The Rankine-Merchant Load and its Application
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Relationships between the elastic critical loads, non-linear elastic load-deflection behaviour, rigid-plastic behaviour and elastic-plastic failure loads of frame structures are discussed. The concept of deteriorated critical loads is explained, and its value in obtaining an understanding of the criteria for failure of structures in the elastic-plastic range demonstrated by reference to examples. The use in the Rankine-Merchant formula of the two idealised load factors for elastic buckling and rigid-plastic collapse to obtain an approximation to the true elastic failure load is explained, and it is shown what idealisations have to be made to arrive at a formal proof. This enables conclusions to be reached over the situations in which the Rankine-Merchant load tends to give either a high or a low estimate of the true failure load. Correlations between the Rankine-Merchant loads and the true collapse loads obtained in both theoretical and experimental investigations are presented. Finally proposals are made to enable the Rankine-Merchant load, either in its original or in a modified form, to be used reliably for design purposes.
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- 1.Home M R, “Fundamental propositions in the plastic theory of structures”, J Inst Civ Engrs, vol 34 1949, p174Google Scholar
- 2.Greenberg H J and Prager W, “On limit design of beams and frames”, Trans Amer Soc Civ Engrs, vol 117 1952, p447Google Scholar
- 3.Baker J F, Home M R and Heyman J, “The Steel Skeleton vol 2”, CUP 1956Google Scholar
- 6.Home M R and Morris J, Plastic Design of Low-rise Frames, Granada 1981Google Scholar
- 7.Home M R, Plastic Theory of Structures, Permagon 1979Google Scholar
- 8.Merchant W, Rashid C A, Bolton A and Salem A, “The behaviour of unclad frames”, Proc 50th Anniv Conf, Inst Struct Engrs, 1958Google Scholar
- 10.Murray N W, “The determination of the collapse loads of rigidly jointed frameworks with members in which axial forces are large”, Proc Inst Civ Engrs Part III, vol 5 1956, p213Google Scholar
- 12.Salem A, Structural Frameworks, PhD Thesis, Univ Manchester 1958Google Scholar
- 15.Wood R H, “Effective lengths of columns in multi-storey buildings”, Structural Engineer, vol 52 1974, pp235, 295 & 341Google Scholar
- 16.Home M R, “An approximate method for calculating the elastic critical loads of multi-storey plane frames”, Structural Engineer, vol 53 1975, p242Google Scholar