Issue 3

The paper presents a simple design aid for predicting long-term movements up to 50 years in buildings and bridges made of normal and lightweight aggregate concrete. The method is based on the principle of superposition and a creep factor chart which takes into account varying sizes of members, age at loading, exposure conditions, and percentage of reinforcement; it requires only a knowledge of the 28-day cube strength and the loading history of the member. The method is developed from a study of in situ movements in two reinforced concrete structures subjected to incremental loading. The predicted load-induced and basic (i.e. elastic + shrinkage + creep) strains show excellent agreement with the measured strains in the two structures with an error coefficient within 11% at all ages. The method is shown to give good agreement with measured strains on normal weight and lightweight aggregate concrete columns reported from America, and on the Medway Bridge. R.N. Swamy and P. Arumugasaamy

Professor F. W. Williams (M) and Dr. J. R. Banerjee (Department of Civil Engineering and Building Technology, UWIST, Cardiff): It is vital that designers should be aware that the author’s method gives only some of the natural frequencies of structures, and that the second and other low natural frequencies are likely to be among those missed. This is illustrated by considering the rectangular grid of Fig 13, which consists of 1250 identical, rigidly jointed, inextensible members and is prevented from swaying.

Mr W. J. Searle (HM Inspectorate of Mines and Quarries): I should like to congratulate Mr Taylor on his comprehensive review of colliery surface structures and the problems associated with them.

President’s diary The President and Mrs Horne look forward to meeting members of the Bedfordshire and Adjoining Counties Branch at their Annual Dinner in Bedford on Friday 6 March. Professor Horne will be visiting Belfast on Tuesday 10 March and will be responding to the toast to the Institution at the Branch Annual Dinner that evening.

Finniston Report: proposed Engineering Authority The Department of Industry in mid-January, contrary to expectations, circulated to the CEI and its constituent chartered engineering Institutions a revised draft Charter which, it was suggested, would bring into existence the proposed Engineering Authority. In response to informal comments on that draft, a second was circulated a week later. The Presidents of the 16 constituent Institutions, with the Chairman of the CEI, met together, and the following letter was sent to Sir Keith Joseph, Secretary of State for Industry, on 28 January: ‘We, the Corporation Presidents and the Chairman of the CEI, whose signatures are appended, feel once again bound to represent to you personally our disquiet at the manner in which discussions of the Royal Charter for the new Engineering Council have developed.

The paper emphasises the importance of the stress histories of cohesive soils, particularly in relation to the prediction of settlements of building structures. A method of recognising and assessing the overconsolidation icepressure from static cone penetration tests is introduced, together with cone factors related to overconsolidation pressures. S. Thorburn, C.L. Laird and W.M. Reid

Building Regulations fees When money is involved, argument always ensues, so the question of these fees, of course, produces some argument. A correspondent, who wishes to remain anonymous, suggests an equitable evaluation method: During the past year, since the Government instituted fees for Building Regulations approvals and inspections, the local authorities have necessarily had to set up administrative arrangements for their assessment and collection. The fees are related to the value of those parts of the work subject to the Regulations according to a scale. I uncierstand that considerable unproductive-and frequently abrasive-correspondence and negotiations are devoted to agreeing the value of the work. What a waste of effort! Why cannot the fees be related directly to the floor (and roof) area of the building and be updated yearly, or whenever, in accordance with the retail price index? I suppose they’d argue about the area then, though . . . . Verulam