Restrained metal columns

A review of previous research into column behaviour is made. A general method of analysis for elastically restrained columns bent about one axis of symmetry and held against sway is described. The method was developed specifically for use on the English Electric 'DEUCE' computer, for which programmes have been prepared. In the method the column cross-section is considered, as a number of strips, in which the stresses are assumed to be uniform. The stress/strain curve for the column material is approximated by a series of straight lines, while proper account is taken of the unloading of fibres strained into the plastic range. The analysis considers particular columns, studying their behaviour as loading is applied up to and through collapse. The validity of the method is checked by comparisons with analytical and theoretical work by other authors, excellent agreement being obtained. Tests carried out by the author on pinned steel columns, pinned aluminium columns, and restrained aluminium columns are described. Analysis of these tests is shown to give results in good agreement with the experiments, confirming the general validity of the analysis. The results of a comprehensive series of analyses of rectangular columns of ideal elastic-plastic material are then presented. The variables considered are slenderness, degree of restraint, and magnitude and ratio of end moments. The general behaviour during loading is described. Detailed plots of collapse load values are given along with working load values calculated according to B.S. 449-1959. The load factors according to B.S. 449 are shown to be slightly below 2.0 in some cases. In most cases, however, the load factors are well above 2.0, while in some cases they are above 4.0. Finally the major conclusions of the thesis are stated and suggestions for future research given