Author: Liddell, W I
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Liddell, W I
The Structural Engineer, Volume 71, Issue 14, 1993
Code limits on deflections On 17 November last year, Dr J. B. Bellamy invited information concerning the origin of the deflection limits set out in the various structural Codes. He responds to comments that have appeared in Verulam from Roger Mead and Mr C. K. Lim: I would like to thank Mr Lim (20 April) for his quotation from Structural engineering by White, Gergely & Sexsmith which justifies the limit as a device to prevent tension craclung of plaster. Mr Lim does not give the date the book was published, but the reference to plaster rather than plasterboard suggests a date prior to World War 2, and that could explain the thinking behind the wording of current British Codes. More recent thinking would surely consider it more appropriate to control the tensile stresses in the plaster, not the deflection of that member. On that basis, the deflection clauses in many Codes are now archaic and need overhaul. Verulam
The behaviour of purlins subject to wind uplift has never addressed in British Standards or Codes of Practice but, completion of EC3, design rules are now available. This assesses the competitiveness of such methods when compared the traditional 'design by testing' approach, and illustrates this new 'state-of-the-art' design method appears to be conservative by about 30%. P. Leach and P. Robinson
An all-steel sandwich punel consists of two steel facing flat plates spot-welded onto a core of stiffeners, which may consist of zed sections, tophats, channels, or corrugated sheeting. Such panels have been studied extensively, and both numerical and analytical comparisons have been reported. This paper presents a modified thick plate approach for the analysis of snndwich panels. To better appreciate the development of the proposed method, a brief review of the previous modelling techniques - i.e. closed-form solution, grillage analogy and the conventional finite element modelling - is given. K.H. Tan, T.C. Fung and T.S. Lok