This paper describes the design and construction of a new floor within an existing telephone exchange. D. Vesey
Mr President, my lords, ladies and gentlemen, it is a great personal pleasure and privilege to be accorded the task this evening of proposing the first toast. As you will see from the official menu card, it is one of those toasts that speaks for itself. It is to the Institution, and that is surely as it should be. However, when I think of the wording and substance of the toast, it is for me, and I know for many of you, something much more than an institution. We honour, in the toast, two generations and two groups those who, down the years, have found it to be to their advantage professionally (to their professional calling and to the work that they have done in society) that there should be an Institution, and those who share common aims, responsibilities and tasks, be it as engineers, architects or as of that myriad of professions which go to make up the collegiality of the practice of which you are justly proud in cement, glass, plastic, and other things. (I hope that those of you who are in your inner councils will recognise what I meant by that last remark.) Dr. Robert Eames
The problem Claims for extension of time and for additional loss and expense due to disruption of work on site have become a pervasive feature of life in the construction industry since the war. More recently, there have been very significant increases in the insurance premiums paid by professional offices for professional indemnity insurance. D. Azzaro
Dr. F. G. Buffler: Dr. Hobbs’ views differ in a number of respects from those given in the draft Concrete Society Technical Report Minimising the risk of alkali-silica reaction-Guidance notes and model specification clauses which was issued in 1985 and resulted from the deliberations of a working party under the chairmanship of Mr M. R. Hawkins. The edited version of this report should be published in 1987. Dr. Hobbs has, on more than one occasion, attended meetings of the working party in order to present his views, particularly with respect to the maximum alkali limit for concrete and on the effectiveness of pulverised-fuel ash (pfa) and ground granulated blast furnace slag (ggbfs) as means of minimising the risk of the occurrence of damaging expansion due to the alkali-silica reaction. On those occasion his views were similar to those stated in the present paper but, for a variety of reasons, the working party decided not to adopt them. It must be emphasised that the opinions given below are personal ones and that, although other members of the working party might agree with them, there has been no meeting of the group to comment on the technical differences between Dr. Hobbs’ paper and the revised version of the draft Concrete Society report referred to above.
1. Policy objectives (a) to retain the consumer’s freedom of choice through the preparation of voluntary standards endorsed by consensus; (b) to derive, through collaboration on the European or world level, British Standards that will help to sell UK products and services overseas; (c) within agreed criteria, to write performance-based standards that will not inhibit manufacturing innovation or trading competitiveness; (d) to pursue a planned approach to European standardisation, including proper justification of projects harmonisation is not an end in itself-and provision for suitable transitional arrangements for implementing European standards systematically at the national level; (e) to identify and promote appropriate British Standards for adoption as international and European standards and for endorsement as meeting essential requirements laid down in EC directives; (Q to promote mutual recognition within Europe of testing, inspection and certification bodies on the basis of harmonisation of their operating procedures and acceptance criteria. R. Harrison
Mr C. J. Judge (G) (Building Research Establishment): I would first like to congratulate all those concerned with the structure described in this paper for allowing the details of the failure to be published. It is only by publishing details of failures that other engineers can learn about the limitations in structural design.
I am indebted to the engineers who have responded to my views, and I do not wish to take issue with any contra views; we all have our own perspectives on important matters. David Wardle
A steady rise in groundwater levels in the aquifer beneath London was noted as long ago as 1972, but only recently has attention been focused on the potential engineering implications of this rise. Sponsored by the Department of the Environment and other interested parties, the Construction Industry Research & Information Association (CIRIA) has organised a study into the problem. This paper describes some of the effects which a rise in groundwater levels might have on structures and is based on work currently being carried out under contract for CIRIA. T. Blower
Tensile stresses in concrete Mr J, T. Chase of Worcester continues our correspondence, following Mr Pannell’s letter in July 1986, on the queried justification for reliance on tensile stresses in design in unreinforced concrete. Mr Pannell referred to the subject specifically in relation to the use of minipiles to strengthen ground slabs where settlement has occurred. Mr Chase believes that there is no need in such cases to appeal to tensile strength, since in practice arching action offers support. He writes: In the particular case of minipiles supporting a plain concrete slab on a grid of 1.0-1.5 m in dwellings, I believe the slab is supported by arching action within its thickness. In practice, the slab acts as a series of mutually supporting domes until an edge is reached, tensile strength playing no essential role except, perhaps, at the slab edges. At the edge, restraint is provided by: (i) the piles themselves reacting against the fill above the footing and in bending; (ii) the surrounding brickwork, supported in its turn by the external ground; (iii) the stiffness provided by the edge strip of the slab between the last row of piles and the wall: here the slab is acting as a deep beam spanning horizontally between piles. Verulam Verulam