Effect of pre- and postbuckling behaviour on load capacity of continuous beams

Abstract The nonlinear moment-curvature relationship of thin-walled beams, due to a combination of non-Hookean material behaviour and local buckling, inevitably leads to a ‘strain-softening’ component after a peak has been reached. Representation of this relationship in continuum mechanics leads to fallacious estimates of the static or incremental collapse load capacity of continuous beams. More realistic results are obtained when it is recognised that the moment-curvature relationship can only develop over a finite length associated with the half-wavelength of the final plastic buckle. It cannot develop over an infinitesimal length.