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Title: Mode interaction in lipped channel columns under concentric or eccentric loading
Author: Loughlan, J.
ISNI:       0000 0001 3612 912X
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 1979
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In this thesis an investigation into the behaviour of thin walled lipped channel columns under combined end compression and bending is reported. The thesis begins with a short introduction, followed by a review of the relevant published literature. In the introduction an outline is given of the different buckling characteristics associated with Euler, local and coupled Euler-local modes of behaviour. The scope of the literature review spans from the early development work on coupled mode buckling through to the wide variety of interaction problems covered in present day studies. An introduction to the basic differential equations and elastic strain energy expressions used in the theoretical approach of the lipped channel problem is then briefly outlined. Theoretical analyses of local instability and post-local buckling interaction behaviour are presented. The local buckling analysis is undertaken for the section using the Rayleigh-Ritz method. In this, the cross-sectional deflected shape is taken as a series of algebraic polynomials and each polynomial set in the series is arranged to satisfy all compatibility and equilibrium boundary conditions at the plate junctions and at the free edges of the lip. The analysis is carried out for various values, of section length, to obtain that value for which the lowest buckling load is induced. From this multi-term buckling analysis a very accurate approximation is used as the first term in the subsequent semi-energy post-buckling (ii) analysis, which incorporates also an additional set of algebraic polynomials to take account of changes in the deflected form in the post-buckling range. Thus, the deflection functions postulated are extremely accurate at the point of buckling and have a built-in facility to change in the post-buckling range. The numerical work involved in the analysis was carried out in the University's ICL 1904S computer for which a program was written using the FORTRAN IV programming language. Details are given of an experimental investigation which was carried out to obtain information on the interactive buckling behaviour of lipped channel columns and to provide experimental results to authenticate the validity of the theoretical solutions. A description of the loading rig and its operation is presented in conjunction with a full set of assembly and component design drawings. In general, the procedure used in the investigation was to load columns of various section dimensions and with various loading eccentricities to collapse, recording strain measurements and overall deflections as loading progressed. A strain investigation was carried out to obtain knowledge of the stress variations at the centre of the column at various stages of loading. A comparison of experimental results with theoretical predictions is given. The agreement between theory and experiment is good in general, and in particular for the comparisons of stress variations with progressive loading. A summary of the nvestigation is included, together with conclusions and suggestions for further research and extension of the analysis. The publications discussed in the literature review appear in a chronological bibliography list at the end of the text. The thesis is concluded by six short appendices which supplement the main text and enlarge on some aspects of the investigation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral