Postbuckling Analysis of Stiffened Laminated Box Columns

Abstract

An analytical‐numerical procedure is developed to investigate the postbuckling behavior of axially compressed, stiffened, laminated box columns. The box column is treated as a stiffened plate structure that may be idealized as an assemblage of laminated, rectangular plate strips and beams. The formulations are based on the classical laminated‐plate theory and the elementary theory of bending and torsion is used for the beam elements. The analysis uses a deflection‐type perturbation technique to determine the buckling load and the postbuckling equilibrium path, ensuring compatibility at the column corners, adding extra in‐plane terms in the strain‐displacement relations, and including shear stresses along the column corners. The effects of initial geometrical imperfections are taken into account. Numerical examples are presented that relate to the performance of perfect and imperfect, unstiffened and stiffened laminated box columns. A comparison is made with existing experimental results.