Discussion on Looking Back on 45 Years as a Structural Engineer by Fritz Leonhardt

Mr. Alan Shilston (Consulting Civil Engineer) : Insurance and the mechanism of insurance claims is a subject the consulting engineering side of the industry ought to know something about. If one tries to understand anything about insurance, it is important to find out what are the background controlling general principles and then to explore how those broad principles relate to that sector of the insurance world concerned with the construction industry. I will indicate my impressions: these should be regarded as tentative since it is far from easy to identify what broad unanimity does exist amongst insurers. I attribute this to the inherently specialized character of the various sectors within the insurance market. My contribution is confined to discussing the scope of the principles that are thought to apply. It would be helpful if the authors, supported by their colleagues in the industry this evening, could confirm or modify any of the tentative conclusions I have reached.

Towards a unified stress grading for timber It is hoped that this correspondence on the above title will cover most of the interesting points raised by Mr. J. K. Sykes (M) in the Verulam column, June 1976, page 233. Dr. D.N. Nwokoye

Professor Bolton gives an exposition of the stability of frames that may well commend itself to engineers seeking an elementary understanding of the phenomenon. Precisely for this reason it is a misleading and even potentially dangerous paper. Although far from the intention of the author, it in fact conveys the impression that frame stability is a local phenomenon, calculable from the stiffness of a single symmetrical joint in a 'no-shear' frame on the assumption that the remote ends of the columns are direction-fixed. To attempt to derive the sway stability of a frame by considering one joint is just as inadequate as the procedure common in Codes, and criticised by Bolton, of merely dealing with crudely calculated effective lengths of single members. By contrast, in discussing our approximate methods, Wood and the contributor both give explicit recognition to the fact that sway stability is an overall frame behaviour problem, thereby deriving more consistent results for derived critical loads. M.R. Horne, R.H. Wood and J.W. Bunce