Elastic lateral buckling design of semi-rigid frames

A suitable FEM formulation to deal with lateral buckling of semi-continuous elastic frames composed of thin walled members is presented. Any combination of member end connection flexibilities resulting from its minor axis bending and warping restraining actions is incorporated. A nonclassical physical DOF based shape function vector for the member finite element is derived. The effect of shear deformations due to the minor axis bending and nonuniform torsion is accounted for. Other factors, usually associated with the structure lateral buckling resistance, such as concentrated and distributed loads, joint finite sizes, discrete and continuous restraints and prebuckling in-plane displacements are also taken into consideration. Theoretical investigations are illustrated by some numerical examples.