Inelastic Buckling of Columns in the Conventional Testing Machine

The behavior of imperfect columns in conventional testing machine loading is investigated in the case when the buckling stress exceeds the elastic limit of the material. The behavior of the perfect column is then obtained through a limiting process in which the amplitude of the initial deviations from straightness is made to approach zero. It is found that a perfect column cannot bend at or above the tangent modulus load without stress reversal. The maximum load supported by the column is smaller than the reduced modulus load, and it can be smaller than, equal to, or greater than the tangent modulus load. (Author).