Elastic buckling of latticed and thin walled columns. Studies in overall and component stability

Kenedi, Robert M (1949) Elastic buckling of latticed and thin walled columns. Studies in overall and component stability. PhD thesis, University of Glasgow.

Abstract

Columns in general can be regarded as built up of components. These components may be of different structural form, such as the column legs and the latticing of a Latticed Column, or may be of the same form, such as the flange and web plates of a Thin Walled Column. In any one case failure may occur either by integral column action - "Overall Instability" or by failure of one of the components - "Component Instability". The contents of the thesis are divided into two main parts. Part I presents a review of published Analytical and Experimental Investigations of Latticed Columns, followed by a short critical discussion. This reveals, on the experimental side, the lack of complete column distortion data and on the theoretical side, the absence of stability analysis of the column leg components as distinct from the panel elements. The review is followed by the presentation of the experimental work carried out on a model latticed column, from which the complete distortion of the column legs were obtained by measurement of the lateral deflections at 18 points along their length. Using the experimental work as a guide an analysis is developed, which gives the buckling load of Latticed Columns based on the stability of the column legs. Account is taken of the action of lateral loads' on the column legs, the magnitude of these loads being dependent on the elasticity of the latticing. In its application, the critical stress given by this treatment is taken as the "ideal column" buckling stress of the Perry-Robertson formula, which is then utilised to complete actual failure stresses. Values calculated in this manner are compared with the published experimental results of other Investigators. Part II gives a brief survey of the relevant published theories of flexural and torsional integral column stability, and flexural plate stability under compressive actions. The thesis then presents the experimental work carried out on thin walled columns consisting of some 70 tests to destruction of 3 ft. long channel section specimens. The tests were designed to cover the complete range of integral column and plate component failure. Special study was made of the conditions obtaining under simultaneous overall column and plate component collapse. The characteristics of flange plate failure were further investigated on two 12 ft. long channel section columns tested to destruction. Complete edge deflection data for the flanges together with a stress survey of the flange surface are presented. The experimental buckling stress results of the plate failure range, are analysed on the basis of the classic plate buckling theory, leading to the evaluation of the degree of edge fixity of the flange plates. This is followed by a comparison of the experimental results with calculated distributions given by the Perry-Robertson formula - the plate critical stress being taken as the "ideal column" buckling stress and by the present day stress basis of American design. The findings of the investigations presented in the thesis fall into two categories, namely (i) Specific characteristics - appertaining to details of theoretical and experimental behaviour. These are given in the Summaries at the end of each section. (ii) General features appertaining to a substantiation of the Perry Robertson formula, while developed originally for the "Overall" type of failure it is shown to be applicable to the "Component" failure range also provided the values of the imperfection factor and the "ideal column" buckling stress correspond to the characteristics of the weakest column component.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: William Kerr
• Keywords: Civil engineering
• Date of Award: 1949
• Depositing User: Enlighten Team
• Unique ID: glathesis:1949-72721
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Jun 2019 11:06
• Last Modified: 11 Jun 2019 11:06
• URI: https://theses.gla.ac.uk/id/eprint/72721