Optimum Design of Columns Involving Plastic Buckling

抄録

In practical design of columns, the estimation of the plastic buckling strength is important in view of reducing the structural weight or the cost of material. In this paper, the problem of maximizing the plastic buckling load of a column of given volume, length, and material is studied. The finite element method based on the incremental theory is used to determine the ultimate strength of eccentrically loaded columns. the shape of columns, i.e. arbitrary distribution of the cross sectional areas of columns along their length, is postulated to be an exponential function with three parameters. These parameters are the design variables in our problem, and optimum solutions for them are determined by Rosenbrock's method. Numerical results are obtained for clamped-free and simply supported columns. It is found that the optimum-designed columns have the shape in which the plastic region appears simultaneously on the whole surface of column along thee length. They have a significantly larger strength than uniform columns having the same weight and length.