Leonhardt and Dr. Schlaich have undertaken and also the meticulous attention to detail and the engineering skill with which it has been accomplished. Briefly, there are one or two small points which I would like to make. First of all, what account has been taken of creep and relaxation in the cables? The emphasis on dimensional accuracy makes me wonder whether this may pose a problem. This is also coupled with the stress limits in the cables, but perhaps you would be good enough to comment on that point.

The paper outlines the concept initially adopted in redesigning a method of system building for large panel structures and describes tests carried out to ensure the compliance of the proposed system with the Building (Fifth Amendment) Regulations. Full scale tests to failure were carried out on vertical shear joints, horizontal flank-wall joints and individual wall and floor components. In addition, assemblies of components and joints were subjected to static internal loadings. A design approach based on observed behaviour is outlined and discussed with reference to present design requirements. V. Watson and M.J.S. Hirst

Seventeen tests on columns, supported laterally by side-rails on one flange and subjected to axial load in the presence of either uniform or linearly varying moments about the major axis have been conducted to study the behaviour of such columns in the inelastic and postbuckling range. The results have been compared with criteria which have been derived for fhe formation of plastic hinges in such columns. Michael Rex Horne and Jagdish Lal Ajmani

Programme of events

Continuous composite beams can only be designed by simple plastic theory if the hinges at the supports have adequate rotation capacity. This is often controlled by local buckling of the webs and flanges. Tests to determine the effect of local buckling on the rotation capacity of composite beams under negative bending are described, Comparisons are made with limiting web and flange slenderness ratios currently used in steel design both in Great Britain and in North America. It is found that some of the existing regulations can be applied to composite beams, but that others may be unsafe, for both steel and composite beams. Alternative rules are proposed. J. Jay Climenhaga and R. Paul Johnson

Finding the exact solution of boundary and eigenvalue problems in the case where the boundary configuration is not natural to one of the common co-ordinate systems for which the governing partial differential equation can be solved by the standard method of separation of variables is, in general, out of the question. Approximate methods such as finite differences, finite elements, collocation, etc. must be used. It has been shown by several authors that the conformal mapping technique provides a suitable approach for analysing bending, buckling and vibration problems of thin elastic plates.

Mr. Kenneth Severn, MC, MA(Cantab), CEng, FIStructE, FlCE will take office as President of the Institution on 5 October next and will deliver his Presidential Address at an Ordinary Meeting at 6 pm that evening at 11 Upper Belgrave Street, London.