Buckling Behavior above the Tangent Modulus Load

The inelastic buckling behavior of a concentrically loaded strut having a reduced rectangular cross section as a mid-section is described in detail. The buckling model is similar to that originally used by F. R. Shanley. 2 In the Shanley model two localized points of area were assumed, whereas in the present model a solid rectangular cross section is introduced which permits a detailed exploration of stress distribution across the section. At various load levels the stress distributions that were described intuitively by Shanley, in his original paper, are determined quantitatively. The behavior of struts held so as to remain straight above the tangent modulus load is also studied, as well as other aspects of behavior that may lead to a better appreciation and understanding of inelastic buckling behavior. The great influence of very slight differences in the shape of the stress strain curve is demonstrated in connection with various aspects of inelastic column behavior.