Workmanship fpr a Structural Concrete Code. Discussion on the paper by T. N. W. Akroyd MSc LLB CEng

Mr. A.R. Kjar (Research Student, University of Tasmania) writes: ' In part 2 the authors have presented results of tests on I-beams and concrete columns lifted by cables. A straight Southwell plot on rotation against load was used in an effort to correlate the behaviour of the physical and mathematical models, in the hope of justifying the mathematical model. '

A numerical procedure based on the successive approximate method is used for the determination of elastic buckling loads of columns. For the two cases, (l) columns hinged at ends, and having a symmetrical variation of moment of inertia (if section varies); and (2) columns with constant or varying section, fixed at one end and free at the other; it is shown that the major calculation involved in the method, which is the determination of deflections, can be easily and mechanically done. Thus the determination of elastic critical load for such columns becomes very easy and is illustrated in four worked examples. Prakash Desayi

This month's letters cover legislation for design checks, embodied carbon of modular construction approaches, and assessment of masonry buildings for earthquake resilience in New Zealand.