In the UK, the design of unreinforced masonry to resist lateral loading is carried out by yieldline analysis. It is known that this is theoretically unsound, as it assumes the existence of plastic hinges which cannot exist in a brittle material. Nevertheless, it is often claimed that yieldline theory does give reasonable predictions of the lateral strength of masonry. R. Lovegrove
The pace of change seems to be growing ever faster for the average design engineer. In the last few years, we have changed from the easily understood, if not too accurate, working stress Codes to the less familiar, if more realistic, limit state Codes. Coupled with this change, there has been a rapid increase in the volume of research work at universities and other establishments, which has been incorporated into the design methods. For many the results, in terms of practical structures, seems to have meant a great increase in the design time and little change in the final structure. A.D. Weller
A finite element method of analysis for the flexural-torsional buckling of tapered, monosymmetric beam-columns is augmented to include the effects of continuous elastic restraints. The accuracy of the finite element method is demonstrated for uniform members by a comparison with an independent, closed form solution. The application to a beam-column with diaphragm restraints is presented, and a conservative design equation is proposed. M.A. Bradford
Support ties to chimney stacks This topic, raised in our August issue, has brought a number of replies, Mr Colin Loveless disposes of the query with simple directness: The tie mentioned by ‘anon’ would be very effective in preventing the chimney from falling outwards on to the heads of passers- by below. If the wind were to blow sufficiently strongly from the other direction, the majority of the debris would presumably remain on the roof. Mr R. D. Anchor writes in similar vein, bur adds an intriguing thought: There is a simple answer: the tie prevents the stack falling onto your neighbour’s property; if it falls onto your own roof, that’s your problem. Verulam