A Procedure for Calculating the Plastic Collapse of I-Sections under Bending and Torsion

Mr. E.N. Underwood (Past President), invited by the Chairman to open the discussion, said he had thoroughly enjoyed the authors’ clear description of what was a masterpiece of bridge engineering. He agreed with the Chairman that lessons learned from Brunel and Robert Stephenson could only emphasize what brilliant engineers they had been. Modern experience had proved that their systems could be applied economically today in spite of all the other modern developments.

Equations which express end bending moment and end shearing force for a heavy elastic bar in a generalized state of vibratory motion are obtained, in terms of end transverse displacements and end rotations. These equations may be used to facilitate the solution of problems of vibration in systems of rigidly connected bars. The example of a simple portal frame is considered. H. McCallion and N.F. Rieger

The critical stress for a lipped plate of given geometry is normally found by solving a transcendental equation by numerical methods. By assuming that the minimum value of the buckling coefficient occurs when there is no transmission of shear loading from the lip to the flange, a solution can be obtained by a considerably simplified analysis. This is shown to give close agreement to the exact solution for a particular case. The simplified analysis allows the torsional stiffness of the lip to be taken into account; it can be applied to all lip shapes, and to many forms of constraint on the other longitudinal edge of the plate. P.S. Bulson