Issue 6

The paper comments on the importance of the elastic critical load as a factor in structural design and deprecates unnecessary mathematical complexity. It looks forward to the end of incorrect and misleading statements which had their origin when the subject was not properly understood. The paper re-derives, in a simple way, a recent approximation for multi-storey frames, draws attention to an easy solution for some problems concerned with initial eccentricity, and discusses an alternative long- established approximation which may perhaps still be best for multi-storey frames. Correction vol 54, no 8, Aug 1976, p316 A. Bolton

The President: Thank you very much, Professor Johnson and Mr. Smith. I must say that if over 25 years ago in my drawing office days I could have knocked off a calculation like that I should have been considered a budding genius but, alas, we did not have composite beams to play with in those days.

Published below are the Institution's principal comments to the Health and Safety Commission upon the various recommendations to the Government Advisory Committee on Falsework: Final Report which was published in February last and can be obtained from HMSO, price £2 net (see The Structural Engineer, March 1976, page 86). The text of the extensive detailed comments submitted to the Commission may be obtained upon application to the Secretary at 11 Upper Belgrave Street, London SWlX 8BH; members should enclose a stamped addressed A5 envelope.

A simple hand method of calculating very good estimates of the elastic lateral buckling loads of laterally continuous beams is developed in this paper. The method uses an equivalent uniform moment concept to allow for the type of loading on the beam, and an effective length concept to allow for the interactions at the brace points between adjacent segments. Few additionalcomputations are required over and above those necessary to determine the commonly calculated lower bound estimate of the buckling load, since the additional calculations of the new method are made only for the most critical segment. Comparisons of the predictions of the proposed method and of the lower bound method with the accurate finite element results show that the proposed method consistently leads to far more accurate predictions. D.A. Nethercot and N.S. Trahair

The paper discusses the interpretation of the results of static penetration tests in terms of the geological structure and traditional theory together with the evaluation of the ultimate base and shaft resistances of driven piles from measured cone resistances. S. Thorburn

The subject of responsibility for and the checking of designs continues to draw comment. In earlier columns we asked to hear of their experience from engineers in commercial firms and also from consulting engineers who check submitted designs on behalf of authorities. As a chartered engineer working in the former situation Mr. M. T. Ely writes: I do not wish to enter into the arguments regarding responsibility and liability in the preparation and checking of designs and calculations; suffice to say that as a chartered engineer, working for a commercial firm, I consider myself responsible for my own designs. Heaven forbid the day should come when a checking engineer insists on a change in my design or calculations which I consider to be unnecessary or downright wrong simply to satisfy his own ideas! Verulam