The Scientific and Practical Training of the Structural Engineer

BEFORE the year 1900 many skyscrapers had been erected in the United States of America and steel-frame buildings were quite usual there. Cast-iron bases and columns were much in use, while buildings of thirty storeys were considered high. S. Bylander

Soil mechanics or, in other words, the science of soil action, is now receiving a considerable amount of publicity from civil engineering journals; in fact, scarcely a week passes without some reference being made to the subject in those of American and Continental origin. Judging from the accounts given, there can be little doubt that this subject has, certainly in some countries, become the leading topic of interest among all those concerned with, and responsible for the safety of foundations, and has evidently so far advanced as to be considered of practical utility. The widespread interest taken in the development and progress of the subject, was further manifested by the enthusiasm which marked the inauguration of the First International Conference of Soil Mechanics and Foundation Engineering at Harvard University last June. During the sessions Reports were presented from all over the world, these displaying remarkable activity in certain quarters to place the new science on a practical footing. M.J.C. McCarthy

Sir,-It is noted that the author of the article on “Recent Progress in Bridge Design in Tanganyika Territory" admits the accuracy of the deductions concerning the stresses in the structure referred to in my letter published in the September issue of your Journal. I have read again with care the original article, and can see no reference whatsoever to the decking slab being cast some considerable time after the webs of the beams. If this procedure to be followed it is hard to understand the reference to a factor of the safety in the Rolled Steel Joists of 3 due to dead load, if the bridge is to be constructed in such a fashion that this loading cannot come on the naked steel joists. Whether the design is such that the slab may be considered adequately bonded to the web of the tee beam is open to serious question, and most designers in structures of this type place the top flange of the R.S.J. just under the top surface of the slab. (Water & Water Engineering, Midsummer, 1932, page 260, etc.) The use of comparatively heavy and unwieldy R.S.J.'S under the conditions visualised in the paper would hardly appear to be justified as a normally designed reinforced concrete beam would contain much less steel and would only necessitate vertical strutting. Such reinforced concrete beam bridges for similar spans have been constructed in numerous cases during the past 20 years by the South African P.W.D. utilising native labour.