Issue 16

The capacity design procedure used in New Zealand for the design of multistorey RC frames and walls of buildings for resistance against severe earthquakes is described. The aim of the capacity design procedure is to ensure that the members and joints of structures have appropriate levels of strength in flexure, shear and bond, so that appropriate detailing of longitudinal and transverse reinforcement will lead to structures with sufficient ductility in a flexural yielding mode to survive severe earthquakes. Developments in New Zealand in capacity design provisions, and in the understanding of the behaviour of reinforced concrete beams, columns, beam-column joints and structural walls during severe earthquakes, are discussed. Comparisons are made of the seismic design provisions for reinforced concrete structures recommended by New Zealand Codes and by draft Eurocode 8 for the design of building structures in seismic regions. Professor R. Park

Mr J. G. Roddick (M) (formerly W. S. Atkins) Mr Cole’s article provides a most useful legal background to this subject but, in my opinion, it also identifies an ethical issue which is of fundamental importance to members of the Institution. It contrasts the expert witness’s appointment by one of the parties to a dispute with the expert’s duty to the court to be scrupulously impartial.

Attempting a summary of the application of computers in structural engineering is a little like taking a photograph of a river; when the prints come back, they may tell you that it is water, but the most important bits of information are absent - the rate of flow and what the river carries upstream. D.M. Brohn

Papers - too ‘academic’? Mr W. E. A. Skinner’s letter (21 April), which initiated this topic, was in reaction to a paper (‘Structural optimisation with the genetic algorithm 7 by Professor Jenkins, who himself responded on 16 June. In a further letter Mr Skinner, after remarking that the response he had had in mind has been covered pretty well by Stefan Tietz (21 July), continues as follows: As Verulam rightly points out, Stefan Tietz has made some interesting points which will no doubt provoke further discussion. It seems to me that, underlying this whole question, is the matter of the distinction between the arts and the sciences as applied to the practice of engineering. I have always felt that structural engineering was much more of an art than a science and that, in the creation of any structure, the correct concept was a much more important factor than the detailed design of the various elements that comprise the whole. In recent years, we have distinguished between ‘technicians’ and ‘engineers’ - presumably, the latter are those who can do the creative bit and the former the ones who do the sums. The advent of computer aided design has probably done much to emphasise this differentiation, and a great deal of space in the Journal is taken up with papers dealing with detail design and - probably for the reasons given by Stefan Tietz - not enough to the discussion of conceptual thought. I can remember the time when consulting engineers concerned themselves only with advice on concept and consideration of particular problems in design of foundations and other tricky items - detail design was done by the contractors. Perhaps, with the advent of the ‘design and build’ concept, we are returning to that system and maybe the consulting engineering profession will stop employing large numbers of staff preparing details and schedules! Verulam