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The Structural Engineer, Volume 70, Issue 20, 1992
Dr J. B. Bellamy (F) (Marlow & Co. Ltd) The authors are ta be congratulated on a most interesting paper which shows that today, despite advances in technology, we are less willing to build large roofs in timber than our predecessors. Large numbers of Belfast truss roofs were built and appear to have given satisfactory service for many years; surely this provides us with a database of experience that could be used to assess the stress levels permitted in current Codes and the limit state factors proposed in EC5?
Mr D. J. Sharpe (F) Like Dr Brohn I worked in Hong Kong - in my case, for 10 years on the Mass Transit Railway works - and therefore was also exposed to aspects of Chinese thinking. It never occurred to me that differences between ‘western’ and ‘eastern’ thinking could be driven, or affected, by the use of a particular or predominant hemisphere of the brain. What I became aware of, however, was the basic differences between ‘western’ and Chinese thinking in a number of areas - e.g. the management style of privately-owned Hong Kong Chinese companies compared with that of countries within the Judaeo/Christian heritage. In the main, the Chinese have not been that influenced by the western mode of thinking; western Christian civilisation’s way of thinking (the ‘how’) was determined initially by the ancient Greeks, whereas ‘what’ we think was determined by Jesus Christ. As yet the opposite influence (east to west) is in its infancy.
Last words on the ‘genetic algorithm’ Last month (Verulam, 15 September) we attempted to summarise a long letter from Professor Jenkins in which he set out to expound, particularly in response to Stefan Tietz (21 July), the aims and potential achievements of his 'genetic algorith’ for structural optimisation. While we endeavoured to cover his main points, Professor Jenkins asks our indulgence in that he feeh we did not adequately present his answers to the ‘frank and uninhibited statements made by contributors’. His now proffered ‘closure’ is as follows: Mr Tietz has missed the point when he attributes functions to the GA that it does not possess. He questioned what he called ‘basic assumptions’ which did not appear in my paper. Nowhere do I talk about ‘rules’ for ‘perfection of design’ or for ‘construction costs’. I have been at pains to make the point that the GA is simply a tool in the designer’s toolkit. I am firm in my belief that structural design is an art practised by designers supported by scientific and engineering principles and methods, including computer-based methods. In this context I must urge Mr Tietz to take the opportunity to enlarge his definition of professional judgment. ‘The competent assessment of a huge number of variables’ is exactly what the GA does! Verulam