Analysis of Biaxially Loaded Steel H-Columns

A number of problems on the inelastic stability of biaxially loaded columns were solved by utilizing an incremental approach. The matrix of influence coefficients, referred to herein as the tangent stiffness matrix, varies with the loading and depends upon the penetration of yielding across the section, the magnitude of external loads, and the displacements of the column. The matrix must therefore be revised with each increment of load, and during each cycle of iteration. Successive corrections are made until the condition of equilibrium between the internal and external forces is satisfied. The analysis covered two different types of loading, proportional and nonproportional. The influences of material yielding, residual stress, end warping restraint, end bending restraint, and initial imperfection were included. The problems of centrally loaded columns and lateral-torsional buckling of beam-columns were also examined by using the biaxial bending theory and the concept of initial imperfection.