No abstract

No abstract

No abstract

Fixed rectangular coordinates Rectangular coordinates through centroid of cross section Displacements in x, y direction Angle of rotation of cross section Displacements at center of a span Displacements in £^ direction Displacement of flange First derivatives with respect to z Modulus of elasticity in tension and compression Modulus of elasticity in shear Minimum and maximum moments of inertia of cross section respectively St. Venant's torsional constant Minimum flexural rigidity Maximum flexural rigidity Torsional rigidity Flexural rigidity of one flange Span length Depth of cross section Cross section property Property of cross section and material Modulus of elasticity, moment of inertia and length of a restraining member Stiffness of restraining member (ft .-lbs./rad. or ft.-lbs./rad./ft.} Torsional stiffness of beam (ft.-lbs./rad. or ft .-lbs./rad./ft.) Continuous torsional restraint stiffness factor (non-dimensional) Point torsional restraint stiffness factor (non-dimensional) Magnitude of a restraining couple Positive interger Length of a beam segment End moment load (ft.-pounds) Concentrated load (pounds) Uniform load (pounds per ft.

The theory of buckling for thin-walled open-profile bars is criticized. Its several derivations are faulted for violating statics, using a variational theorem approximately, using an incorrect variational statement, and/or using an inconsistent filament representation of the bar. Significantly, the theory yields buckling loads that contradict engineering expectations. A theory to replace it with general equations for computing buckling loads is presented. A problem solved under the old and new theories shows how torsional buckling is viewed under the new.