Professor W. M. Jenkins (F)(Hatfield Polytechnic) Dr. Cunningham’s paper is a welcome contribution to the growing body of knowledge of ‘semi-rigid’ connections, particularly since he has directed his studies to the implications for design of such connections. The important practical aspects of connection behaviour have been correctly identified in the paper and are (l) non-linear moment-rotation characteristics with the connection stiffness reducing as applied moment increases; (2) considerable ductility and, with satisfactory design, consequent rotation capacity at ultimate conditions; (3) a complex interaction of the design variables and consequent difficulty in predicting strength and (particularly) stiffness.
David Lazenby will succeed James Armstrong as President of the Institution 1990-91 at an Ordinary Meeting at Institution headquarters on 4 October. The handover ceremony begins at 6pm, when Mr Lazenby will deliver his Presidential Address ‘Whose Institution is it, anyway?’, the full text of which will be published in The Structural Engineer in November.
U-frames are an available option used to brace the compression flanges of beams used in deck-type composite bridge decks and in halfthrough bridges. E. Jeffers
The use of centrifuges to improve similarity in geotechnical model studies has developed rapidly over 2 decades, in the UK and elsewhere. With increased numbers of machines of varying size, power and sophistication, the opportunities for engineers in practice to avail themselves of this technology are increasing. A review is presented of what has been achieved to date, and some conclusions are drawn. A new era of model testing, with the inclusion of greater precision in simultaneously modelling above- and below-ground components of complex structures, is foreseen, for both static and dynamic situations. W.H. Craig
Potential for catastrophe in building alterations Mr P. S. Rhodes of Bangor, Northern Ireland, relates our correspondence on this topic (raised by Peter Mawer on 20 March, with subsequent contributions in our columns for 15 May and 19 June) to a previous article under his own authorship: I refer to The Structural Engineer of September 1974 (Vol. 52, No. 9), p332, the top four paras on the second column, and also to p333, second column and ‘Lessons for the future’. Verulam