Mr. S. Butler: ‘Having read the paper before I came to this meeting, and from past acquaintance with the aeroplane, I should first like to make a statement and then put a question. I was interested in the mention of seven per cent of take-off weight for the pay load; in fact in the paper it says “Only seven per cent”. This was rather more creditable than one tends to think. For a railway train, thought of as a transport vehicle, I believe it is one per cent, if not appreciably less. I think the optimum in percentage pay load goes to a mini car with four hefty men and luggage, and that makes about thirty to thirty-five per cent.'
A new general method is presented for analysing the distribution of concentrated loads in right orthotropic bridge decks. The analysis is compared with the Guyon-Massonnet analysis within the limited range of the latter and is found to give significantly higher values of longitudinal moment. Good correlation is found with experimental values on slabs obtained by Rowe and by the authors. Professor A.R. Cusens and R.P. Pama
The Institution is concerned that the evidence to the Griffiths Tribunal on the subject of gas explosions, etc., has been taken so literally and used as a basis for the amendation of the Building Regulations. It is of the opinion that, in general, multi-storey framed buildings should be properly designed and constructed in accordance with current Building Regulations and the relevant Codes of Practice should be able to accommodate the sort of ‘unpredictable additional loads and effects’ which are presently envisaged but which are not as yet quantified or statistically substantiated as a real risk.
The results of push-out tests on 8 mm (5/16 in) diameter studset in reinforced concrete slabs in tension are presented and discussed. Examination of the applicability of the conclusions to larger studs and to studs in beams is followed by design recommendations for connectors in hogging moment regions of continuous composite beams. Encased beams and haunched beams are not considered. R. Paul Johnson, R.D. Greenwood and K. Van Dalen
It is shown that an examination of the deformation of a free cable suggests an array of diagonal stays or braces as a means of reducing the deflections. The braces prestress the cable which, since it behaves nonlinearly, produces an increase in the stiffness. Bracing is similar to gravity loading in that it increases the vertical forces acting on the cable. The increased stiffness is thus analogous to gravity stiffness. A theory is presented for analysing this type of structure, and a numerical method of solving the governing equations is given. An experimental investigation verifying the theory is included and finally a theoretical discussion of the significance of the main parameters is given. T.J. Poskitt and P.R. Stott
Mr. F. C. Greenfield : ‘The design-or examination of another’s design - of a modern structure calls for “professional excellence” comparable with any other of man’s skills; it is high time the layman was aware of this. Legislation is badly needed to ensure that the public are protected through structural design, examination of structural design (on behalf of the local authority) and also supervision on site-all under the direction of Chartered Engineers recognised in their profession for their skill in this field. Local authorities should ascertain that they have the necessary professional excellence in their staff; if they do not they should either attract the right men or engage Consulting Engineers-or do both. For those who rely entirely on their own staff, full responsibility must be shouldered by the engineer-Chief Officer.'
Mr. M. H. Rees: 'This is an extremely interesting structure and I have really just three questions out of the very numerous thoughts that have occurred to me, mostly concerned with the staging of prestressing and the adjustment of arch thrust on decentering. Both of these go to make tools invaluable to the designer in making large span concrete structures economic.'
Mr. C. B. Stone, DSO, BSc(Eng), FICE, will take office as President of the Institution 1969-70 on 2 October next and will give his Presidential Address at a meeting at 6 pm that evening at l1 Upper Belgrave Street, London SWI.