Issue 9

1. The Panel is extremely conscious of the ongoing nature of the work necessary to put limit-state design using partial safety factors on a consistent and logical basis and of the amount of research that will be required to provide a sound basis for this. This second report is directed at offering some general recommendations to Code drafting committees when dealing with partial safety factors, suggest in guidelines for the experimental calibration of these on the lines of the suggestions made in paragraphs 4, 5, 6 and 7 of the first report*, and indicating subjects where further study and research is desirable.

Dr. Gunaratnam has undertaken a useful service for designers in comparing curvature and deflection calculated according to CP 110 Appendix A with the values obtained by simpler methods. However, his statement that the latter ‘lead to an underestimation of the curvature in all cases’ is startling for, if I have understood him correctly, he is saying that, by taking account of the stiffening effect of the concrete in tension, the calculated curvature is actually increased ! E.W. Bennett

This paper outlines some of the basic steps taken and factors to be considered in the design of lattice steel towers. The TOWER computer system is described. This is an interactive computer system comprising three programs developed especially for the structural analysis, design, and automatic drawing of self-supporting lattice steel towers. Details are given of the scope of the computer system and of its method of operation as an interactive design aid. The designer can take advantage of a wide range of available program options to define the structural system, the environmental loadings, and the strength and serviceability design criteria. The benefits of the computer system include considerable savings in overall design time and improvements in the accuracy of applied loadings and member forces for design. Michael Shears and Graham A.N. Thomas

Dr. J. M. Lovegrove: I should like to describe some work that is at present being carried out in the Civil Engineering Department of all of Southampton University. The work is supported by grants totalling £60 000 from the Science Research Council, extending over 5 years from September 1976.

This paper introduces a computer system devised to assist the steel fabricator through the various stages of a steelwork contract. Working documents for estimating, material ordering, fabrication, and erection are produced. The system can handle beam and column buildings of irregular layout and size, and has been fully operational for some time. The volume of work being processed is currently at an average rate of 10 000 t/annum. E.F. Boyle

There has been an increasing interest in the past decade in the use of computers for the design of structures. The rapid increase in computer technology has encouraged this interest and provided a stimulus for the development of programs that can be made available on the engineer3 desk. This paper presents a review of the current position from the point of view of the engineer seeking to gain information. It indicates the limitations of computer applications, gives some guidance on the types of program available, and considers possible future developments. A. Weller

A review of computer systems philosophy is presented. The effect of this philosophy on software development is examined. A typical suite of interactive programs for the plastic design of multibay portal frames in steel, PORTAL is described in detail. A short design study is included that highlights the effect on costs of varying the number of portal frames of a typical building. R.E. Yeadon

John Derrington, BSc(Eng), DIC, FEng. FIStructE, FICE, FCIArb, succeeds Professor A. J. Harris as President of the Institution on 4 October next, and will give his Presidential Address 'The contractor's place' at an Ordinary Meeting 6.0 pm that evening at 11 Upper Belgrave St., London SWlX 8BH.

The preparation of the revised design rules for steel bridges is now in its final stages. The new standard incorporates the fruits of the research that has taken place since the establishment of the Merrison Committee some 7 years ago. J.E. Harding and R.E. Hobbs

Insurance and underpinning Both Mr. Bratchell and Mr. A. J. 0. Russell have expressed views on this issue, first raised by Mr. Collett (January 1979) and commented on by Mr. Park (May l979). From Mr. Bratchell: I suggest that the question of insurance of house foundations should be related to a reasonable expectation of life of the building. If a domestic house is expected to be designed and built for a life of, say, 50 years, one can hardly claim for foundation renewal at, say, 60 years. It ought to be possible to lay down guidelines which take account of expected life, and thus to allocate costs between repair and betterment. In my view, the need for underpinning should be covered by insurance only if it relates to a cause other than deterioration from age. Verulam