I Interaction of Plastic Local and Lateral Buckling

Attention is given to the interaction between local and lateral buckling of I‐sections and their influence on plastic flexural ductility in regions of moment gradient. It is shown by means of simple theoretical formulations and the results of a series of tests to failure that rotation capacity in the plastic range is influenced significantly not only by conventional codified parameters, but also by the ratio of span to flange thickness and coincident axial force. In addition, the interaction between local and lateral buckling in the plastic region is demonstrated, and a model is formulated for quantifying this strain‐weakening effect. The results are relevant to the plastic design of structures as well as more general research into methods of improving flexural ductility of I‐sections.