Abstract
General nonlinear displacement fields for a plate segment comprising the cross section of a prismatic member are derived from Lagrangian strain-displacement relations by abandonning the assumption of no distortion of cross section. Second order displacement fields are also derived from those displacement fields for the buckling analysis. On the basis of the displacement fields and strain components obtained, four simplified differential equations governing the buckled state of I-beams in pure bending are presented, considering the initial curvature due to bending about their major axsis. The solutions obtained using the simplified equations compare favorably with results obtained by a finite strip method with a larger degree of freedoms. The effects of initial curvature of bending are remarkably appeared in the region between local buckling and distortional lateral buckling, and decrease buckling stress of bending in the case of no initial curvature to about 89%.
