Advanced Steel Construction

Vol. 1, No. 1, pp.47-66 (2005)



Y.L. Pi1, M.A. Bradford and Y.Y. Chen

1The corresponding author, Senior Research Fellow, School of Civil and Environmental Engineering,

NSW, Sydney, NSW 2052, Australia.

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When an arch is subjected to in-plane loading, it may suddenly deflect laterally and twist out of the plane of loading and fail in a flexural-torsional buckling mode. This paper presents a static equilibrium approach for theelastic flexural-torsional buckling of circular arches under uniform bending, or under uniform compression. Solutionsfor the buckling moment and buckling load are obtained in closed form, and discrepancies among existing solutionsare clarified. It is found that it is reasonable to use material curvatures and twist, rather than spatial curvatures andtwist, for the flexural-torsional buckling analysis of arches. First order buckling deformations provide a sufficientbasis for the static equilibrium methods for the flexural-torsional buckling analysis of arches. Equilibrium of alengthwise differential element of an arch should be considered in the analysis, and so the couplings between thelateral bending and torsional actions and resistances can be included in the differential equations of equilibrium. If theequilibrium is considered only at the cross-section, this is equivalent to treating arches as analogous with straightmembers, and so the coupling terms in the differential equations of equilibrium are lost.


Keywords:Arch, Bending, Buckling, Compression, Elastic, Equilibrium Approach, Flexural-Torsional


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