Issue 3

The behaviour of framed tube structures is discussed from an overall structural system point of view. The influence of various structural parameters is emphasized for achieving better tubular behaviour. The concept of the equivalent reduced plane frame modelling technique is used for developing a series of 'influence' curves for the preliminary analysis and design. An example problem is worked out using these curves and the results are compared with a more exact solution by the computer. Fazlur R. Khan and Navinchandra R. Amin

Dr. W. W. Chan (F): I am privileged to be given the first opportunity of congratulating you and your associated companies for the efforts and costs which have been given to further the understanding of the resistance of large-panel structures to progressive collapse. The experiments have demonstrated the importance of mechanical steel connections and the importance of limiting the stagger at overlapping in order to develop the full strength in tension of the looped connections. Both of these factors were arrived at by, albeit intuition, when we first contrived Circular 62/68. The great controversy at the time was the shear friction resistance and the sliding of the wall connections which it was always recognized was real and present under loading. But, at that time and I believe still now, we are unable to relate the results of static experiments to their dynamic equivalent. Mr. Watson and I have in the past, for some polite reason, avoided the word ‘explosion’.

Matrix methods are available to analyse structures of any shape. However, when designing a structure, it is often necessary to find out, without further tedious analyses, exactly how the forces and the deflexions throughout the structure change when some or many of its members are either varied or totally removed. K.I. Majid and D.W.C. Elliott

President’s Diary The President and Mrs. Kenneth Severn look forward to joining members and their ladies of the Bedfordshire and Adjoining Counties Section at their Annual Dinner and Dance in Bedford on 2 March; Mr. Severn, accompanied by the Secretary, will travel to Belfast for the Annual Dinner of the Northern Ireland Branch on Tuesday 6 March, and on Friday 9 March the President will be with members of the Teesside centre of the Northern Counties Branch at their Annual Dinner.

This paper deals with an investigation into the behaviour of an unreinforced throated section of different proportions in an axially loaded concrete column. D.H. Wade