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The Structural Engineer, Volume 67, Issue 23, 1989
Robert Tristram (G) writes: Some very interesting points have been raised by Dennis Waite and Donald Evans (5 September and 3 October). Few would disagree with the statement to the effect that Codes should be written for the acceptance of fools and the guidance of wise men. Also, it does seem that a great deal of innovative design is stifled by unimaginative and defensive approving authorities: the idea that an approving engineer might be of an altogether lower level of proficiency than the designer does give some cause for concern.
Mr A. C. G. Hayward (F) (Cass Hayward & Partners): The new national steelwork document should be welcomed by most engineers in that they need expend less effort in writing a specification for what is a specialised product. Provided that the document is widely adopted, employers should benefit long term from more uniform pricing of steel fabrication, and it appears to be gaining acceptance. A unique specification always attracts higher rates, because of either lack of familiarity or the need for the fabricator to institute procedures (such as machine ending) extra to his normal production line.
The stability of a beam may be seriously reduced when the beam is supported on seat supports that prevent only the tension flange from deflecting laterally. The buckling mode will then be distortional, with local web distortions at the supports increasing the lateral deflections during buckling. An elastic finite element analysis of distortional buckling is verified in the paper against experimental results for partial end restraint. The elastic analysis is then used to evaluate the critical load of a beam on a seat support under moment gradient. An inelastic extrapolation of the distortional buckling analysis is compared with test results on hot-rolled beams and is then used to study the relationship between the slenderness and inelastic buckling strength of a beam with a seat support. M.A. Bradford