Buckling of real structural elements II


To extend and generalise to other instability phenomena the conclusions drawn in Buckling of Real Structural Elements I  lecture on column buckling.


Plate buckling and types of buckling involving torsional deformation are considered, as is the basic type of shell buckling, i.e. the case of an axially compressed cylinder. For each type of buckling, a description of the basic phenomena is given. The behaviour is analysed in terms of the pre-buckling, post-buckling, and collapse behaviour, and the governing geometric parameters are identified. Comment is also briefly made on how members can be strengthened to prevent buckling failures.


The influence of imperfections, material plasticity, and strain hardening on ultimate resistance have been reviewed in detail in the Buckling of Real Structural Elements I lecture with reference to column flexural buckling. This is the form of member instability that has been most studied and an almost complete understanding of the phenomenon has been achieved.

Most of the conclusions drawn in the previous lecture are still valid, in general terms, for other forms of instability. These forms are, however, characterised by different kinds of deformations so that the nature of the imperfections that most affect the ultimate resistance are different to flexural buckling. To gain an understanding of the real buckling resistance of columns, therefore, the effect of imperfections on these different forms of instability must be analysed.

Plate buckling is first examined because it often occurs in the form of local buckling, i.e. buckling of section-plate components; moreover, it helps to understand torsional column buckling, where buckling occurs with a twist of the cross-section only. Column flexural-torsional buckling is then examined. This is well named because bending and torsional deformations are always linked together as in the lateral-torsional buckling of beams. Buckling of shells is also considered; this very complex phenomenon is illustrated by reference to the basic case of an axially loaded cylindrical shell.

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