On the analysis of viscoplastic buckling

For elastic-viscoplastic structures the classical elastic-plastic bifurcation approach to inelastic buckling is not valid. Only an elastic bifurcation point exists in the el~tic-viscoplastic case, and the inelastic buckling behaviour is controlled by a strong sensitivity to small imperfections. However, in the last few years some papers have been published on an approximation that leads to a so-called viscoplastic bifurcation point. Results of accurate numerical analyses for elasticviscoplastic columns are compared with predictions based on the approximate bifurcation approach. In some cases the bifurcation approach gives a poor approximation of the actual elasticeviscoplastic column behaviour, whereas in other cases the discrepancy is less pronounced. The simple column model gives a clear illustration of the effect, but similar results for plates are also mentioned briefly.